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Table of Contents

Monitoring and Managing Connections

Monitoring and Managing Connections

This chapter describes how to monitor and manage your network connections. The "Monitoring Connections" section describes the show commands and procedures that you use to monitor network devices and activities, including showing the status of all sessions or active ports on the networking hardware. The "Managing Connections" section describes session management activities.

Monitoring Connections

The following sections describe the show commands and procedures used to monitor network devices and activities for the supported transmission protocols:


Note The various show commands described in these sections are only a subset of the available monitoring commands for each protocol. For information about additional monitoring commands for a given protocol, refer to the command reference publication for your server product.

Enter all monitoring commands at the user EXEC prompt.

Monitoring Commands Generic to All Protocols

This section describes the following commands, which are generic to all connection protocols:

show sessions and where

You can display information about open LAT, Telnet, or rlogin connections by issuing either of the following commands:

show sessions

where

These commands display the host name, address, number of unread bytes for the user to see, idle time, and connection name.

Sample Display

The following is sample output from the show sessions command:

sloth# show sessions Conn Host Address Byte Idle Conn Name 1 MATHOM 192.31.7.21 0 0 MATHOM * 2 CHAFF 131.108.12.19 0 0 CHAFF

The asterisk (*) indicates the current terminal session.

Table 6-1 describes significant fields shown in the display.


Table 6-1: Show Sessions Field Descriptions
Field Description

Conn

Name or address of the remote host to which the connection is made.

Host

Remote host to which the router is connected through a Telnet session.

Address

IP address of the remote host.

Byte

Number of unread bytes for the user to see on the connection.

Idle

Interval (in minutes) since data was last sent on the line.

Conn Name

Assigned name of the connection.

show hosts

Use the show hosts command to display the default domain name, the style of name lookup service, a list of name server hosts, and the cached list of host names and addresses on the network to which you can connect.

show hosts

Sample Display

The following is a sample display from the show hosts output:

sloth# show hosts Default domain is CISCO.COM Name/address lookup uses domain service Name servers are 255.255.255.255 Host               Flag         Age    Type        Address(es) SLAG.CISCO.COM     (temp, OK)   1      IP          131.108.4.10 CHAR.CISCO.COM     (temp, OK)   8      IP          192.31.7.50 CHAOS.CISCO.COM    (temp, OK)   8      IP          131.108.1.115 DIRT.CISCO.COM     (temp, EX)   8      IP          131.108.1.111 DUSTBIN.CISCO.COM  (temp, EX)   0      IP          131.108.1.27 DREGS.CISCO.COM    (temp, EX)   24     IP          131.108.1.30

Table 6-2 describes significant fields shown in the display.


Table 6-2: Show Hosts Field Descriptions
Field Description

Host

Name of server host.

Flag

A temporary entry is entered by a name server; the server removes the entry after 72 hours of inactivity.

A permanent entry is entered by a configuration command and is not timed out. Entries marked OK are believed to be valid. Entries marked ?? are considered suspect and subject to revalidation. Entries marked EX are expired.

Age

Indicates the number of hours since the router last referred to the cache entry.

Type

Identifies the type of address, for example, IP, CLNS, or X.121. If you used the ip hp-host global configuration command, the show hosts command displays these host names as type HP-IP.

Address(es)

Shows the address of the host. One host can have up to eight addresses.

show users and systat

You can display information about the active lines on the server product. Issue either of the following commands:

show users [all]

systat [all]


These commands display the same information, including the line number, connection name, idle time, and terminal location.

Syntax Description

all

(Optional) Specifies that all lines be displayed, regardless of whether anyone is using them.

Sample Display

The following is sample output from the show users command:

sleepy# show users       Line           User            Host(s)        Idle Location       0 con 0                        idle *     2 vty 0        rose            idle            0   BASHFUL.CISCO.COM

The following is sample output from the show users all command:

sleepy# show users all    Line       User          Host(s)      Idle  Location *   0 vty 0    rose          idle         0    BASHFUL.CISCO.COM     1 vty 1    2 con 0    3 aux 0    4 vty 2

The asterisk (*) indicates the current terminal session.

Table 6-3 describes significant fields shown in the displays.


Table 6-3: Show Users Field Descriptions
Field Description

Line

Contains three subfields, as the first entry indicates.

The first subfield (0 in the sample) is the absolute line number.

The second subfield (vty) indicates the type of line. Possible values follow:

  • con—Console

  • aux—Auxiliary port

  • tty—Asynchronous terminal port

  • vty—Virtual terminal

The third subfield (0 in the current line (*) sample) indicates the relative line number within type.

User

User using the line. If no user is listed in this field, no one is using the line.

Host(s)

Host to which the user is connected (outgoing connection). A value of idle indicates no outgoing connection to a host.

Idle

Interval (in minutes) since the user has typed something.

Location

Either the hard-wired location for the line or, if there is an incoming connection, the host the incoming connection is from.

show entry

Use the show entry command to display the list of queued host-initiated connections to a server product. You can use this command to determine which LAT hosts have queue entries for printers on server products.

show entry

Sample Display

The following is sample output from the show entry command:

sloth# show entry 1 waiting 0:02:22 for port 5 from LAT node BLUE 2 waiting 0:00:32 for port 5 from LAT node STELLA

The display shows that two LAT connections are waiting for access to port 5. The list is ordered so that the lower-numbered entry, which has waited longer, gets to use the line next. The display shows how long each connection attempt has been waiting, for which port, and the user's name.

Table 6-4 describes the fields in the first line of output shown in the display.


Table 6-4: Show Entry Field Descriptions
Field Description

1

Number assigned to the queued connection attempt

waiting 0:02:22

Interval (hours:minutes:seconds) the connection attempt has been waiting

for port 5

Port for which the connection attempt is waiting

from LAT node BLUE

Name of the user attempting to make the connection

show terminal

You can display information about the current terminal line such as the line number, line status, modem state, and special characters set. This can be useful for changing lines to match expected settings using the local terminal parameter-setting tasks described in the "Changing Terminal Parameters" chapter in this publication. To display local terminal settings, issue the following command:

show terminal

The display includes a comprehensive report on the terminal settings in effect, including the preferred transport protocol.


Note In screen output examples showing two caret (^^) symbols together, the first caret represents the Control key and the second caret represents the keystroke sequence Shift-6. The double caret combination (^^) means hold down the Control key while you press the Shift and the 6 key.
Sample Display

The following is sample output from the show terminal command:

sloth# show terminal Line 2, Location: "", Type: "" Length: 24 lines, Width: 80 columns Baud rate (TX/RX) is 9600/9600 Status: Ready, Active, No Exit Banner Capabilities: Enabled Modem state: Ready Special Chars: Escape Hold Stop Start Disconnect Activation ^^x none - - none Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch never never 0:00:15 not imp not set Session limit is not set. Allowed transports are telnet rlogin. Preferred is telnet No output characters are padded

The first three lines of output shown in the display follow:

Line 2, Location: "", Type: "" Length: 24 lines, Width: 80 columns Baud rate (TX/RX) is 9600/9600

Table 6-5 describes the fields in the first three lines of show terminal output.


Table 6-5: Show Terminal Field Descriptions—First Three Lines of Output
Field Description

Line

Current terminal line.

Location

Location of the current terminal line, as specified by the location configuration command.

Type

Type of the current terminal line, as specified by the line global configuration command.

Length

Length of the terminal display.

Width

Width of the terminal display.

Baud rate (TX/RX)

Transmit rate/receive rate of the line.

The following line of output indicates the status of the line:

Status: Ready, Active, No Exit Banner

In this example, Ready, Active, and No Exit Banner are possible values for the Status field.

Table 6-6 shows all possible values for the Status field.


Table 6-6: Show Terminal Field Description—Status Field
Field Description

Active

A process is actively using the line.

Autobauding

The line is running the autobaud process.

Carrier Dropped

Some sense of "carrier" was dropped, so the line process should be killed.

Connected

The line has at least one active connection.

Dialing Out

A DDR asynchronous interface is dialing a remote site on the line.

Echo Off

The line is not echoing what the user types in (because a password must be entered, for example).

Escape Started

The first character of the escape sequence was typed.

Escape Typed

Both characters of the escape sequence have been typed.

Hanging Up

The line state is "hanging up."

Hardware XON/XOFF

The line uses a UART that supports XON/XOFF flow control in hardware. This does not mean that the line is currently using software flow control.

Hold Typed

The user typed the "hold character" (and the line is paused).

Idle

The line modem state is "idle."

Idle Timeout

An idle timeout has occurred.

Input Stopped

The input was turned off due to hardware flow control or overflow.

No Exit Banner

The normal exit banner will not be displayed on this line.

PSI Enabled

The line is paying attention to typed escape characters.

Rcvd BREAK

A BREAK sequence was received on the line.

Rcvd Command

The line has received a special command sequence (^^B for SEND BREAK, for example).

Rcvd CR

The last character received was a carriage return.

Ready

The line state is "ready."

Ring Transition

There was a transition on the RING signal of the line.

Send Break Soon

A BREAK must be sent on the line soon.

Send XOFF Soon

The buffers are full and an XOFF must be sent soon.

Sending Break

A BREAK sequence is in the process of being sent on the line.

Sent XOFF

The buffers were full, so an XOFF was sent.

Async Mode

The line is running SLIP or PPP.

The following line of output indicates the status of the capabilities of the line; these capabilities correspond closely to configurable parameters that can be set using configuration commands.

Capabilities: Enabled

Table 6-7 describes possible values for the Capabilities field.


Table 6-7: Show Terminal Field Descriptions—Capabilities Field
Field Descriptions

Autobaud Full Range

Corresponds to the autobaud line configuration command.

Character Padding

Indicates at least one pad configuration command was used.

Enabled

Indicates that the user has "enabled" successfully.

EXEC Suppressed

Corresponds to the no exec configuration command.

Hangup on Last Close

Corresponds to the autohangup line configuration command.

Hardware Flowcontrol In

Corresponds to the flowcontrol hardware in line configuration command.

Hardware Flowcontrol Out

Corresponds to the flowcontrol hardware out line configuration command.

Insecure

Corresponds to the insecure line configuration command.

Lockable

Corresponds to the lockable line configuration command.

Modem Callin

Corresponds to the modem callin line configuration command.

Modem Callout

Corresponds to the modem callout line configuration command.

Modem CTS-Required

Corresponds to the modem cts-required line configuration command.

Modem DTR-Active

Corresponds to the modem dtr-active line configuration command.

Modem RI is CD

Corresponds to the modem ri-is-cd line configuration command.

No Login Banner

Corresponds to the no exec-banner line configuration command.

Notification Set

Corresponds to the notify line configuration command.

Output Non-Idle

Corresponds to the session-timeout N output line configuration command.

Permanent Async

Corresponds to the dedicated-async line configuration command.

Private Line

Corresponds to the private line configuration command.

Refuse Suppress-GA

Corresponds to the telnet refuse line configuration command.

Receives Logging Output

Corresponds to the monitor configuration line configuration command.

Refuse Telnet Echo

Corresponds to the telnet refuse line configuration command.

Send BREAK on IP

Corresponds to the telnet break-on-ip line configuration command.

SLIP allowed

Corresponds to the slip address xxxx line configuration command.

Software Flowcontrol In

Corresponds to the flowcontrol software in line configuration command.

Software Flowcontrol Out

Corresponds to the flowcontrol software out line configuration command.

Telnet Transparent Mode

Corresponds to the telnet transparent line configuration command.

The following line of output indicates the modem state. Possible values include Autobauding, Carrier Dropped, Hanging Up, Idle, and Ready.

Modem state: Ready

The following lines of output indicate the special characters that can be entered to activate various terminal operations. Where two caret (^^) symbols are shown together, the first caret represents the Control key and the second caret represents the keystroke sequence Shift-6. The double caret combination (^^) means hold down the Control key while you press the Shift and the 6 key. The none or hyphen (-) values imply that no special characters are set.

Special Chars: Escape Hold Stop Start Disconnect Activation ^^x none - - none

The following lines of output indicate the timeout values that have been configured for the line:

Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch never never 0:00:15 not imp not set

Table 6-8 describes the fields in the preceding lines of output.


Table 6-8: Show Terminal Field Descriptions—Timeouts Fields
Field Descriptions

Idle EXEC

Interval the EXEC command interpreter waits for user input before resuming the current connection, or if no connections exist, returning the terminal to the idle state and disconnecting the incoming session. This interval is set using the exec-timeout line configuration command.

Idle Session

Interval that the server product waits for traffic before closing the connection to a remote computer and returning the terminal to an idle state. This interval is set using the session-timeout line configuration command.

Modem Answer

Interval during which the server product raises DTR in response to RING and the modem response to CTS. This interval is set using the modem answer-timeout line configuration command.

Session

Not implemented in this release.

Dispatch

Number of milliseconds the server product waits after putting the first character into a packet buffer before sending the packet. This interval is set using the dispatch-timeout configuration command.

The following lines of output indicate how various options have been configured:

Session limit is not set. Allowed transports are telnet rlogin. Preferred is telnet No output characters are padded

LAT Show Commands

This section describes the following commands, which monitor LAT connections:

show service

Use the show service command to display specific LAT learned services:

show service [service-name]

Syntax Description

service-name

(Optional) Name of a specific LAT service.

The show service command without a service name displays a list of known LAT learned services. When entered with the service-name argument, it displays a more detailed status of the named service. If no LAT learned service by the specified name is known, a lookup is done for an IP host of that name.

Sample Display

The following is sample output from the show service command:

cs> show service Service Name Status     Identification BLUE         Available   Welcome to VAX/VMS V5.4 CHAOS       Available MRL12       Available MUDDY-RIVER  Available STELLA-BLUE  Available   Welcome to VAX/VMS V5.4

The following is sample output from the show service command for a specified service:

cs> show service blue Service BLUE - Available Node Name Status    Rating    Identification BLUE      reachable 84         Welcome to VAX/VMS V5.4

Table 6-9 describes significant fields shown in the two previous displays.


Table 6-9: Show Service Field Descriptions
Field Description

Service Name

Name of the service.

Status

Status of the service: Available or Unknown when the command is entered without a service name. Available, Unknown, Initializing, or Unreachable when the command is entered with a service name.

Identification

Identification string.

Node Name

Name of the nodes advertising the service.

Rating

Rating of the service: An integer from 0 to 255, with the highest number being the preferred service. Used for load balancing.

show lat services

Use the show lat services command on a server product to display information on learned LAT services.

show lat services

Sample Display

The following is sample output from the show lat services command:

sloth# show lat services Service Name Rating Interface Node (Address) ABCDEFGHIJ 5 Ethernet0 CONFUSED (0000.0c00.391f) GLAD 84 Ethernet0 BLUE (aa00.0400.9205) Ident: Welcome to Big Blue Gateway WHEEL 83 Ethernet0 WHEEL (aa00.0400.9005) ZXYW 5 Ethernet0 CONFUSED (0000.0c00.391f)

Table 6-10 describes significant fields shown in this display.


Table 6-10: Show LAT Services Field Descriptions
Field Description

Service Name

LAT service name.

Rating

Rating of the service. If a single service is provided by more than one host, the server product connects to the one with the highest rating.

Interface

Interface type.

Node

Connection address.

(Address)

Advertised identification for the service.

show lat sessions

The EXEC command show lat sessions displays active LAT sessions. The command has the following syntax:

show lat sessions [line-number]

Syntax Description

line-number

(Optional) Shows an active LAT session on a specific line.

Sample Display

The following is sample output from the show lat sessions command. In this example, information about all active LAT sessions is displayed. The output is divided into three sections for each session (in this case two): TTY data, session data, and remote node data.

cs> show lat sessions tty0, connection 1 to service TERM1 TTY data: Name "0", Local usage 1/0, Remote usage disabled Flags: Local Connects, Enabled Type flags: none Config flags: -FlowOut, -FlowIn, Parameter Info Flow control ^S/^Q in ^S/^Q out, Mode Normal, Parity None, databits 8 Groups: 0 Session data: Name TERM1, Remote Id 1, Local Id 1 Remote credits 2, Local credits 0, Advertised Credits 2 Flags: none Max Data Slot 255, Max Attn Slot 255, Stop Reason 0 Remote Node data: Node "TERM1", Address 0000.0C00.291F, usage 1 Timer 59, sequence 5, changes 159, flags 0x0, protocol 5.1 Recv 56/22/83, Xmit 41/23/14, 0 Dups, 0 ReXmit Groups: 0 tty10, connection 1 to service ENG2 TTY data: Name "10", Local usage 1/0, Remote usage disabled Flags: Local Connects, Enabled Type flags: none Config flags: -FlowOut, +FlowIn, Set Parameters, 0x40000000 Flow control ^S/^Q in ^S/^Q out, Mode Normal, Parity None, databits 8 Groups: 0 Session data: Name ENG2, Remote Id 1, Local Id 1 Remote credits 1, Local credits 0, Advertised Credits 2 Flags: none Max Data Slot 255, Max Attn Slot 255, Stop Reason 0 Remote Node data: Node "ENG2", Address AA00.0400.34DC, usage 1 Timer 179, sequence 60, changes 255, flags 0x0, protocol 5.1 Recv 58/29/186, Xmit 50/36/21, 0 Dups, 0 ReXmit Groups: 0

The following sample output displays information about active LAT sessions on one line, line 10. The output is divided into three sections: TTY data, session data, and remote node data.

cs# show lat sessions 10 tty10, connection 1 to service ENG2 TTY data: Name "10", Local usage 1/0, Remote usage disabled Flags: Local Connects, Enabled Type flags: none Config flags: -FlowOut, +FlowIn, Set Parameters, 0x40000000 Flow control ^S/^Q in ^S/^Q out, Mode Normal, Parity None, databits 8 Groups: 0 Session data: Name ENG2, Remote Id 1, Local Id 1 Remote credits 1, Local credits 0, Advertised Credits 2 Flags: none Max Data Slot 255, Max Attn Slot 255, Stop Reason 0 Remote Node data: Node "ENG2", Address AA00.0400.34DC, usage 1 Timer 189, sequence 61, changes 247, flags 0x0, protocol 5.1 Recv 60/29/186, Xmit 52/36/21, 0 Dups, 0 ReXmit Groups: 0

Table 6-11 describes the screen output for the preceding two examples.


Table 6-11: Show LAT Session Status Display Field Descriptions
Field Description
TTY data

Summary of the LAT-oriented terminal-line specific data.

Name

Name used for this port as a port identification string. The name is reported to remote systems, which may display it in some operating-system dependent manner. This value is also used for targets of host-initiated connections. Currently, this value is hard-wired to be the line number of the associated terminal line.

Local/Remote usage

Current status of the terminal. The number is reported as current/maximum, where current is the current number of sessions of a given type, and maximum is the maximum number of sessions allowed, or zero if there is no maximum. If a terminal is being used for outgoing sessions, the local usage is equal to the number of current LAT sessions. If the terminal is being used for incoming sessions, local usage will be disabled, and the remote count and maximum will be one.

Flags

Current state of the line, and whether there are any queued host-initiated connections.

Type flags

Report flags not used in the current software release.

Config flags

Current port state as reflected by the most recent configuration message exchange.

Flow control

Lists set flow control characters.

Groups

Group code list currently in use for the line.

Session data

Reports various parameters about the connection.

Name

For the outbound connection, the name of the remote service to which it is connected. For inbound connections, this field is currently unused.

Remote/Local ID

Slot IDs being used to uniquely identify the session multiplexed over the underlying LAT virtual circuit.

Remote/Local/
Advertised Credits

Number of flow control credits that the server product will be sending to the host as soon as possible. The advertised credits are the number of credits that have already been extended.

Flags

Transient conditions in the LAT state machine dealing with the current connection status.

Max Data Slot

Maximum number of characters that can be sent in a single data slot.

Max Attn Slot

Maximum amount of data that can be sent in an attention message because current LAT implementations only send one-byte attention messages (attention messages are used to flush buffered output); a nonzero value means that remote data flushing can be used; a zero means that it cannot.

Stop Reason

Reason the session was stopped, if it was stopped but not deleted. This value is usually zero, indicating that the session has not been stopped yet. If a session persists for a long time with a nonzero stop reason, this generally indicates a problem in the local LAT software.

Remote Node data

Reports information about the remote node. The data includes the same fields as those from the show lat nodes output.

Node

Node name as reported by the host computer.

Address

MAC address of the node's Ethernet interface.

usage

Number of virtual circuits currently active to the node.

Timer

Number of seconds remaining until the node's service advertisement message will time out; this value is set to three times the nodes multicast timer value whenever a new service advertisement message is received.

sequence

Sequence number received in the last service advertisement message received. Nodes increment their sequence number when the contents of the service advertisement change.

changes

Internal representation of what changed in the multicast message the last time the sequence number changed.

flags

Internal representation of various state information about the node.

protocol

LAT protocol version used by the node.

Recv and Xmit

Number of messages, slots, and bytes received or transmitted to the node. The number of messages is the number of LAT virtual circuit messages. Each virtual circuit message contains some number of slots, which contain actual terminal data or control information.

Dups

Number of duplicate virtual circuit messages received.

ReXmit

Number of virtual circuit messages retransmitted.

Groups

Group codes advertised by the node's service advertisement message.

TCP/IP Show Command

This section describes the show tcp command.

show tcp

Use the show tcp command to display the status of a TCP connection.

show tcp [line-number]

Syntax Description

line-number

(Optional) Displays (in octal) the status of the TCP connections for a particular line.

Sample Display

The following is sample output from the show tcp command:

sloth# show tcp con0 (console terminal), connection 1 to host MATHOM Connection state is ESTAB, I/O status: 1, unread input bytes: 1 Local host: 192.31.7.18, 33537 Foreign host: 192.31.7.17, 23 Enqueued packets for retransmit: 0, input: 0, saved: 0 Event Timers (current time is 2043535532): Timer: Retrans TimeWait AckHold SendWnd KeepAlive Starts: 69 0 69 0 0 Wakeups: 5 0 1 0 0 Next: 2043536089 0 0 0 0 iss: 2043207208 snduna: 2043211083 sndnxt: 2043211483 sndwnd: 1344 irs: 3447586816 rcvnxt: 3447586900 rcvwnd: 2144 delrcvwnd: 83 RTTO: 565 ms, RTV: 233 ms, KRTT: 0 ms, minRTT: 68 ms, maxRTT: 1900 ms ACK hold: 282 ms Datagrams (max data segment is 536 bytes): Rcvd: 106 (out of order: 0), with data: 71, total data bytes: 83 Sent: 96 (retransmit: 5), with data: 92, total data bytes: 4678

Table 6-12 describes the following lines of output shown in the display:

con0 (console terminal), connection 1 to host MATHOM Connection state is ESTAB, I/O status: 1, unread input bytes: 1 Local host: 192.31.7.18, 33537 Foreign host: 192.31.7.17, 23 Enqueued packets for retransmit: 0, input: 0, saved: 0
Table 6-12: Show TCP Field Descriptions—First Section of Output
Field Description

con0

Line number.

(console terminal)

Location string.

connection 1

Number identifying the TCP connection.

to host MATHOM

Name of the remote host to which the connection is made.

Connection state is ESTAB

A connection progresses through a series of states during its lifetime. The states include the following:

  • LISTEN—Waiting for a connection request from any remote TCP and port.

  • SYNSENT—Waiting for a matching connection request after having sent a connection request.

  • SYNRCVD—Waiting for a confirming connection request acknowledgment after having both received and sent a connection request.

  • ESTAB—Indicates an open connection; data received can be delivered to the user. This is the normal state for the data transfer phase.

  • FINWAIT1—Waiting for a connection termination request from the remote TCP, or an acknowledgment of the connection termination request previously sent.

  • FINWAIT2—Waiting for a connection termination request from the remote TCP host.

  • CLOSEWAIT—Waiting for a connection termination request from the local user.

  • CLOSING—Waiting for a connection termination request acknowledgment from the remote TCP host.

  • LASTACK—Waiting for an acknowledgment of the termination request previously sent to the remote TCP host.

  • TIMEWAIT—Waiting for enough time to pass to be sure the remote TCP host has received the acknowledgment of its connection termination request.

  • CLOSED—Indicates no connection state at all.

For more information, see RFC 793, Transmission Control Protocol Functional Specification.

I/O status: 1

Number describing the internal status of the connection.

unread input bytes: 1

Number of bytes that the lower-level TCP processes have read, but the higher-level TCP processes have not yet processed.

Local host: 192.31.7.18

IP address of the network server product.

33537

Local port number, as derived from the following equation: line-number + (512 * random-number). The line number uses the lower nine bits; the other bits are random.

Foreign host: 192.31.7.17

IP address of the remote host to which the TCP connection was made.

23

Destination port for the remote host.

Enqueued packets for retransmit: 0

Number of packets waiting on the retransmit queue. These are packets on this TCP connection that have been sent but not yet acknowledged by the remote TCP host.

input: 0

Number of packets waiting on the input queue to be read by the user.

saved: 0

Number of received out-of-order packets waiting for all packets comprising the message to be received before they enter the input queue. For example, if packets 1, 2, 4, 5, and 6 have been received, packets 1 and 2 would enter the input queue, and packets 4, 5, and 6 would enter the saved queue.

The following line of output shows the current time according to the system clock of the local host.

Event Timers (current time is 2043535532):

The following lines of output display the number of times that various local TCP timeout values were reached during this connection. In this example, the server product retransmitted 69 times because it received no response from the remote host, and it transmitted a local acknowledgment many more times because there was no data on which to piggyback. Table 6-13 describes the fields in the following lines of output:

Timer: Retrans TimeWait AckHold SendWnd KeepAlive Starts: 69 0 69 0 0 Wakeups: 5 0 1 0 0 Next: 2043536089 0 0 0 0
Table 6-13: Show TCP Field Descriptions—Second Section of Output
Field Description

Timer

Names of the timers in the display.

Retrans

Determines how long a transmitted frame can remain unacknowledged before the server product polls for an acknowledgment.

TimeWait

Determines how long the local TCP connection waits to be sure the remote TCP host has received the acknowledgment of its connection termination request.

AckHold

Number of times the system failed to piggyback data on required a TCP acknowledgment. Such piggybacking can significantly reduce network traffic.

SendWnd

Timers have to do with sending "zero window probes." Essentially, this field reflects how often users send more data to the remote host than it can handle in the time it takes users to send it. For most normal server product applications, this value will likely stay zero.

KeepAlive

Determines the frequency (in seconds) at which the server product sends messages to itself (Ethernet and Token Ring) or to the other end (serial) to ensure that a network interface is alive. The keepalive interface configuration command is used to set this timer.

Starts

Number of times the timer was started during this connection.

Wakeups

Number of keepalives that have been transmitted without receiving any response. This field is reset to zero when a response is received.

Next:

System clock setting that triggers the next time this timer will go off.

The following lines of output display the sequence numbers that TCP uses to ensure sequenced, reliable transport of data. The server product and remote host each use these sequence numbers for flow control and to acknowledge receipt of datagrams. Table 6-14 describes the fields in this output.

iss: 2043207208 snduna: 2043211083 sndnxt: 2043211483 sndwnd: 1344 irs: 3447586816 rcvnxt: 3447586900 rcvwnd: 2144 delrcvwnd: 83
Table 6-14: Show TCP Field Descriptions—Sequence Numbers
Field Description

iss: 2043207208

Initial send sequence number.

snduna: 2043211083

Last send sequence number the server product has sent but for which it has not received an acknowledgment.

sndnxt: 2043211483

Sequence number the router will send next.

sndwnd: 1344

TCP window size of the remote host.

irs: 3447586816

Initial receive sequence number.

rcvnxt: 3447586900

Last receive sequence number the server product has ACKed.

rcvwnd: 2144

The server product's TCP window size.

delrcvwnd: 83

Delayed receive window—data the server product has read from the connection, but has not yet subtracted from the receive window the router has advertised to the remote host. The value in this field gradually increases until it is larger than a full-sized packet, at which point it is applied to the rcvwnd field.

The following lines of output show the values that the server product uses to keep track of transmission times so that TCP can adjust to the network it is using. Table 6-15 describes the fields in this output.

RTTO: 565 ms, RTV: 233 ms, KRTT: 0 ms, minRTT: 68 ms, maxRTT: 1900 ms ACK hold: 282 ms
Table 6-15: Show TCP Field Descriptions—Line Beginning with RTTO
Field Descriptions

RTTO: 565 ms

Round-trip timeout.

RTV: 233 ms

Variance of the round-trip time.

KRTT: 0 ms

New round-trip timeout (using the Karn algorithm). This field separately tracks the round trip time of packets that have been retransmitted.

minRTT: 68 ms

Smallest recorded round-trip timeout (hard wire value used for calculation).

maxRTT: 1900 ms

Largest recorded round-trip timeout.

ACK hold: 282 ms

Time the server product will delay an ACK in order to piggyback data on it.

For more information on these fields, refer to the article "Round Trip Time Estimation," by P. Karn and C. Partridge, ACM SIGCOMM-87, August 1987.

Table 6-16 describes the fields in the following lines of output:

Datagrams (max data segment is 536 bytes): 4761 Rcvd: 106 (out of order: 0), with data: 71, total data bytes: 83 Sent: 96 (retransmit: 5), with data: 92, total data bytes: 4678
Table 6-16: Show TCP Field Descriptions—Last Section of Output
Field Description

Datagrams

Datagrams sent and received on the line

Rcvd

Number of datagrams the local host has received during this connection (and the number of these datagrams that were our of order)

with data

Number of datagrams that contained data

total data bytes

Total number of bytes of data in the transmitted datagrams

Sent (and retransmitted)

Number of datagrams the local host sent during this connection (and the number of these datagrams that had to be retransmitted)

with data

Number of transmitted datagrams that contained data

total data bytes

Total number of bytes of data in the transmitted datagrams

XRemote Show Commands

This section lists the following commands, with which you monitor XRemote connections:

show xremote

You can use the command show xremote to list XRemote connections and monitor XRemote traffic through the networking hardware. This command provides XRemote parameters applied to the entire system as well as statistics that are pulled for all active XRemote connections. The syntax for this command is as follows:

show xremote

The following is sample output from the show xremote command:

CS> show xremote XRemote server-wide parameters: Font buffersize: 72000 Font retries: 3 Font memory errors: 0 TFTP font load statistics for host 131.108.1.111: Bytes read: 2697239 Files read: 258 Network errors: 4 File errors: 0 LAT font load statistics for service WHEEL, incarnation 5: Bytes read            182401             Files read: 14 Protocol errors:      0                  Insufficient memory: 0 XRemote statistics for tty2: Current clients: 9 Total clients: 17 Requesting client: 5 Current request size: 0 Replying client: 6 Current reply size: 0 XDM state: 10 Next timeout: 172460 Retransmit counter: 0 Local UDP port: 53616 Keepalive dormancy: 180 Session id: 94 Unread input: 0 Unwritten output: 0 Input buffer size: 1024 Output buffer size: 108 Protocol version: 2 Line state: Connected Transmit packets: 50768 Receive packets: 49444 Transmit errors: 0 Receive errors: 37 Retransmissions: 403 Receive out of sequence: 76 Round trip time: 383 Retransmit interval: 766 Transmit window: 7 Receive window: 7 Transmit next: 6 Receive next: 3 Transmit unacked: 6 Receive unacked: 0 Connection 0 - TCP connection from 131.108.1.55 [Display Manager] Client state: CS_ACTIVE Byte order: MSBfirst Unread input: 0 Unwritten output: 0 Input buffer size: 1024 Output buffer size: 1024 Connection 1 - TCP connection from 131.108.1.55 Client state: CS_ACTIVE Byte order: MSBfirst Unread input: 0 Unwritten output: 0 Input buffer size: 1024 Output buffer size: 1024 Connection 2 - TCP connection from 131.108.1.55 Client state: CS_ACTIVE Byte order: MSBfirst Unread input: 0 Unwritten output: 0 Input buffer size: 1024 Output buffer size: 1024  Connection 3 - LAT connection from WHEEL
    Client state:       CS_ACTIVE         Byte order: LSBfirst
    Unread input:       0                 Unwritten output: 0
    Input buffer size:  1024              Output buffer size: 1024

Table 6-17 describes some of the fields shown in the sample output.


Table 6-17: Show XRemote Field Descriptions
Field Description
XRemote server-wide parameters

XRemote parameters that apply to the server product.

Font buffersize

XRemote font buffer size, as specified using the xremote tftp buffersize global configuration command.

Font retries

Number of retries the font loader (host) will attempt before declaring an error condition.

Font memory errors

Number of font memory error conditions that have been declared for the server product.

TFTP font load statistics

XRemote statistics for fonts that have been loaded from a TFTP font server at the IP address shown.

Bytes read

Number of bytes the host read in order to load the fonts.

Files read

Number of files the host read in order to load the fonts.

Network errors

Errors that arise from TFTP network connection failures.

File errors

Bad-format font file errors.

Protocol errors

LAT font loading protocol errors when talking to the font server on VMS.

XRemote statistics for tty

XRemote statistics for the specified line.

Current clients

Number of clients using this line for active Xremote sessions.

Total clients

Number of clients using this line for active Xremote sessions.

Requesting client

Number of clients requesting Xremote service.

Retransmit counter

Number of times that an Xremote connection request was retransmitted.

Local UDP port

Number assigned to the local UDP port.

Keepalive dormancy

Amount of time between keepalive messages.

Client state

XRemote state.

Byte order

Byte ordering used between the X Server (the X Terminal) and the X Client (the UNIX host).

LSBfirst

Little Endian byte ordering.

MSBfirst

Big Endian byte ordering.

show xremote line

You can use the command show xremote line with a line number to list XRemote connections and monitor XRemote traffic for specific lines on a server product. The syntax for this command is as follows:

show xremote line number

Syntax Description

number

Decimal value representing virtual terminal lines on a server product.

The following is sample output from a show xremote line command when XRemote is enabled on a communication or access server and XRemote sessions are active. Only information about an individual terminal line is provided. Table 6-17 describes the fields in the display:

CS# show xremote line 3 Xremote statistics for tty3: Current clients: 11 Total clients: 19 Requesting client: 10 Current request size: 0 Replying client: 10 Current reply size: 0 XDM state: 10 Next timeout: 173304 Retransmit counter: 0 Local UDP port: 28384 Keepalive dormancy: 180 Session id: 29 Unread input: 0 Unwritten output: 0 Input buffer size: 1024 Output buffer size: 108 Protocol version: 2 Line state: Connected Transmit packets: 28875 Receive packets: 18644 Transmit errors: 0 Receive errors: 13 Retransmissions: 53 Receive out of sequence: 41 Round trip time: 384 Retransmit interval: 768 Transmit window: 7 Receive window: 7 Transmit next: 2 Receive next: 7 Transmit unacked: 2 Receive unacked: 0 Connection 0 - TCP connection from 131.108.1.27 [Display Manager] Client state: CS_ACTIVE Byte order: MSBfirst Unread input: 0 Unwritten output: 0 Input buffer size: 1024 Output buffer size: 1024 Connection 1 - TCP connection from 131.108.1.27 Client state: CS_ACTIVE Byte order: MSBfirst Unread input: 0 Unwritten output: 0 Input buffer size: 1024 Output buffer size: 1024 Connection 2 - TCP connection from 131.108.1.27 Client state: CS_ACTIVE Byte order: MSBfirst Unread input: 0 Unwritten output: 0 Input buffer size: 1024 Output buffer size: 1024

Protocol Translation Show Command

This section describes the show x25 pad command.

show x25 pad

Use the show x25 pad command to display information about current open connections. This information includes packet transmissions, X.3 parameter settings, and information about the current status of virtual circuits. The syntax for this command is as follows:

show x25 pad

Sample Display

The following is sample output from the show x25 pad command:

sloth# show x25 pad tty2, Incoming PAD connection Total input: 61, control 6, bytes 129. Queued: 0 of 7 (0 bytes). Total output: 65, control 6, bytes 696. Flags: 1, State: 3, Last error: 1 ParamsIn: 1:1, 2:0, 3:2, 4:1, 5:1, 6:0, 7:21, 8:0, 9:0, 10:0, 11:14, 12:0, 13:0, 14:0, 15:1, 16:127, 17:21, 18:18, 19:0, 20:0, 21:0, 22:0, ParamsOut: 1:1, 2:1, 3:2, 4:1, 5:0, 6:0, 7:4, 8:0, 9:0, 10:0, 11:14, 12:0, 13:0, 14:0, 15:0, 16:127, 17:21, 18:18, 19:0, 20:0, 21:0, 22:0, LCI: 1, State: D1, Interface: Serial0 Started 0:11:10, last input 0:00:16, output 0:00:16 Connected to 313700540651 Window size input: 7, output: 7 Packet size input: 512, output: 512 PS: 1 PR: 5 ACK: 5 Remote PR: 1 RCNT: 0 RNR: FALSE Retransmits: 0 Timer (secs): 0 Reassembly (bytes): 0 Held Fragments/Packets: 0/0 Bytes 696/129 Packets 65/61 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0

Table 6-18 describes significant fields shown in the output in the display.


Table 6-18: Show X.25 Pad Field Descriptions
Field Description

Total input/output

Number of packets received or sent for the connection.

Control

Number of packets with Qbit set (X.29 control packets).

Bytes

Number of bytes in each direction.

Queued

Number of unread packets waiting for the connection.

Waiting to send

Local data packet bit not sent (part of a line).

Flags, state, last error

Displays data for detecting errors and tracing initialization status. Only useful to your technical support personnel.

Params In

Parameters read from the PAD at the start of the connection.

ParamsOut

Active X.3 parameters.

The line beginning LCI:

Status of the X.25 virtual circuit associated with the PAD connection, and is the same display as for the show x25 vc command.

Managing Connections

The following sections describe connection management activities that apply to all supported transmission protocols:

Assign a Logical Name to a Connection

You can assign a logical name to a connection. This can be useful for keeping track of multiple connections. To name a connection, issue the following command:

name-connection

You are prompted for the connection number and name to assign. The where command displays a list of the assigned logical connection names.

Escape a Connection

Escape a connection when you want to switch to another connection. Enter the escape sequence (Ctrl-^ X by default), to return to the system command prompt.

To make a new connection or switch between connections, refer to the "Terminal Service Connections" chapter earlier in this publication.

Set X.3 PAD Parameters

You can use both the resume command and the x3 command to set X.3 PAD parameters. These parameters are numbered from 1 through 18. Table 6-19 describes these parameters and their values.

The resume command has the following syntax when setting X.3 parameters:

resume [connection] [/set parameter:value]

The x3 command has the following syntax:

x3 parameter:value

Syntax Description

connection

(Optional) Name or number of the connection; the default is the most recent connection.

/set parameter:value

(Optional) Sets PAD parameters for the protocol translator.

parameter:value

Sets the PAD parameters.


Table 6-19:
PAD Parameters
Parameter Action Value Description

1

Escape from Data Transfer

Not supported.

2

Local Echo Mode

0

1

No local echo (incoming PAD connection default).

Local echo on (outgoing connection default).

3

Data Forward Character

0

1

2

4

8

16

32

64

None—full packet.

Forward packet on receipt of an alphanumeric character.

Forward packet on receipt of a RETURN (outgoing connection default).

Forward packet on receipt of ESCAPE, BEL, ENQ, or ACK.

Forward packet on receipt of DEL, CAN, or DC2.

Forward packet on receipt of ETX or EOT.

Forward packet on receipt of HT, LT, VT, or FF.

All other characters in the ASCII chart.

4

Idle Timer

0

1-255

No timer.

Delay value in twentieths of a second (default for both connection types is 1).

5

Device Control

Not supported.

6

PAD Service Signals

Not supported.

7

Receipt of BREAK

0

1

2

4

8

16

21

Ignore the BREAK signal.

Transmit an INTERRUPT packet to notify the remote host or another PAD that the BREAK signal was generated.

Transmit a RESET packet to reset the virtual circuit.

Transmit an X.29 break indication to the remote host, or to a PAD (outgoing connection default).

Escape from data transfer mode.

Discard output to the terminal by setting parameter 8 to a value of 1.

Combination of values 1, 4 and 16 (incoming connection default).

8

Discard Output

0

1

Normal data delivery to the terminal (outgoing connection default).

Discard all output to the terminal; set by parameter 7.

9

Return Padding

Not supported.

10

Line Folding

Not supported.

11

Baud Rate

10

5

9

0

1

6

8

2

4

3

7

11

12

13

14

15

16

17

18

50 baud

75 baud

100 baud

110 baud

134.5 baud

150 baud

200 baud

300 baud

6001 baud

1200 baud

1800 baud

75/12002 baud

2400 baud

4800 baud

9600 baud

19200 baud

48000 baud

56000 baud

64000 baud

12

Input Flow Control

Not supported.

13

Line Feed Insertion

0

1

2

4

Do not insert (outgoing connection default).

Insert after transmitting RETURN to the terminal.

Insert after echoing RETURN to the terminal.

Insert after echoing RETURN to the remote host.

14

Line Feed Padding

Not supported.

15

Local Editing

0

1

Disables editing capabilities.

Enables editing capabilities.

16

Character Delete

0-127

Select one ASCII character. Default is ASCII 127 (Del).

17

Line Delete

0-127

Select one ASCII character. Default is ASCII 21
(Ctrl-U).

18

Line Display

0-127

Select one ASCII character. Default is ASCII 18
(Ctrl-R).

1600 is the beginning of values that are PAD-type dependent.
275 is from PAD; 1200 is to PAD.
Default Values

For outgoing connections, the X.3 parameters default to the following:

2:1, 3:2, 4:1, 7:4, 16:127, 17:21, 18:19

All other parameters default to zero, but can be changed using the /set switch with either the resume command or the x3 command.

For incoming PAD connections, the software sends an X.29 SET PARAMETER packet to set only the following parameters:

2:0, 4:1, 7:21, 15:0

For a complete description of the X.3 PAD parameters, refer to the configuration guide or command reference manual for your server product.

Example

The following example illustrates how to reset the outgoing connection default for local echo mode on a router.

router> resume 3 /set 2:1

The /set switch sets the X.3 parameters defined by parameter number and value, separated by a colon.

Change a Login Name

You can change your login username if you must match outgoing access list requirements or other login prompt requirements. To change a login username, enter the login user EXEC command at the system prompt.

When you enter this command, the system prompts you for a username and password. Enter the new username and the original password. If the username does not match, but the password does, the session changes to the new username with which the login command attempt was made.

If no username and password prompts appear, your administrator did not specify that a username and password be required at login time. If both the username and password are entered correctly, the session becomes associated with the specified username.

When you access a system with TACACS security, you can enter your login name or specify a TACACS server by using the following command when the "Username:" prompt appears:

user @tacacs-server

The server product must be one of the server products defined in a server product configuration. For more information, refer to the "Specify a TACACS Host" section later in this chapter, or refer to the tacacs-server host command in the publications Access and Communication Servers Command Reference or Protocol Translation Configuration Guide and Command Reference.

If you do not specify a host, the server product will try each of the TACACS servers in the list until it receives a response.

If you do specify a host and that host does not respond, no other TACACS server will be queried. The server product will either deny access or behave according to the action specified by the tacacs-server last-resort command, if there is one configured.

If you specified a TACACS server host with the user @tacacs-server argument, the TACACS server specified will be used for all subsequent authentication or notification queries, with the possible exception of SLIP address queries.

Example

The following example shows how login usernames and passwords can be changed. In this case, a user currently logged on under the username "webster" attempts to change that login name to "sloan." After entering the login command, the user enters the new username, but enters an incorrect password. Because the password does not match the original password, the system rejects the attempt to change the username.

CS> login Username: sloan Password: % Access denied Still logged in as "webster"

Next, the user attempts the login change again, with the user name "sloan," but enters the correct (original) password. This time the password matches the current login information, the login username is changed to "sloan," and the user is allowed access to the EXEC at the user-level.

CS> login Username: sloan Password: cs>

Lock Access to a Terminal

You can prevent access to your session while keeping your connection open by setting up a temporary password. To lock access to the terminal, follow this procedure:


Step 1   Issue the lock command.

When you issue this command, the system prompts you for a password.

Step 2   Enter a password, which can be any arbitrary string.

The screen clears and displays the message "Locked."

Step 3   To regain access to your sessions, re-enter the password.

The server product honors session time-outs on a locked line. You must clear the line to remove this feature. The system administrator must set the line up to allow use of the temporary locking feature.

Specify a TACACS Host

You can specify a TACACS host when you dial in or use the login command. Only the specified host will be searched for user authentication information.

To specify the name of a TACACS host at login, issue the following command:

user @hostname

Syntax Description

@hostname

Address or logical name of the TACACS host.

Example

In the following example, user Imran specifies the TACACS host host1 to authenticate the password.

george> login Username: imran@host1 Translating "HOST1"...domain server (131.108.1.111) [OK]

Send Messages to Other Terminals

You can send messages to one or all terminal lines. A common reason for doing this is to inform users of an impending shutdown. To send a message to other terminals, issue the following command:

send {line-number | *}

Syntax Description

line-number

Line number to which the message will be sent.

*

Message will be sent to all lines.

The system prompts for the message, which can be up to 500 characters long. Enter Ctrl-Z to end the message. Enter Ctrl-C to abort the command.

Exit a Session

You can issue any of the following commands to terminate an active terminal session:

exit

quit

logout

Log Out of a Server

To log out of a server product, press Ctrl-] at the server prompt.

When the telnet> prompt appears, type quit.

Disconnect a Line

To disconnect a line, issue the following command:

disconnect [connection]

Syntax Description

connection

(Optional) Line to be disconnected.

Do not disconnect a line to end a session. Instead, log off the host, thus allowing the server product to clear the connection. Then end the session. If you cannot log out of an active session, disconnect the line.


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Posted: Mon Oct 21 12:34:28 PDT 2002
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