This chapter details Cisco AS5800 routine operations performed on a daily basis to configure router interfaces.
In our discussion, local-based authentication is used. After the Cisco AS5800 hardware is commissioned, PPP is configured and tested as described in the section "Configuring PPP and Authentication".
Verifying Modem Performance
This section describes how to verify and test modem performance on a Cisco AS5800 by using an EXEC terminal shell service.
An EXEC terminal shell service tests modem performance (lower layers) independently of PPP (and higher layers). A terminal-shell service test gets quick test results in a simple environment.
Figure 3-1 shows how traditional DTE-to-DCE relationships map to a Cisco network access server (NAS). Data terminal equipment (DTE) uses data communication equipment (DCE) to send data over the PSTN.
In the context of EIA/TIA-232 and Cisco IOS software:
The DTE is the client PC and the Cisco IOS TTY lines.
The DCE is the client modem and the modem inside the NAS.
The dashed line between the DCEs is the modem carrier running on top of the voiceband circuit through the PSTN. EIA/TIA-232 (whether physical or logical) is used on the DTE lines, not on the DCE link.
The PSTN circuit runs through the circuit-switched half of the NAS.
Figure 3-1 A Standard Dialup Connection
Logical Packet and Circuit Components of a NAS
The NAS functions as a gateway between two different networks:
A circuit-switched network (for example, the PSTN)
A packet-switched network (for example, the Internet)
The NAS is half a circuit switch and half a packet switch (router). EIA/TIA-232 signaling on the line is displayed by the show line command and debug modem command. Figure 3-2 shows the modem access connectivity path.
Figure 3-2 Modem Access Connectivity Path
To understand the general call-processing sequence, match the following numbered list with the numbers shown in Figure 3-2:
1. 64K DS0 circuits extend from the NAS modems, through the internal TDM CSM bus, and through the circuit network (PSTN).
2. The NAS modems demodulate digital streams into analog-voiceband modulation. The virtual EIA/TIA-232 interface connects the modems (DCE) to the TTY lines.
3. The TTY lines are mapped into asynchronous interfaces. Interfaces are Cisco IOS software objects that move packets. TTY lines function at Layer 1. Interfaces function at Layer 2 and Layer 3.
4. The packets are delivered into the IP network.
EIA/TIA-232 in Cisco IOS Software
The Cisco IOS software variation of asynchronous EIA/TIA-232 is shown in Figure 3-3. The variation exists between the Cisco IOS line (DTE) and the NAS modem (DCE).
Six EIA/TIA-232 pins exist between each NAS modem and Cisco IOS line. One or more grounding wires also exist on physical EIA/TIA-232 lines; however, these wires do not convey signaling.
Each pin controls a different EIA/TIA-232 signal.
The arrows in Figure 3-3 indicate the signal transmission direction.
Figure 3-3 Cisco IOS EIA/TIA-232
Tip In Figure 3-3, notice that the DSR signal is the DCD signal for the modem. In the scheme of Cisco IOS software, the DCD pin on the DCE is strapped to the DSR pin on the Cisco IOS DTE side. What the Cisco IOS software calls DSR is not DSR; it is DCD. The DCE's actual DSR pin and ring ignore (RI) pin are ignored by the Cisco IOS software.
Table 3-1 describes how Cisco uses its EIA/TIA-232 pins. The signal direction in the table is from the perspective of the DTE (IOS line):
Data signals (TxD, RxD)
Hardware flow control signals (RTS, CTS)
Modem signals (DTR, DSR, DCD, RI)
Table 3-1 EIA/TIA-232 Signal State Behavior
Signal
Signal Direction
Purpose
Transmit Data (TxD)
——> (Output)
DTE transmits data to DCE.
Receive Data (RxD)
<—— (Input)
DCE transmits received data to DTE.
Request To Send (RTS)
——> (Output)
DTE uses the RTS output signal to indicate if it can receive characters into the Rx input buffer1.
The DCE should not send data to the DTE when DTR input is low (no RTS).
Clear To Send (CTS)
<—— (Input)
DCE signals to DTE that it can continue to accept data into its buffers.
DCE asserts CTS only if the DCE is able to accept data.
Data Terminal Ready (DTR)
——> (Output)
DTE signals to DCE that it can continue to accept data into its buffers.
DTE asserts RTS only if the DTE is able to accept data.
Data Carrier Detect (DCD)
<—— (Input)
DCE indicates to DTE that a call is established with a remote modem. Dropping DCD terminates the session.
DCD will be up on the DCE only if the DCE has achieved data mode with its peer DCE (client modem).
1The name RTS is illogical with the function (able to receive) due to historical reasons.
Cisco IOS Line-Side Inspection
To display the current modem-hardware states applied to a specific Cisco IOS line, enter the show line tty number command. The states of each logical EIA/TIA-232 pin change according to line conditions and modem events.
The following shows a line-side inspection of the idle state for TTY line 1:
5800-NAS#show line tty 1
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
I 1 TTY - inout - - - 2 0 0/0 -
Line 1, Location:"", Type:""
Length:24 lines, Width:80 columns
Status:No Exit Banner
Capabilities:Hardware Flowcontrol In, Hardware Flowcontrol Out
Modem Callout, Modem RI is CD, Line usable as async interface
Allowed transports are pad telnet rlogin v120 lapb-ta. Preferred is telnet.
No output characters are padded
No special data dispatching characters
Table 3-2 describes some of the significant fields shown in the previous example:
Table 3-2 Show TTY Line Field Descriptions
Field
Description
Capabilities
Describes different aspects of the line:
The flowcontrol hardware command displays as "Hardware Flowcontrol In, Hardware Flowcontrol Out."
The modem inout command displays as "modem callout."
The text "Line usable as async interface" means there is an "interface async N" that corresponds to "line N."
The text "Modem RI is CD" displays for historical reasons.
Modem state
Displays the current status of the modem.
Possible values include:
Idle—Modem is ready for incoming and outgoing calls.
Conn—Modem is connected to a remote host.
Busy—Modem is out of service and not available for calls.
D/L—Modem is downloading firmware.
Bad—Modem is in an inoperable state, which is manually configured by the modem bad command.
Bad*—During initial power-up testing, the modem startup-test command automatically put the modem in an inoperable state.
Reset—Modem is in reset mode.
Bad FW—The downloaded modem firmware is not usable.
Modem Hardware state
Displays the EIA/TIA-232 signal state status.
CTS and no DSR are incoming signals. DTR and RTS are outgoing signals. NoDSR means that no call is currently connected.
Understanding Modem Modulation Standards
To optimize modem connect speeds, you must understand the basic modem modulation standards. This section provides the basic rules for achieving maximum V.34 and V.90 modulation speeds:
V.34 modulation should work on any land-line voiceband circuit. V.34 supports speeds ranging from 2400 to 33600 bps.
Speed is a function of:
The amount of usable spectrum across the channel (for example, 2400 to 3429 Hz)
The signal to noise ratio (SNR)
To achieve 33600 bps, the channel must deliver:
A response from 244 to 3674 Hz
A SNR of 38 dB or better
In practice, toll-quality voiceband circuits support V.34 at speeds of 21600 to 33600 bps.
The following six items reduce the achieved V.34 speed:
1. Robbed-bit signaling links in the circuit, which reduce SNR.
2. Extra analog-to-digital conversions. For example, nonintegrated or universal subscriber line concentrators (SLCs) reduce bandwidth and SNR.
3. Load coils on the local loop, which reduce bandwidth.
4. Long local loops, which reduce bandwidth and SNR.
5. The following electrical disturbances in the house wiring, which reduce SNR:
Cross talk from two lines in the same quad cable
Corroded connectors
Bridge-tapped lines running parallel to fluorescent lights
Flat silver-satin cables running parallel to power cables
Extra electrical equipment sharing the same power jack as the modem
6. Voiceband circuits that pass through sub-64k coding, such as a cellular or 32K ADPCM link. With 32k ADMCM, the speed is typically 9600 to 16800 bps.
V.90 Basic Rules
Many circuit components work together to deliver V.90 modulation. See Figure 3-4.
Figure 3-4 V.90 Network Components
Here are the V.90 basic rules:
Select recommended modem code. The following are reliable V.90 releases at the time of this publication:
Run a Cisco IOS release that is compatible with V.90. Table 3-3 shows the V.90 supported Cisco IOS releases at the time of this publication.
Table 3-3 V.90 Supported Cisco IOS Releases
Chassis
Modem Type
Cisco IOS Release
Cisco AS5800
MICA
11.3(6+)AA
12.0(1+)T
Exactly one digital to analog conversion must exist in the circuit. The digital line must connect into a digital switch, not a channel bank. V.90 requires PRI (64k clear-channel DS0s). Channel banks destroy V.90 by adding additional analog-to-digital conversions. Telcos occasionally refer to channel banks as line-side services. Digital switches are sometimes referred to as trunk-side services. Figure 3-5 shows this.
Figure 3-5 No Channel Banks for V.90
In the local loop, less than three miles of twisted-pair copper line with no load coils is ideal. Load coils limit frequencies (passband). V.90 requires a 3000 Hz passband. A circuit that does not deliver a 3200 Hz passband will most likely not deliver V.90. Load coils are common in long loops in North America (at the 3.5 mile mark).
Sometimes the PSTN switch fabric is extended by a digital carrier. It is then converted to analog by a SLC. This setup complies with V.90. The digital-to-analog conversion is moved closer to the subscriber. However, non-integrated or universal SLCs do not comply to V.90.
Use a recommended V.90 client modem.
Electrical house wiring sometimes causes V.90 trainup to fail. For details, see the "V.34 Basic Rules" section.
Initiating a Modem Loopback Test Call
Test the access server's ability to initiate and terminate a modem call. Similar to sending a ping to the next-hop router, this test verifies basic connectivity for modem operations. Successfully performing this test gives you a strong indication that remote clients should be able to dial into the NAS. Figure 3-6 shows this test.
After completing this test, dial into the EXEC from a client PC and a client modem (no PPP).
Figure 3-6 Initiating and Terminating a Modem Call on the Same NAS
Note When calling between two digital modems, you will not achieve V.90. V.90 requires one
digital and one analog modem.
Step 1 From a workstation, open two Telnet sessions into the NAS. One Telnet session is used to simulate the client. The other session is used to administer and run the debugs. In this way, the debug messages will not be scrambled into the loopback screen display.
Step 2 Configure the lines to support dial in, dial out, and outbound Telnet connections:
!
line 1/2/00 1/3/143
modem inout
transport input telnet
!
Step 3 From the administrative Telnet session, turn on the appropriate debug commands. Older software might require the debug modem csmcommand.
5800-NAS#debug isdn q931
ISDN Q931 packets debugging is on
5800-NAS#debug csm modem
Modem Management Call Switching Module debugging is on
5800-NAS#debug modem
Modem control/process activation debugging is on
5800-NAS#show debug
General OS:
Modem control/process activation debugging is on
CSM Modem:
Modem Management Call Switching Module debugging is on
Modem Management Call Switching Module debugging is on
5800-NAS#
Tip For channel associated signaling (CAS), robbed bit signaling (RBS), and R2, use the debug cascommand. If this command is not included in your software, use the modem-mgmt csm debug-rbs command; however, the service internal command is required.
At the time of this publication, the Cisco AS5800 does not support the debug cas command or modem-mgmt csm debug-rbs command. As a workaround, complete the following steps:
a. Determine the slot positions of each card. Enter the show dial-shelf command.
b. Access the trunk card's console port. Enter the dsip console slaveX command where X is the slot of the card that you want to perform debugging on.
c. Enter the command debug trunk cas portport-numbertimeslotsrange.
Step 4 Ensure that your EXEC session receives logging and debug output from the NAS:
5800-NAS#logging console
Step 5 From the client Telnet session, Telnet into one of the idle modems (not in use). To do this, Telnet to an IP address on the NAS (Ethernet or Loopback) followed by 2000 plus a TTY line number. This example Telnets to TTY line 1 (2001).
5800-NAS#telnet 172.22.66.23 2001
Trying 172.22.66.23, 2001 ... Open
Note This step is also known as a reverse
Telnet.
For a Cisco AS5800, create an arbitrary IP host followed by a reverse Telnet. Use the show modemshelf/slot/port command to determine which modem is associated with which TTY line. The following example Telnets to TTY 500, which maps to modem 1/2/68.
Step 6 Log in from the client Telnet session. The Cisco IOS software sends out a username-password prompt.
This is a secured device.
Unauthorized use is prohibited by law.
User Access Verification
Username:admin
Password:
Sep 23 05:04:58.047: TTY0: pause timer type 1 (OK)
Sep 23 05:04:58.051: TTY1: asserting DTR
Sep 23 05:04:58.051: TTY1: set timer type 10, 30 seconds
Sep 23 05:05:03.583: TTY1: set timer type 10, 30 seconds
Step 7 Enter the at command to test connectivity to the NAS modem. The modem reports an "OK" return message.
at
OK
Step 8 Dial the PRI phone number assigned to the NAS (in this example, 5551234). A connect string appears when the modem connects.
atdt5551234
CONNECT 33600 /V.42/V.42bis
In this example:
Modulation connect speed = 33600 bps. Expect to get a maximum of 33600 bps if you use a PRI line. If you use RBS, expect to get a maximum of 31200 bps.
Error correction = V.42
Data compression = V.42bis
Step 9 From the administrative Telnet session, inspect the debug output:
000456: *May 2 23:02:05.462 UTC: TTY1/2/12: set timer type 10, 30 seconds
Note You must have the logging console feature turned on to view this output on the screen.
The bearer capability 0x8090A2 indicates an analog voice call. Alternative bearer services include 64K data calls, which are indicated by 0x8890. The calling party number is 408 (also known as ANI). The called party number is 5551234 (also known as DNIS). The debug q931 command shows the call coming into the NAS over ISDN.
*Jan 1 00:34:47.867:VDEV_ALLOCATE:1/2 is allocated from pool System-def-Mpool
MICA modem 1/2 goes offhook and receives the call. The debug modem csm command shows the call getting switched over to a modem.
*Jan 1 00:34:49.159:Mica Modem(1/2):State Transition to Connect
*Jan 1 00:34:53.903:Mica Modem(1/2):State Transition to Link
*Jan 1 00:35:02.851:Mica Modem(1/2):State Transition to Trainup
*Jan 1 00:35:04.531:Mica Modem(1/2):State Transition to EC Negotiating
*Jan 1 00:35:04.711:Mica Modem(1/2):State Transition to Steady State
*Jan 1 00:35:04.755:TTY3:DSR came up
*Jan 1 00:35:04.755:tty3:Modem:IDLE->(unknown)
Inspect the different modem trainup phases. The modem goes from Connect to Steady State in 15 seconds. The debug modem csm command displays the trainup phases. The debug modem command displays the logical EIA/TIA-232 transition message "DSR came up."
*Jan 1 00:35:04.759:TTY3:EXEC creation
*Jan 1 00:35:04.759:TTY3:set timer type 10, 30 seconds
*Jan 1 00:35:08.915:TTY3:Autoselect(2) sample 61 <------------------- a
*Jan 1 00:35:09.187:TTY3:Autoselect(2) sample 6164 <----------------- d
*Jan 1 00:35:09.459:TTY3:Autoselect(2) sample 61646D <--------------- m
*Jan 1 00:35:09.459:TTY3:Autoselect(2) sample 61646D69 <------------- i
*Jan 1 00:35:09.715:TTY3:Autoselect(2) sample 646D696E <------------- n
Decode the incoming character-byte stream for an EXEC shell login (no PPP). In this example, match the username "admin" to the character stream: 616D696E0D = admin carriage return.
The Cisco IOS samples four packets at a time. It searches for a header that matches one of your autoselect styles. The debug modem command generates the autoselect debug output.
*Jan 1 00:35:09.715:TTY3:set timer type 10, 30 seconds
*Jan 1 00:35:11.331:TTY3:Autoselect(2) sample [suppressed--line is not echoing]
*Jan 1 00:35:11.667:TTY3:Autoselect(2) sample [suppressed--line is not echoing]
*Jan 1 00:35:11.987:TTY3:Autoselect(2) sample [suppressed--line is not echoing]
*Jan 1 00:35:11.987:TTY3:Autoselect(2) sample [suppressed--line is not echoing]
*Jan 1 00:35:11.987:TTY3:Autoselect(2) sample [suppressed--line is not echoing]
*Jan 1 00:35:12.339:TTY3:Autoselect(2) sample [suppressed--line is not echoing]
*Jan 1 00:35:12.391:TTY3:create timer type 1, 600 seconds
5800-NAS>
Type 10 is the login timer. The timeout is 30 seconds. The user's EXEC-shell login password is suppressed.
Step 10 Identify who is logged in. TTY line 3 corresponds to modem 1/2. Use the show terminal command to see which modem is assigned to the TTY line.
5800-NAS> show user
Line User Host(s) Idle Location
3 tty 3 admin idle 0
* 98 vty 0 joe 172.22.66.1 0 leftfield.corporate.com
Interface User Mode Idle Peer Address
d. Program the terminal window not to pause in the middle of a screen display. To adjust the display output on a Cisco AS5800, enter the terminal length 0 command instead.
5800-NAS> terminal length 0
Step 11 Generate traffic across the modem link. Force the answering modem (in the NAS) to send a data stream to the client modem. The data stream generated by the show modem log command is about 1 MB. The data should scroll freely for one or two minutes.
5800-NAS> show modem log
doc-rtr58-01#sh modem log
Modem 1/2/00 Events Log:
3w2d :Startup event:MICA Hex modem (Managed)
Modem firmware = 0.7.3.7
2w2d :Modem State event:
State:Terminate
2w2d :Modem State event:
State:Idle
Modem 1/2/01 Events Log:
3w2d :Startup event:MICA Hex modem (Managed)
Modem firmware = 0.7.3.7
2w2d :Modem State event:
State:Terminate
2w2d :Modem State event:
State:Idle
Modem 1/2/02 Events Log:
3w2d :Startup event:MICA Hex modem (Managed)
Modem firmware = 0.7.3.7
2w2d :Modem State event:
State:Terminate
2w2d :Modem State event:
State:Idle
Step 12 Look at the modem's operational statistics and verify that you have acceptable speed, line shape, and throughput. In this example, modem 1/2 accepts the call.
If you do not have a scroll bar in your Telnet application, limit terminal length to 24 lines to see all the command output.
If you are using Microcom modems, enter the modem at-modeslot/port command followed by the at@e1 command.
5800-NAS> show modem operational-status 1/2/00
Modem(1/2/00) Operational-Status:
Parameter #0 Disconnect Reason Info: (0x0)
Type (=0 ): <unknown>
Class (=0 ): Other
Reason (=0 ): no disconnect has yet occurred
Parameter #1 Connect Protocol: LAP-M
Parameter #2 Compression: V.42bis both
Parameter #3 EC Retransmission Count: 0
Parameter #4 Self Test Error Count: 0
Parameter #5 Call Timer: 597 secs
Parameter #6 Total Retrains: 0
Parameter #7 Sq Value: 4
Parameter #8 Connected Standard: V.34+
Parameter #9 TX,RX Bit Rate: 33600, 33600
Parameter #11 TX,RX Symbol Rate: 3429, 3429
Parameter #13 TX,RX Carrier Frequency: 1959, 1959
Parameter #15 TX,RX Trellis Coding: 16, 16
Parameter #16 TX,RX Preemphasis Index: 0, 0
Parameter #17 TX,RX Constellation Shaping: Off, Off
Table 3-4 Operational Parameter Descriptions for a Loopback Test Call
Parameter
Description
Parameter #1 Connect Protocol: LAP-M
LAP-M is the connection protocol.
Parameter #6 Total Retrains: 0
The modem has no retrain counts.
Parameter #8 Connected Standard: V.34+
The modem connects at V.34.
Parameter #9 TX,RX Bit Rate: 33600, 33600
The receive and transmit bit rate is 33600 bps, which is the fastest possible V.34 speed. You will never attain V.90 with this test. MICA-to-MICA calls default to V.34 modulation. V.90 requires one analog modem.
Parameter #11 TX,RX Symbol Rate: 3429, 3429
The transmit and receive symbol rate is 3429. To achieve 33600 bps, you must have a 3429 Hz passband.
Parameter #21 Signal Noise Ratio: 41 dB
The signal to noise ratio is 41 dB.
Parameter #26 Far End Echo Level: -52 dBm
Use this field to detect a near-end digital-to-analog conversion. For this test, an acceptable value is less than -55 dB.
If you see a high level of far end echo (-55 or higher), a digital-to-analog conversion probably exists between the NAS and the switch. This conversion severely impairs modem performance.
The number of characters transmitted and received by the modem.
Line shape:
..............................*
................................*
.................................*
................................*
................................*
.................................*
.................................*
.................................*
................................*
.................................*
A line shape is the frequency-response graph of the channel.
For this modem loopback test call, there should be no rolloff (even at the highest frequency). High-end rolloff is characteristic of an analog-to-digital conversion (not good).
A flat vertical line shape is an ideal V.90 line shape. ISDN uses a 64KB clear channel. No statistical roll off should exist at the low end or the high end of the spectrum. The spectrum has a Y and X axis.
The Y axis (vertical) represents frequencies from 150 Hz (top of chart) to 3750 Hz (bottom of chart) in 150 Hz steps. A flat spectrum plot is best, it is available for V.34, V.90, and K56Flex.
The X axis (horizontal) represents a normal amplitude. The graph identifies nulls, bandwidth, and distortion (irregular shape).
Step 13 Turn off all debug commands:
5800-NAS# undebug all
All possible debugging has been turned off
Initiating and Inspecting a V.90 Test Call
Before you let users dial in to the NAS, initiate and inspect a V.90 test call. V.90 call performance is heavily dependent upon the telco's network topology. There are many variables.
Most modem manufactures have unique AT command sets. The AT commands used in the following procedure may not be supported by your modem. For more information, refer to the following:
Step 1 Locate a client PC, client modem, and an analog line.
Step 2 Test your EIA/TIA-232 connection to the client modem:
at
OK
Step 3 Verify that the modem is running the recommended firmware version. The following example shows a U.S. Robotics 56K fax external modem running V.4.11.2. Compare the firmware version with the version that is posted on the modem vendor's website.
The ati3 and ati7 modem firmware commands are commonly used and are shown below:
ati3
U.S. Robotics 56K FAX EXT V4.11.2
OK
ati7
Configuration Profile...
Product type US/Canada External
Product ID: 00568602
Options V32bis,V.34+,x2,V.90
Fax Options Class 1/Class 2.0
Line Options Caller ID, Distinctive Ring
Clock Freq 92.0Mhz
EPROM 256k
RAM 32k
FLASH date 6/3/98
FLASH rev 4.11.2
DSP date 6/3/98
DSP rev 4.11.2
OK
Step 4 Verify that the modem is configured correctly. Enter the ati4 (USR) or at&v (Conexant) command. To reset the modem to the factory defaults, enter the at&f, at&f1, or at&f2 command.
Step 5 Dial the access server's telephone number, log in, and access the EXEC shell. The client modem is connected at 48000 bps in this example.
atdt14085551234
CONNECT 48000/ARQ
This is a secured device.
Unauthorized use is prohibited by law.
User Access Verification
Username:user
Password:
5800-NAS>
Step 6 Inspect your call on the access server. In the example, the call landed on TTY line 1. The call has been up for 36 seconds.
5800-NAS> show caller
Active Idle
Line User Service Time Time
vty 0 - VTY 00:07:46 00:00:00
5800-NAS> show caller
Note The show caller command is supported in Cisco IOS
Release 11.3 AA and 12.0 T. Use the show user
command if your software does not support the show caller command.
Step 7 Inspect the physical terminal line that received the call. In the example, the call landed on modem 1/0.
5800-NAS> show terminal
Line 1/2/10, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Status: PSI Enabled, Ready, Active, No Exit Banner
Capabilities: Hardware Flowcontrol In, Hardware Flowcontrol Out
Allowed transports are lat pad v120 telnet rlogin dsipcon. Preferred is lat.
No output characters are padded
No special data dispatching characters
Step 8 Program the display window so it does not pause in the middle of a screen display:
5800-NAS> terminal length 0
Step 9 Generate traffic across the modem link. Perform a lightweight stress test between the modems to generate meaningful modem-performance statistics.
5800-NAS> show modem log
Modem 1/2/00 Events Log:
3w4d :Startup event:MICA Hex modem (Managed)
Modem firmware = 2.7.1.0
3w4d :RS232 event: noRTS, noDTR, CTS, noDCD
3w4d :RS232 event: noRTS, DTR, CTS, noDCD
The output generated by the show modem log command sends a large data stream across the modem link - about 1 MB of data. The data should scroll freely for one or two minutes.
Step 10 Inspect the NAS modem that answered the call, and verify that it has acceptable connect speed, throughput, and line shape. This example examines MICA modem 1/0. If you have Microcom modems, enter the modem at-modeslot/port command followed by the at@e1 command.
5800-NAS> show modem operational-status 1/2/00
Modem(1/2/00) Operational-Status:
Parameter #0 Disconnect Reason Info: (0x0)
Type (=0 ): <unknown>
Class (=0 ): Other
Reason (=0 ): no disconnect has yet occurred
Parameter #1 Connect Protocol: LAP-M
Parameter #2 Compression: None
Parameter #3 EC Retransmission Count: 2
Parameter #4 Self Test Error Count: 0
Parameter #5 Call Timer: 118 secs
Parameter #6 Total Retrains: 0
Parameter #7 Sq Value: 3
Parameter #8 Connected Standard: V.90
Parameter #9 TX,RX Bit Rate: 48000, 28800
Parameter #11 TX,RX Symbol Rate: 8000, 3200
Parameter #13 TX,RX Carrier Frequency: 0, 1920
Parameter #15 TX,RX Trellis Coding: 0, 16
Parameter #16 TX,RX Preemphasis Index: 0, 6
Parameter #17 TX,RX Constellation Shaping: Off, Off
Parameter #39 Robbed Bit Signalling (RBS) pattern: 0
Parameter #40 Digital Pad: 6.0 dB, Digital Pad Compensation:None
Line Shape:
.........................*
................................*
.................................*
.................................*
................................*
.................................*
.................................*
.................................*
................................*
................................*
................................*
................................*
................................*
................................*
................................*
................................*
................................*
Table 3-5 describes the significant output fields (bold font) in the previous example:
Table 3-5 Show Modem Operational-Status Field Descriptions
Parameter
Description
Parameter #6 Total Retrains: 0
Total retrains and speed shifts for the current connection. There are no retrains.
Parameter #8 Connected Standard: V.90
V.90 modulation is negotiated.
Standard connect protocol which can be V.21, Bell03, V.22, V.22bis, Bell212, V.23, V.32, V.32bis, V.32terbo, V.34, V.34+, K56Flex, or V.90.
Parameter #9 TX, RX Bit Rate: 48000, 28800
The transmit speed (TX) is 48000 bps. The receive speed (RX) is 28800 bps.
TX is the bit rate from the local DCE (NAS modem) to the remote DCE (client modem). RX is the bit rate from the remote DCE to the local DCE. V.90 uplink speed tends to be lower than V.34 uplink speed.
Parameter #21 Signal Noise Ratio: 36 dB
The signal to noise ratio (SNR) is 36 dB. (40 dB is a perfect SNR.
MICA measures the SNR in the signal band. The SNR value ranges from 0 to 70 dB, and it changes in 1 dB steps.
A 28.8 kbps connection requires a SNR of about 37 dB. SNRs lower than 37 dB reduce the quality of the connection.
A 33.6 kbps connection requires a SNR of about 38 to 39 dB.
67109 characters are transmitted by the NAS modem to the client modem over the synchronous/asynchronous connection.
Line shape:
.........................*
................................*
.................................*
.................................*
................................*
.................................*
.................................*
.................................*
................................*
................................*
................................*
................................*
................................*
................................*
................................*
A line shape is the frequency-response graph of the channel.
A flat vertical line shape is an ideal V.90 line shape. ISDN uses a 64-kb clear channel. No statistical roll off should exist at the low end or the high end of the spectrum. The spectrum has a Y and X axis.
The Y axis (vertical) represents frequencies from 150 Hz (top of chart) to 3750 Hz (bottom of chart) in 150 Hz steps. A flat spectrum plot is best, it is available for V.34, V.90, and K56Flex.
The X axis (horizontal) represents a normal amplitude. The graph identifies nulls, bandwidth, and distortion (irregular shape).
Step 11 Enter the +++ command to jump back to the client modem and examine client-side performance statistics. The modem connection to the NAS is not dropped.
5800-NAS>+++
OK
at
OK
In the example, the client modem reports both "OK" messages. The +++modem-escape sequence is similar to a router's Telnet-escape mode (Shift + Ctrl + 6 + x). See Figure 3-7.
Figure 3-7 Using Modem-Escape Mode to View Client-Side Modem Statistics
Step 12 Enter the ati6 command to display, among other things, the receive and transmit-carrier speeds. Compare the displayed information with the output from the show modem operational-status command.
If ati6 is not supported by your modem, try at&v1. For additional client report statistics, enable Windows modemlog.txt or ppplog.txt files.
Step 13 Inspect frequency levels (dB) and other diagnostic functions. The following AT commands display the client modem's view of the frequency response. The display is a companion to the output of the show modem operational-status command (see Step 9).
aty11
Freq Level (dB)
150 24
300 23
450 22
600 22
750 22
900 22
1050 22
1200 22
1350 22
1500 22
1650 22
1800 23
1950 23
2100 23
2250 23
2400 23
2550 23
2700 23
2850 23
3000 23
3150 23
3300 24
3450 25
3600 27
3750 31
ati11
U.S. Robotics 56K FAX EXT Link Diagnostics...
Modulation V.90
Carrier Freq (Hz) None/1920
Symbol Rate 8000/3200
Trellis Code None/64S-4D
Nonlinear Encoding None/ON
Precoding None/ON
Shaping ON/ON
Preemphasis (-dB) 6/2
Recv/Xmit Level (-dBm) 19/10
Near Echo Loss (dB) 7
Far Echo Loss (dB) 0
Carrier Offset (Hz) NONE
Round Trip Delay (msec) 24
Timing Offset (ppm) 1638
SNR (dB) 48.1
Speed Shifts Up/Down 0/0
Status : uu,5,13Y,19.4,-15,1N,0,51.1,7.3
OK
Step 14 (Optional) To return to online mode and the router prompt, enter the ato command. After your enter this command, however, the +++ escape sequence is still in the EXEC session's input buffer. If you press the carriage return (<CR>), you will receive an error about +++ being an unknown command. To clear the input buffer, type Ctrl U after the ato command.
ato
% Unknown command or computer name, or unable to find computer address
5800-NAS>
Configuring PPP and Authentication
This section describes how to configure the Cisco AS5800 for PPP and local authentication.
After local authentication is verified, use TACACS+ and a remote authentication server or RADIUS.
Configuring PPP Authentication for Local AAA
Configure AAA to perform log in authentication by using the local username database. The login keyword authenticates EXEC terminal shell users. Additionally, configure PPP authentication to use the local database if the session was not already authenticated by login.
Step 1 Create a local log in username database in global configuration mode. In this example, admin is used for the administrator and the remote client's login password is user.
!
username admin password adminpass
username theuser password theuserpass
!
Warning This step also prevents you from getting locked out of the NAS. If you get locked out, you must reboot the device and perform password recovery.
Step 2 Configure local AAA security in global configuration mode. You must enter the aaa new-model command before the other two authentication commands.
!
aaa new-model
aaa authentication login default local
aaa authentication ppp default if-needed local
!
Step 3 Log in with your username and password:
5800-NAS# login
This is a secured device.
Unauthorized use is prohibited by law.
User Access Verification
Username: theuser
Password:
5800-NAS#
Caution A successful login means that your local username will work on any TTY or VTY line. Do not disconnect your session until you can log in. (If you get locked out, you will need to perform password recovery by rebooting the device.)
Configuring IPCP Options
Create a pool of IP addresses to assign to the PC clients dialing in. As the clients connect, they request IP addresses from the NAS.
Tip Remote ISDN LANs and remote nodes are primarily differentiated by an IP addressing scheme. Remote LANs can appear as remote nodes by using port address translation (PAT).
Step 1 Define the local IP address pool and DNS servers:
!
ip local pool addr-pool 172.22.90.2 172.22.90.254
!
async-bootp dns-server 172.30.10.1 172.30.10.2
!
For clients using server-assigned addressing (if there are any) you must specify primary and secondary DNS servers. The clients send config-requests to the NAS if the clients are configured to receive NAS assigned WINS and DNS servers.
Note RFC 1877 describes DNS and NBNS servers. The
domain name must also be configured on the client.
Step 2 Verify that the IP address pool was created:
5800-NAS# show ip local pool
Pool Begin End Free In use
addr-pool 172.22.90.2 172.22.90.254 253 0
5800-NAS#
Configuring LCP Options
The group-async interface is a template that controls the configuration of all the asynchronous interfaces in the NAS.
Asynchronous interfaces:
Are lines that can run in PPP mode
Use the same number as its corresponding line
Save you time and configuration file size by configuring the asynchronous interfaces as a group-async
The client PPP framing must match the Cisco IOS interface. Figure 3-8 shows this concept.
Figure 3-8 Modem Dialup PPP Framing
The following group-async configuration applies to asynchronous interfaces 1/2/00 through 1/10/143:
!
interface Group-Async0
ip unnumbered FastEthernet0/1/0
encapsulation ppp
async mode interactive
ppp authentication chap pap
peer default ip address pool addr-pool
no cdp enable
no ip directed-broadcast
group-range 1/2/00 1/10/143
!
Table 3-6 describes the previous configuration snippet in more detail:
Table 3-6 Interface Group Async Command Descriptions
Command
Purpose
ip unnumbered FastEthernet0/1/0
Conserves IP address space by configuring the asynchronous interfaces as unnumbered.
encapsulation ppp
Enables PPP.
async mode interactive
Configures interactive mode on the asynchronous interfaces. Interactive means that users can dial in and get to a shell or PPP session on that line.
ppp authentication chap pap
Enables CHAP and PAP authentication on the interface during LCP negotiation. The NAS first requests to authenticate with CHAP. If CHAP is rejected by the remote client (modem), then PAP authentication is requested.
peer default ip address pool addr-pool
Assigns dial-in client IP addresses from the pool named addr-pool.
no cdp enable
Disables the Cisco discovery protocol.
no ip directed-broadcast
Prevents IP directed broadcasts.
group-range 1/2/00 1/10/143
Specifies the range of asynchronous interfaces to include in the group, which is usually equal to the number of modems you have in the NAS.
(The session may pause for several seconds when you issue this command.)
Enabling PPP Autoselect
Enable remote PPP users to dial in, bypass the EXEC facility, and automatically start PPP on the line.
!
line 1/2/00 1/10/143
autoselect during-login
autoselect ppp
!
These two autoselect commands:
Provide the transparent launching of shell and PPP services on the same lines.
Circumvent the need to alert the NAS by pressing the return key. Older versions of Cisco IOS software did not have this feature and required the peer to hit return before the username was displayed.
Note The autoselect during-login command displays the
username:password prompt after modems connect.
Testing Asynchronous PPP Connections
Before you troubleshoot PPP negotiation or AAA authentication, you need to understand what a successful PPP and AAA debug sequence looks like. In this way, you can save time and effort when comparing a successful debug session against a faulty completed debug sequence.
Successful PPP Negotiation Debug
The following steps describe how to initiate a PPP test call and interpret a successful debug sequence.
Step 1 Enter the appropriate debug commands:
5800-NAS# debug ppp authentication
PPP authentication debugging is on
5800-NAS# debug aaa authentication
AAA Authentication debugging is on
5800-NAS# show debug
General OS:
AAA Authentication debugging is on
PPP:
PPP authentication debugging is on
Step 2 Make sure that your EXEC session receives logging and debug output:
5800-NAS# logging console
Step 3 From the client, send a test call into the NAS by using dialup networking. Figure 3-9 shows an example Windows dialup networking display.
Figure 3-9 Windows Dialup Networking
Step 4 Go to the NAS terminal screen to observe and interpret the debug output messages. As the call enters the NAS, debug output is created.
When examining PPP between two remote peers:
a. First check to see if DSR came up.
b. Verify that both sides get through LCP negotiation. If they do, check authentication.
c. After authentication succeeds, check IPCP negotiation.
d. If no debug output appears, troubleshoot ISDN Q.931. Use the debug isdn q931 command.
Given the debug commands entered in Step 1, the following debug output should be generated by the call:
In this example, the call enters the NAS on channel 1/0/0:4:21. This channel maps to the 21st DS0 channel of the 4th PRI line of a CT3 card. Eventually the call terminates on modem 441.
*Sep 24 13:05:55.404: AAA/AUTHEN (693233173): status = PASS
*Sep 24 13:05:55.404: As1/2/09 PAP: O AUTH-ACK id 1 len 5
The example above shows that local authentication was successful.
Failed PPP Negotiation Debugging and Troubleshooting
Failed authentication is a common occurrence. Misconfigured or mismatched user names and passwords create error messages in debug output.
The following example shows that the username maddog does not have permission to dial into the NAS. The NAS does not have a local username configured for this user. To fix the problem, use the usernamenamepassword password command to add the username to the local AAA database in the NAS:
Figure 3-10 provides a flowchart for troubleshooting the following three PPP layers:
Physical layer
Link Control Protocol (LCP) and authentication layer
Network Control Protocol (NCP) layer
Figure 3-10 Troubleshooting Flow Chart for PPP and Authentication
LCP negotiation is a series of LCP packets exchanged between PPP peers to negotiate a set of options and option values when sending data. The LCP negotiation is actually two separate dialogs between two PPP peers (Peer1 and Peer 2):
Peer 1 and Peer 2 do not have to use the same set of LCP options. When a PPP peer sends its initial Configure-Request, the response is any of the following:
A Configure-Nack because one or more options have unacceptable values.
A Configure-Reject because one or more of the options are unknown or not negotiable.
A Configure-Ack because all of the options have acceptable values.
When a PPP peer receives a Configure-Nack or Configure-Reject in response to its Configure-Request, it sends a new Configure-Request with modified options or option values. When a Configure-Ack is received, the PPP peer is ready to send data.
Figure 3-11 shows an example LCP negotiation process for Peer 1 using the fictional options W, X, Y, Z. Additionally, Figure 3-11 shows Peer 1 sending data to Peer 2 only. Separate LCP negotiation must be configured so that Peer 2 can send data back to Peer 1. Very often, the LCP packets for both Peer 1 and Peer 2 are intermixed during the connection process (that is, Peer 1 is configuring the way it sends data at the same time as Peer 2.).
Peer 1 sends a Configure-Request requesting option W, option X set to 100, option Y set to 0, and option Z. (Options W and Z are flag options.)
Peer 2 does not understand option Z so it sends a Configure-Reject containing option Z.
Peer 1 sends a new Configure-Request packet requesting option W, option X set to 100, and option Y set to 0.
Peer 2 prefers that option X be set to 200 so it sends a Configure-Nack containing option X and its preferred value.
Peer 1 sends a new Configure-Request packet requesting option W, option X set to 200, and option Y set to 0.
Peer 2 sends a Configure-Ack.
Each time Peer 1 sends a new Configure-Request, it changes the Identifier value in the LCP header so that Configure-Requests can be matched with their responses.
Inspecting Active Call States
After a basic PPP modem call comes into the NAS, you should use some show commands to inspect several active call statistics. If you try to use the client's web browser after the modems connect, you will test DNS, IP, and other functions. If your test fails, try pinging the DNS server from the device that dialed in.
Show Caller Statistics
The show caller command is used to:
View individual users and consumed resources on the NAS.
Inspect active call statistics for large pools of connections. (Debug commands produce too much output and tax the CPU too heavily.)
Display the absolute and idle times for each user. The current values for both of these settings are displayed on the TTY line and the asynchronous interface. Users that have been idle for unacceptably long periods of time can be easily identified. By using this information, you can define timeout policies and multiple grades of services for different users.
The show caller command has many options:
5800-NAS# show caller ?
full Provide expanded caller information
interface Provide information on one interface
ip Display IP information
line Provide information on one line
timeouts Display session and idle limits and disconnect time
user Display information for a particular user
| Output modifiers
<cr>
5800-NAS# show caller
Active Idle
Line User Service Time Time
vty 0 admin VTY 00:54:39 00:00:00
tty 441 theuser Async 00:00:15 00:00:00
As1/2/09 theuser PPP 00:00:08 00:00:00
5800-NAS# show caller user theuser
User: theuser, line tty 441, service Async
Active time 00:01:24, Idle time 00:01:05
Timeouts: Absolute Idle Idle
Session Exec
Limits: - - 00:10:00
Disconnect in: - - -
TTY: Line 1/2/09, running PPP on As1/2/09
Location: PPP: 192.168.10.4
DS0: (slot/unit/channel)=0/4/21
Status: Ready, Active, No Exit Banner, Async Interface Active
HW PPP Support Active, Modem Detected
Capabilities: Hardware Flowcontrol In, Hardware Flowcontrol Out
Modem Callout, Modem RI is CD,
Line usable as async interface, Modem Autoconfigure
Modem State: Ready, Modem Configured
User: theuser, line As1/2/09, service PPP
Active time 00:01:17, Idle time 00:01:05
Timeouts: Absolute Idle
Limits: - -
Disconnect in: - -
PPP: LCP Open, PAP (<- AAA), IPCP
IP: Local 172.22.66.23, remote 172.22.90.2
Counts: 30 packets input, 1640 bytes, 0 no buffer
1 input errors, 1 CRC, 0 frame, 0 overrun
14 packets output, 290 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
In the previous example, notice that one call uses the following system resources:
TTY line 441
Asynchronous interface 1/2/09 (shelf/slot/port)
DS0 channel number 0/4/21
Modem 1/2/09
Note Different data is presented at each layer of the connection. Understanding the roles of the
layers is very useful for troubleshooting purposes. The show
caller user "username" detailed command displays detailed LCP negotiated parameters.
Table 3-7 describes some of the significant display output fields of the show caller user command:
Table 3-7 Show Caller User Command Descriptions
Field
Description
User: theuser, line tty 441, service Async
Active user on line TTY 441. The output fields are very similar to the show line command.
DS0: (slot/unit/channel)=0/4/21
The DS0 channel used by the call.
User: admin, line As1/2/09, service PPP
Active user on asynchronous interface 1/2/09. The timeouts working on the PPP layer are displayed, which are different from the TTY line timeouts.
PPP: LCP Open, CHAP (<- AAA), IPCP
Superficial information about what is open in PPP. The field "(<- AAA)" is somewhat misleading. Local authentication is also from AAA.
For more detailed IPCP information, enter the show caller user detail command.
IP: Local 172.22.66.23, remote 172.22.90.2
The IP addresses on each end of the link. These values are only displayed on the output for the asynchronous interface.
Counts:
Counters from the show interface async 1/2/09 command output.
Fast Switching and Route Caching Statistics
Inspect fast-switching and route-caching performance statistics for the call. Incoming asynchronous calls can be fast switched. However, some features disable fast switching.
Step 1 Inspect the queuing characteristics of the asynchronous interface. Notice that the queuing strategy is first-in-first-out (fifo).
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
Step 2 Inspect the IP settings of the interface. Notice that IP fast switching is disabled, because TCP/IP header compression is enabled. Turn off TCP/IP header compress to enable fast switching. Enter the no ip tcp header-compression command on the asynchronous interface.
5800-NAS# show ip int async 1/2/02
Async1/2/02 is up, line protocol is up
Interface is unnumbered. Using address of FastEthernet0/1/0 (172.22.66.23)
Broadcast address is 255.255.255.255
Peer address is 172.22.90.2
MTU is 1500 bytes
Helper address is not set
Directed broadcast forwarding is enabled
Outgoing access list is not set
Inbound access list is not set
Proxy ARP is enabled
Security level is default
Split horizon is enabled
ICMP redirects are always sent
ICMP unreachables are always sent
ICMP mask replies are never sent
IP fast switching is disabled
IP fast switching on the same interface is disabled
IP multicast fast switching is enabled
Router Discovery is disabled
IP output packet accounting is disabled
IP access violation accounting is disabled
TCP/IP header compression is enabled and compressing
RTP/IP header compression is disabled
Probe proxy name replies are disabled
Gateway Discovery is disabled
Policy routing is disabled
Network address translation is disabled
Step 3 Look at the fast-switching cache in action. Notice that only packets destined to the Fast Ethernet interface are currently cached.
5800-NAS# show ip cache
IP routing cache 3 entries, 560 bytes
109 adds, 106 invalidates, 3 refcounts
Minimum invalidation interval 2 seconds, maximum interval 5 seconds,
quiet interval 3 seconds, threshold 0 requests
Invalidation rate 0 in last second, 0 in last 3 seconds
Last full cache invalidation occurred 22:17:01 ago
Table 3-8 provides a list of terms for this section.
Table 3-8 List of Terms
Term
Description
DSP
Digital Signal Processor (DSP). The processor that does the modulating and demodulating. The modem modulation protocols, such as V.34 and V.90, that run in the DSP.
Firmware1
Name for Microcom modem code.
MICA module
MICA modem card containing 6 (HMM) or 12 (DMM) modems.
Portware
Name for MICA modem code.
SPE
Service Processing Element (SPE). A SPE unit is defined as the smallest software downloadable unit.
For Microcom, an SPE is an individual modem. For MICA, SPE is either 6 or 12 modems, depending on whether the MICA module is single or double density.
ucode
Short for microcode. Microcode in a Cisco NAS is code that gets loaded into a card, and it is typically bundled with the Cisco IOS software image. (In general, Cisco does not refer to modem code microcode.)
1Examples and text that refer to both MICA and Microcom modems use the term firmware (not portware).
The following documents are related to modem management operations:
Inspecting and upgrading modem firmware is a fundamental part of commissioning a NAS. Cisco posts new firmware versions on CCO for you to download via FTP. For more information, go to the Cisco Software Center at the following URL: http://www.cisco.com/kobayashi/sw-center/sw-access.shtml
A specific architecture surrounds integrated modem technology. Integrated modems get their modem firmware from a file that is stored in one of three places:
Bundled into the Cisco IOS software
Stored in Flash memory
Stored in bootFlash memory
The modem looks first for its firmware inside the bundled Cisco IOS software image. The modem does not look outside the bundled image unless you manually change the configuration settings by using the copy source modem command or spe command.
Inspecting Modem Firmware
Before you upgrade modem firmware for MICA or Microcom modems, you should perform the following tasks:
Step 1 Determine the version of firmware that is currently loaded in each modem (for example, 2.6.2.0).
5800-NAS# show modem version
Modem Range Module Firmware Rev Upgrade
1/2/00 1/2/11 0 2.6.2.0 -
1/2/12 1/2/23 1 2.6.2.0 -
1/2/24 1/2/35 2 2.6.2.0 -
1/2/36 1/2/47 3 2.6.2.0 -
1/2/48 1/2/59 4 2.6.2.0 -
1/2/60 1/2/71 5 2.6.2.0 -
1/2/72 1/2/83 6 2.6.2.0 -
1/2/84 1/2/95 7 2.6.2.0 -
1/2/96 1/2/107 8 2.6.2.0 -
1/2/108 1/2/119 9 2.6.2.0 -
1/2/120 1/2/131 10 2.6.2.0 -
1/2/132 1/2/143 11 2.6.2.0 -
1/3/00 1/3/11 0 2.6.2.0 -
1/3/12 1/3/23 1 2.6.2.0 -
1/3/24 1/3/35 2 2.6.2.0 -
1/3/36 1/3/47 3 2.6.2.0 -
1/3/48 1/3/59 4 2.6.2.0 -
1/3/60 1/3/71 5 2.6.2.0 -
1/3/72 1/3/83 6 2.6.2.0 -
1/3/84 1/3/95 7 2.6.2.0 -
1/3/96 1/3/107 8 2.6.2.0
Step 2 Find the version of firmware that is bundled with the Cisco IOS software. The Cisco AS5800 supports the show modem bundled-firmware command which replaces the show modem map command that displays the region of NVRAM that identifies where the modems get their firmware at bootup.
as5800-RS-1# show modem bundled-firmware
List of bundled modem firmware images by slot
Slot 4
2.6.2.0
Slot 5
2.6.2.0
Slot 6
2.6.2.0
Slot 7
2.6.2.0
Slot 8
2.6.2.0
Step 3 Inspect the directory that stores the bundled firmware files. The files are loaded into the system main memory through the system:/ucode directory.
In the following example, two versions of firmware are found: mica_port_firmware and microcom_firmware. The file mica_board_firmware is not user upgradeable.
5800-NAS# dir system:ucode
Directory of system:/ucode/
14 -r-- 516060 <no date> mica_board_firmware
15 -r-- 375525 <no date> mica_port_firmware
16 -r-- 381284 <no date> microcom_firmware
No space information available
Step 4 Look at the existing contents of Flash/bootFlash for the following reasons:
Determine what firmware versions you already have.
Determine if your Flash/bootFlash is read-only or read/write.
Determine if you have enough free space.
The commands show flash and show bootflash are supported in any version of Cisco IOS software. The commands dir flash: and dir bootflash: are supported in Cisco IOS Release 12.0T.
4096K bytes of processor board Boot flash (Read/Write)
Filenames are arbitrary and are not necessarily indicative of their contents. If there is not enough free space on Flash or bootFlash to store the desired file, then you need to:
a. Copy the existing files that you want to keep onto a TFTP server.
b. Erase the Flash memory.
c. Copy the desired files into Flash memory.
Upgrading Modem Firmware
Cisco regularly enhances modem DSP code to improve modem performance. To obtain the latest DSP code, upgrade the NAS modem firmware.
Figure 3-12 summarizes the firmware upgrade procedure.
Figure 3-12 Modem Firmware Download Operation Example
Step 2 Download the latest firmware from CCO to the NAS Flash or bootFlash memory. Depending on which Cisco IOS software you are running, there are two ways you can get the latest firmware from CCO into the NAS Flash or bootFlash. Table 3-8 describes these two methods.
Table 3-9 Firmware Copy Commands
Cisco IOS Software Release
Command
Purpose
12.0T and later
copy ftp
Copy a file directly from CCO into Flash memory, without staging it at a local TFTP server.
11.3 and later
copy tftp: {flash: | bootflash:}
Copy from a TFTP server.
The following example uses the copy ftp command. The file mica-modem-pw.2.7.1.0.bin is copied from ftp.cisco.com to the bootFlash. Be sure to specify your own CCO username and password in the command line (as indicated in the example).
5800-NAS# ping ftp.cisco.com
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.31.7.171, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
392241 bytes copied in 5.940 secs (78448 bytes/sec)
5800-NAS#
Step 3 Verify that the new firmware is in Flash or bootFlash memory. The unbundledfirmware file is mica-modem-pw.2.7.1.0.bin in this example.
5800-NAS# dir flash:
Directory of flash:/
1 -rw- 4583276 <no date> C5800-IS-MZ.113-9_AA
2 -rw- 4675992 <no date> c5800-js-mz.112-18.P.bin
3 -rw- 392241 <no date> mica-modem-pw.2.7.1.0.bin
4 -rw- 5947548 <no date> c5800-is-mz.120-4.XI1
5 -rw- 4339 <no date> startup-config.12.0(4)XI1
16777216 bytes total (1173496 bytes free)
Step 4 (Optional) Enable the modem firmware-download command to watch the modem mapping operation take place:
5800-NAS# modem firmware-download
Modem Firmware-Download debugging is on
Step 5 Map the new firmware to the modems.
For MICA modems, firmware is mapped to entire modem modules (6 or 12 modem-module boundaries; not individual modems). For Microcom modems, firmware is mapped to one or more individual modems. The rule requiring that all modems in a MICA module run the same code is an architectural requirement.
Depending on which Cisco IOS release is loaded in the NAS, there are two commands that you can use. Table 3-10 describes these two commands.
Table 3-10 Modem Mapping Commands
Cisco IOS Software Release
Command
Notes
12.0(5)T and later
spe
An SPE unit is defined as the smallest software downloadable unit. For Microcom, an SPE is an individual modem.
For MICA, an SPE is either 6 or 12 modems, depending on whether the MICA module is single or double density.
Before Release 12.0(5)T
copy source modem
Replace the source variable with either flash or bootflash.
The following MICA example uses the spe command. The numbers 1/0 1/7 refer to modem modulenumbers 0 through 7 in slot 1. These numbers do not refer to specific modem numbers (for example, slot/port for Microcom modems). In this example, 48 modems are upgraded (8 SPE x 6 modems per module = 48 modems).
5800-NAS# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
In this example, the specified SPE range gets updated with new firmware in batches of six modems at a time. If double density modems were installed, batches of 12 modems would be updated.
Note The SPE range 1/0 to 1/7 is mapped to firmware 2.7.1.0. However, SPE range 2/0
through 2/7 is still mapped to the firmware that is bundled with the Cisco IOS
software.
The following MICA example is for the copy source modem command. Unlike the spe command, the numbers 1/0-1/5 refer to specific modem numbers (slot/port). The busyout keyword will gracefully busy out the modems if the modems are off hook.
cisco# copy bootflash modem
Source filename []? mica-modem-pw.2.6.2.0.bin
Modem Numbers (<slot>/<port> | group <number> | all)? 1/0-1/5
Type of service [busyout/reboot/recovery] busyout
Allow copy of "bootflash:mica-modem-pw.2.6.2.0.bin" to modems? [yes/no]yes
5800#
2d05h: %MODEM-5-DL_START: Modem (1/0) started firmware download
2d05h: %MODEM-5-DL_START: Modem (1/1) started firmware download
2d05h: %MODEM-5-DL_START: Modem (1/2) started firmware download
2d05h: %MODEM-5-DL_START: Modem (1/3) started firmware download
2d05h: %MODEM-5-DL_START: Modem (1/4) started firmware download
2d05h: %MODEM-5-DL_START: Modem (1/5) started firmware download
Step 6 Verify that the new firmware was successfully mapped to the modems.
In the following example:
SPE 1/0 applies to modems 1/0 through 1/5.
SPE 1/1 applies to modem 1/6 through 1/11, and so on.
The MICA modules 0 through 7 in slot 1 are running Version 2.7.1.0 (not 2.6.2.0).
All the modems in slot 2 are still running version 2.6.2.0, which is bundled into the Cisco IOS software image (see the field IOS-Default).
as5800-RS-1# show modem bundled-firmware
List of bundled modem firmware images by slot
Slot 4
2.6.2.0
Slot 5
2.6.2.0
Slot 6
2.6.2.0
Slot 7
2.6.2.0
Slot 8
2.6.2.0
Configuring Modems Using Modem Autoconfigure
This section describes how to apply a new modem capability (modemcap) to an integrated modem. A modemcap is a database of setup strings that is used by the modem autoconfigure function to change a modem's default settings.
Modemcaps have many applications:
A modem's default settings are not optimal. For example, a modem function that you want is not enabled by default.
Two separate modem pools need to be set up in the NAS to perform two different tasks. For example, one pool supports V.90. The other pool has a maximum speed set at 26400 bps to support older modems.
A specialized application is required. For example, a NAS supporting a point-of-sale (POS) application such as a charge card reader. A modemcap is required that will tune the modem for a fast trainup time at the expense of having a slower connect speed.
Always use a modemcap (even if you only want the modem's default settings). To display the modemcaps that are built into the Cisco IOS software, enter the show modemcap command. Modemcaps are configured on a per modem basis. They are not configured on a per modem module or service processing element (SPE) basis.
Basic Rules for Modem Autoconfigure
The following list describes the basic rules:
Never use the modem autoconfigure discovery command. Applying specific modemcaps reduces the risk of error.
Always use the modem autoconfigure typemodem-name command. This command improves your modem's performance.
The modem autoconfigure type mica command can be used to reset any integrated modem (not only MICA), back to its factory defaults. The keyword mica is a built-in modemcap that only functions as &F (return to defaults).
When you use the modem autoconfigure command, be sure that any script reset function is removed. A script reset is redundant and possibly harmful.
A script reset is a chat script that is applied to a line when the line resets. The modem autoconfigure function is applied when the system starts up, not just when the line resets.
When creating a modemcap, ignore all the strange and confusing fields. Put your modem init string into the MSC (Miscellaneous) field:
Always start your init string with &F (or, for third party modems, with the preferred &F1, &F2, etc.)
Never put an &W into an init string. An &W can wear out the EPROM on modems where this is not a no op (that is, a statement or operation that does nothing).
For MICA modems, always be sure that &D2 (not &D3) is in effect.
Modem Autoconfigure K56Flex Example
The following modem-autoconfigure string disables V.8bis/K56Flex. The string &F&D2s53=0 is applied to two MICA modems. Disabling V.8bis reduces trainup time by about two seconds, and it prevents trainup problems with older client modems.
Step 1 Watch the modem autoconfigure function run, so you can see if there are any typos in the modem string:
5800-NAS# debug confmodem
Modem Configuration Database debugging is on
5800-NAS# show debug
Modem Autoconfig:
Modem Configuration Database debugging is on
5800-NAS# terminal monitor
Step 2 Remove any previous modem autoconfigure entry:
5800-NAS# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Step 4 Apply the new entry to the specified lines. Re-enter the modem autoconfigure command each time you change a modemcap. Modem-autoconfigure strings are not applied to busy modems. Modem strings are applied after modems disconnect.
5800-NAS(config)# line 1 2
5800-NAS(config-line)# modem autoconfigure type mica-noKflex
5800-NAS(config-line)#
Oct 25 19:46:06.960 PDT: TTY1: detection speed (115200) response ---OK---
Oct 25 19:46:06.960 PDT: TTY1: Modem command: --AT&F&D2s53=0--
Oct 25 19:46:06.960 PDT: TTY2: detection speed (115200) response ---OK---
Oct 25 19:46:06.960 PDT: TTY2: Modem command: --AT&F&D2s53=0--
Oct 25 19:46:09.520 PDT: TTY1: Modem configuration succeeded
Oct 25 19:46:09.520 PDT: TTY1: Detected modem speed 115200
Oct 25 19:46:09.520 PDT: TTY1: Done with modem configuration
Oct 25 19:46:09.520 PDT: TTY2: Modem configuration succeeded
Oct 25 19:46:09.520 PDT: TTY
5800-NAS(config-line)#
If you want to reset the modem to its factory defaults, do not simply remove the modem autoconfigure command. Rather, replace it with another modem autoconfigure typename command where name is a modemcap whose only action is &F. (In recent Cisco IOS software releases, the built-in mica modemcap entry will do this.)
Gathering and Viewing Call Statistics
Making sure that your modems are connecting at the correct connections speeds is an important aspect of managing modems. This section details the following methods for gathering and viewing modem performance statistics:
Note If you detect low connection speeds across all the modems, you may have a faulty
channelized T1/E1 or ISDN PRI line connection.
Using the Cisco IOS EXEC (CLI)
The Cisco IOS software command line interface (CLI) contains many modem management show commands. Use these commands to gather and view modem statistics. This section provides a bulleted list detailing some of the most useful commands.
Step 1 List show modem command options:
AS5800-1# show modem ?
<0-1439> First Modem TTY Number
bundled-firmware Bundled modem firmware information for all modem slots
call-stats Calling statistics for all system modems
calltracker CallTracker modem information
config Modem configuration
connect-speeds Connection speeds for all system modems
csm CSM modem information
group Modem group information
log Modem event log
operational-status Modem operational status
summary Summary statistics for all system modems
test Modem test log
version Version information for all system modems
x/y/z First Shelf/Slot/Port for Internal Modems
| Output modifiers
<cr>
Step 2 Display a summary of the modem call statistics:
5800-NAS# show modem summary
Incoming calls Outgoing calls Busied Failed No Succ
Usage Succ Fail Avail Succ Fail Avail Out Dial Ans Pct.
43% 60005 4678 25 3 11 0 0 13 8 92%
Table 3-11 describes some of the significant fields in the previous example.
Table 3-11 Show Modem Summary Field Descriptions
Field
Description
Succ 60005
60,005 calls successfully trained up. The Cisco IOS software saw "DSR" go high (still does not mean that PPP negotiated successfully).
Fail 4678
4,678 calls came into the modem, the modem went offhook, but the modem did not train up.
Succ Pct. 92%
The overall success percentage is 92%.
No Ans 8
Eight calls came into the modem but the modem did not go offhook (CPU was too busy). Unless you misconfigured the NAS, this counter should be very low (under 1% of the total calls).
Step 3 Display the disconnect reasons for the modems that trained up:
Table 3-12 describes some of the significant fields in the previous example.
Table 3-12 Show Modem Call-Status Field Descriptions
Field
Description
rmtLink 9999
RmtLink is the most common disconnect reason. RmtLink means that the modem trained up, error correction was negotiated, and the client DTE decided to hang up. All the call-stat counters do not go higher than 9999.
hostDrop
HostDrop (or dtrDrop) means the Cisco IOS software (DTE) informed the modem to terminate the call. For example:
Idle timeouts
Absolute timeouts
Authentication failures
PPP negotiation failures
The Cisco IOS software learns from the telephone switch that the DS0 was disconnected.
Besides the "hostDrop" message, all other disconnect reasons are not good. If the call trained up without EC, then the peer modem will probably not communicate an orderly disconnect with the Cisco IOS software. For example, the messages "lostCarr" or "retrain" might be displayed even though the peer DTE voluntarily disconnected. The collective total of disconnect reasons should be less than 10% of the total number of calls.
Step 4 Look at detailed disconnect reasons for individual modems:
Step 5 Display a summary of the range of connect speeds. Specify the top speed of interest followed by a 0. This example displays the initial connect speeds in each direction (transmit and receive) for the range of speeds that go up to 56K. No connections happened at 56000 bps. The transmit speed with the highest hit counter is 48K (9161 hits). The receive-connect speeds are all zeros because V.90 is a transmit only speed.
Step 6 Inspect the range of speeds below 56000 bps (38667 to 46667). This is the distribution of speeds of PCM users (Kflex users and V.90 users). Compare this output with the previous example. The peak speed is at 48K, which had 9,161 hits—15% of all callers.
Step 7 Examine the DS0 timeslots on each T1 that are used to carry the modem calls. The following example shows that the telco is distributing calls into this hunt group evenly across the T1s. There are a total of 29 (20+9) DS0s currently active.
The high-water mark reports the highest number of DS0s that were in use at one time. However, be sure to inspect the entire dial pool. Entire T1s have been known to remain idle in some hunt groups.
5800-NAS# show controllers t1 call-counters
T1 0:
DS0's Active: 20
DS0's Active High Water Mark: 23
TimeSlot Type TotalCalls TotalDuration
1 pri 6536 3w1d
2 pri 6701 2w3d
3 pri 5789 2w0d
4 pri 5498 1w2d
5 pri 5497 3d02h
6 pri 5126 7w0d
7 pri 4525 6w1d
8 pri 4401 5w3d
9 pri 4096 4w4d
10 pri 3961 3w3d
11 pri 3320 3w0d
12 pri 3138 1w3d
13 pri 2912 4d05h
14 pri 2486 6w4d
15 pri 2042 5w5d
16 pri 1644 4w5d
17 pri 1413 4w1d
18 pri 1071 3w3d
19 pri 884 2w4d
20 pri 675 2w0d
21 pri 507 1w3d
22 pri 380 1w1d
23 pri 263 5d17h
T1 1:
DS0's Active: 9
DS0's Active High Water Mark: 23
TimeSlot Type TotalCalls TotalDuration
1 pri 8985 3w2d
2 pri 8650 2w4d
3 pri 8594 1w3d
4 pri 7813 4d03h
5 pri 7671 6w3d
6 pri 6955 5w5d
7 pri 6492 4w3d
8 pri 6343 3w4d
9 pri 5668 2w3d
10 pri 5398 6d09h
11 pri 4842 6w6d
12 pri 4413 5w3d
13 pri 4050 4w1d
14 pri 3339 2w6d
15 pri 3019 1w2d
16 pri 2493 1d14h
17 pri 2104 6w0d
18 pri 1664 5w1d
19 pri 1395 3w6d
20 pri 1094 3w3d
21 pri 811 2w6d
22 pri 688 2w0d
23 pri 482 1w3d
Total DS0's Active High Water Mark: 46
Using Modem Call-Record Terse
Starting with Cisco IOS Releases 11.3AA and 12.0T, modem call records can be sent to syslog and examined to perform statistical analysis.
For example, you can monitor:
Modulation trends such as V.90 verses V.34
Call time durations (consistent short connection times on a modem, regular Lost Carrier counts)
Unavailable user IDs
PPP negotiation or authentication failures
The following example enables modem call-records and sends the logs to wherever your syslog output goes, for example:
To the console—If you do not have the no logging console command enabled.
To the terminal line—If you have the terminal monitor command enabled.
To a syslog host—If you have one configured.
5800-NAS# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Modem connect speeds can be graphed using SNMP MIBs. The graph shown in Figure 3-13 was created with Cisco Access Manager (CAM). The graph describes the modem connect-speed performance activity of one NAS for one month. The following connect speeds are transmitted by the NAS and received by the client modem. Most of the calls performed between 28000 and 31200 bps. This NAS is one member of an access stack.
For discussions on enabling management protocols such as NTP, SNMP, and Syslog, refer to "Administration."
Figure 3-13 Graphed Modem-Connect Speeds for One Month
