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Table Of Contents
E Through M Commands for Cisco DSLAMs with NI-2
ima differential-delay-maximum
ip dhcp relay information option
E Through M Commands for Cisco DSLAMs with NI-2
This chapter documents commands that you use to configure Cisco DSLAMs with NI-2. Commands in this chapter are listed alphabetically. For information on how to configure DSL features, refer to the Configuration Guide for Cisco DSLAMs with NI-2.
Note
Commands that are identical to those documented in the Cisco IOS Configuration Fundamentals Command Reference and the ATM and Layer 3 Switch Router Command Reference have been removed from this chapter.
This chapter discusses the following commands:
ima differential-delay-maximum
ip dhcp relay information option
encapsulation
To set the encapsulation method that the interface uses , use the encapsulation interface configuration command.
encapsulation encapsulation-type
Syntax Description
encapsulation-type
Encapsulation type. See Table 4-1 for a list of supported encapsulation types.
Defaults
The default depends on the type of interface.
Command Modes
Interface configuration
Command History
Usage Guidelines
For you to use SLIP or PPP, the router or access server must be configured with an IP routing protocol or with the ip host-routing command. This configuration is done automatically if you are using old-style SLIP address commands. However, you must configure manually if you configure SLIP or PPP with the interface async command.
The following example enables aal5snap encapsulation on atm interface 1/1:
DSLAM#conf tDSLAM(config)#interface atm0/1DSLAM(config-if)#atm pvc 0 100 interface atm 0/0 0 100 encap aal5snapRelated Commands
ppp authentication
Enables Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) and enables an AAA authentication method on an interface.
exit-address-family
To exit from the address-family submode, use the exit-address-family address-family submode command.
exit-address-family
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
Address-family submode
Command History
Usage Guidelines
You can abbreviate this command to exit.
Examples
The following example shows how to exit the address-family command mode:
DSLAM# configure terminalDSLAM(config)# router bgp 100DSLAM(config-router)# address-family ipv4 unicast vrf vrf2DSLAM(config-router-af)# exit-address-familyRelated Commands
address-family
Enters the address-family submode that you use to configure routing protocols.
framing
To select the frame type for the data link, use the framing interface configuration command. To restore the default values, use the no form of this command.
framing framingmode
Syntax Description
framingmode
Specify framingmode as follows:
•
•
•
•
Defaults
For E1: pcm30
For E3: g832adm
For T1: esf
For DS3: cbitadm
Command Modes
Interface configuration
Command History
Usage Guidelines
In the E1 environment, the framing command allows selection of the E1 frame type to CRC4 enabled framing mode (crc4) or CRC4 disabled framing mode (pcm30).
In the E3 environment, the framing command allows the selection of the E3 frame type to g751 ADM, g751 PLCP, or g832 ADM.
In the T1 environment, the framing command allows selection of the T1 frame type to extended super frame (esf) or super frame (sf).
In the DS3 environment, the framing command allows the selection of the DS3 frame type to C-Bit ADM, C-Bit PLCP, M23 ADM, or M23 PLCP.
Note
Examples
The following example shows how to select m23plcp as the frame type:
DSLAM(config)# interface atm 0/1DSLAM(config-if)# framing m23plcpRelated Commands
hardware-address
To specify the hardware address of a Dynamic Host Configuration Protocol (DHCP) client, use the hardware-address DHCP pool configuration command. This command is valid for manual bindings only. Use the no form of this command to remove the hardware address.
hardware-address hardware-address type
no hardware-address
Syntax Description
Defaults
Ethernet is the default type if if you do not specify one.
Command Modes
DHCP pool configuration
Command History
Examples
The following example specifies b708.1388.f166 as the MAC address of the client:
DSLAM(config)#ip dhcp pool 1DSLAM(dhcp-config)#hardware-address b708.1388.f166Related Commands
host
To specify the IP address and network mask for a manual binding to a Dynamic Host Configuration Protocol (DHCP) client, use the host DHCP pool configuration command. Use the no form of this command to remove the client IP address.
host address [mask | /prefix-length]
no host
Syntax Description
Defaults
No default behavior or values.
Command Modes
DHCP pool configuration
Command History
Usage Guidelines
If you do not specify the mask and prefix length, DHCP examines its address pools. If the software fails to find a mask in the pool database, it uses the Class A, B, or C natural mask. This command is valid for manual bindings only.
Examples
The following example specifies 10.12.1.99 as the client IP address and 255.255.248.0 as the subnet mask:
DSLAM#conf tDSLAM(config)#ip dhcp pool testDSLAM(dhcp-config)#host 10.12.1.99 255.255.248.0Related Commands
ima active-links-minimum
To configure the minimum number of active links required for an IMA group to function, use the ima active-links-minimum interface configuration command. To restore the default value, use the no form of this command.
ima active-links-minimum number
no ima active-links-minimum
Syntax Description
Defaults
No minimum links is the default (no ima active-links-minimum or ima active-links-minimum 1).
Command Modes
Interface configuration
Command History
Usage Guidelines
This command sets the minimum number of links that must be in the active state before the IMA group interface becomes active. If at any time the number of active links is less than this value, the IMA group interface will no longer be active.
Examples
The following example uses the ima active-links-minimum command to configure the minimum number of active links that must be active for the IMA group to function correctly:
DSLAM(config)#interface atm 0/ima0DSLAM(config-if)# ima active-links-minimum 2Related Commands
ima clock-mode
To set the transmit clock mode for an ATM IMA group, use the ima clock-mode interface configuration command. To restore the default value, use the no form of this command.
ima clock-mode {common {2-9} | independent}
no ima clock-mode
Syntax Description
Defaults
By default, the first link added to the group is used as the common clock source (ima clock-mode common).
Command Modes
Interface configuration
Command History
Usage Guidelines
This command controls the clock for the IMA group as a whole. When you set the independent keyword, the clock source interface configuration command is used under each interface to determine clocking individually. When you set the common keyword, the clock source interface configuration command for the common link determines clocking for all the links in the group.
Note
Examples
The following example uses the ima clock-mode command to configure the IMA group clocking mode as independent:
DSLAM(config)# interface atm 0/ima0DSLAM(config-if)# ima clock-mode independentRelated Commands
ima differential-delay-maximum
To specify a maximum differential timing delay among the links in an IMA group, use the ima differential-delay-maximum interface configuration command. If a link delay exceeds the specified maximum, the link drops; otherwise, the IMA feature, while multiplexing and demultiplexing, adjusts for differences in delays to align all links in a group. The no form of the command restores the default setting.
ima differential-delay-maximum {msecs}
no ima differential-delay-maximum
Syntax Descriptionn
msecs
Maximum differential delay in milliseconds as follows:
•
•
Defaults
The default is 25 milliseconds.
Command Modes
Interface configuration
Command History
Usage Guidelines
The transmitter on the T1/E1 IMA port adapter must align the transmission of IMA frames on all interfaces that are members of the IMA group. This alignment allows the receiver to adjust for differential link delays among the interfaces that are members of the IMA group. Based on this required behavior, the receiver can detect the differential delays by measuring the arrival times of the IMA frames on each link.
At the transmitting end, the cells transmit continuously. If no ATM layer cells need to transmit between IMA control protocol (ICP) cells with an IMA frame, then the transmit IMA sends filler cells to maintain a continuous stream of cells at the physical layer.
Examples
The following example configures the maximum allowable differential delay to 55 milliseconds for all interfaces assigned to the IMA group:
DSLAM(config)# interface atm 0/ima0DSLAM(config-if)# ima differential-delay-maximum 55Related Commands
ima frame-length
To set the IMA frame length in cells per frame, use the ima frame-length interface configuration command.
ima frame-length {32 | 64 | 128 | 256}
no ima frame-length
Syntax Description
32
Configure IMA frame length to 32 cells.
64
Configure IMA frame length to 64 cells.
128
Configure IMA frame length to 128 cells (default).
256
Configure IMA frame length to 256 cells.
Defaults
The default is 128 cells.
Command Modes
Interface configuration
Command History
Usage Guidelines
An IMA group uses the frame length parameter to set the insertion of the IMA control protocol (ICP) cells at the beginning of frames in the transmit direction. Normally, one ICP cell is sent per IMA frame. The larger the IMA frame, the less overhead there is at the expense of a decrease in allowable timing differences between the lengths.
Examples
The following example uses the ima frame-length command to configure the frame length that is transmitted as 64 cells for the IMA group:
DSLAM(config)# interface atm 0/ima0DSLAM(config-if)# ima frame-length 64Related Commands
show ima interface
Displays information about all IMA groups and the links in those groups.
ima-group
To assign a T1/E1 link to an IMA group, use the ima-group interface configuration command. The ima-group interface configuration command applies only to atm 0/2 through atm 0/9 (see Table 2-3 on page 2-26).To remove a link from an IMA group, use the no form of this command.
ima-group number
no ima-group
Syntax Description
Defaults
The links do not belong to any IMA group by default.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use the ima-group interface command to configure a T1/E1 port adapter interface as part of an IMA group. IMA allows you to aggregate multiple low-speed links into one larger virtual trunk or IMA group. This IMA group appears to your ATM switch router as one logical pipe. It also provides modular bandwidth for user access to ATM networks for connections between ATM network elements that are at rates between traditional multiplexing levels, such as between T1/E1, and DS3/E3.
IMA requires inverse multiplexing and demultiplexing of ATM cells in a cyclical fashion among links that are grouped to form a higher-bandwidth logical group with a rate of approximately the sum of the link rates. This grouping is called an IMA group.
Examples
The following example uses the ima-group command to assign link 0 to IMA group 0:
DSLAM(config)# interface atm 0/2DSLAM(config-if)# ima-group 0Related Commands
ima test
To configure an IMA group test pattern transmitted in the ICP cells, use the ima test interface configuration command. To restore the default value, use the no form of this command.
ima test [link link-value] [pattern pattern-value]
no ima test
Syntax Description
Defaults
The link-value is 2.
The pattern-value is 166.
The default is no ima test.
Command Modes
Interface configuration
Command History
Usage Guidelines
The test pattern procedure verifies the connectivity of a link within an IMA group. The procedure uses a test pattern that it sends over one link to verify the connectivity to the other links in the IMA group. Ensure that the test pattern loops over all the other links in the group at the far end of the connection. The system performs all of the IMA test pattern procedures over the ICP cells that are exchanged between both ends of the IMA virtual links. After you configure the test on the IMA group, the test continues explicitly until you issue the no form of the command.
Examples
The following example uses the ima test command to configure the test pattern of 100 to transmit over ATM interface 0 of IMA group 0:
DSLAM(config)# interface atm 0/ima0DSLAM(config-if)# ima test link 2 pattern 100Related Commands
show ima interface
Displays information about all IMA groups and the links in those groups.
ima version
To set the operating mode of an IMA group, use the ima version interface configuration command. To restore the default value, use the no form of this command.
ima version {1.0 | 1.1}
no ima version
Syntax Description
Defaults
The default is version 1.0 mode.
Command Modes
Interface configuration
Command History
Examples
The following example uses the ima version command to set the IMA version to 1.1:
DSLAM(config)# interface atm 0/ima0DSLAM(config-if)# ima version 1.1Related Commands
import map
To configure an import route map for a VPN routing/forwarding instance (VRF), use the import map VRF submode command.
import map route-map
Syntax Description
Defaults
There is no default. A VRF has no import route map unless you configure one by using the import map command.
Command Modes
VRF submode
Command History
Usage Guidelines
Use an import route map when you require control over the routes that you import into a VRF that is finer than the control provided by the import and export extended communities that are configured for the importing and exporting VRF.
The import map command associates a route map with the specified VRF. You can filter routes that are eligible for import into a VRF, based on the route target extended community attributes of the route, through the use of a route map.
Examples
The following example shows how to configure an import route map for a VRF:
DSLAM(config)# ip vrf vrf_blueDSLAM(config-vrf)# import map blue_import_mapRelated Commands
ip cef traffic-statistics
To change the time interval that controls when Next Hop Resolution Protocol (NHRP) will set up or tear down a switched virtual circuit (SVC), use the ip cef traffic-statistics global configuration command. To restore the default values, use the no form of this command.
ip cef traffic-statistics [load-interval seconds] [update-rate seconds]
no ip cef traffic-statistics
Syntax Description
Defaults
load-interval: 30 seconds
update-rate: 10 seconds
Command Modes
Global configuration
Command History
Usage Guidelines
To change the interval, use the load-interval seconds argument of the ip cef traffic-statistics command.
Examples
In the following example, the triggering and teardown thresholds are calculated based on an average over 120 seconds:
DSLAM(config)# ip cef traffic-statistics load-interval 120Related Commands
ip nhrp trigger-svc
Configures when NHRP will set up and tear down an SVC based on aggregate traffic rates.
ip classless
At times the router might receive packets destined for a subnet of a network that has no network default route. To have the Cisco IOS software forward such packets to the best supernet route possible, use the ip classless global configuration command. To disable this feature, use the no form of this command.
ip classless
no ip classless
Syntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Global configuration
Command History
Usage Guidelines
This command allows the software to forward packets that are destined for unrecognized subnets of directly connected networks. The packets are forwarded to the best supernet route.
When this feature is disabled, the software discards the packets for a subnet that numerically falls within its subnetwork addressing scheme. If there is no such subnet number in the routing table, there is no network default route.
Examples
The following example prevents the software from forwarding packets that are destined for an unrecognized subnet to the best supernet possible:
DSLAM(config)# no ip classlessRelated Commands
None.
ip default-gateway
To define a default gateway (router) when IP routing is disabled, use the ip default-gateway global configuration command. To disable this function, use the no form of this command.
ip default-gateway ip-address
no ip default-gateway ip-address
Syntax Description
Defaults
Disabled
Command Modes
Global configuration
Command History
Usage Guidelines
The Cisco IOS software sends any packets that need the assistance of a gateway to the address you specify. If another gateway has a better route to the requested host, the default gateway sends an ICMP Redirect message back. The ICMP Redirect message indicates which local router the Cisco IOS software should use.
Examples
The following example defines the router on IP address 192.168.7.18 as the default router:
DSLAM(config)# ip default-gateway 192.168.7.18Related Commands
None.
ip dhcp conflict logging
To enable conflict logging on a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server, use the ip dhcp conflict logging global configuration command. Use the no form of this command to disable conflict logging.
ip dhcp conflict logging
no ip dhcp conflict logging
Syntax Description
This command has no arguments or keywords.
Defaults
Conflict logging is enabled.
Command Modes
Global configuration
Command History
Usage Guidelines
We recommend that you use a DHCP server database agent to store automatic bindings. If you decide not to use a DHCP server database agent to store automatic bindings, use the no ip dhcp conflict logging command to disable the recording of address conflicts. By default, the Cisco IOS DHCP server records DHCP address conflicts in a log file.
Examples
The following example disables the recording of DHCP address conflicts:
DSLAM(config)#no ip dhcp conflict loggingRelated Commands
ip dhcp database
You can configure a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server to save automatic bindings on a remote host called a database agent. To configure a DHCP server database agent and database agent parameters, use the ip dhcp database global configuration command. Use the no form of this command to remove the database agent.
ip dhcp database url [timeout seconds | write-delay seconds]
no ip dhcp database url
Syntax Description
Defaults
DHCP waits 300 seconds for both a write delay and a timeout.
Command Modes
Global configuration
Command History
Usage Guidelines
The administrator can configure multiple database agents. Transfer bindings by using the File Transfer Protocol (FTP), Trivial File Transport Protocol (TFTP), or Remote Copy Protocol (RCP).
Examples
The following example specifies the DHCP database transfer timeout value at 80 seconds:
DSLAM(config)#ip dhcp database ftp://user:password@172.16.1.1/router-dhcp timeout 80The following example specifies the DHCP database update delay value at 100 seconds:
DSLAM(config)#ip dhcp database tftp://172.16.1.1/router-dhcp write-delay 100Related Commands
show ip dhcp database
Displays Cisco IOS DHCP server database agent information.
ip dhcp excluded-address
To specify IP addresses that a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server should not assign to DHCP clients, use the ip dhcp excluded-address global configuration command. Use the no form of this command to remove the excluded IP addresses.
ip dhcp excluded-address low-address [high-address]
no ip dhcp excluded-address low-address [high-address]
Syntax Description
low-address
The excluded IP address, or first IP address in an excluded address range.
high-address
(Optional) The last IP address in the excluded address range.
Defaults
All IP pool addresses are assignable.
Command Modes
Global configuration
Command History
Usage Guidelines
The DHCP server assumes that it can assign all pool addresses to clients. Use this command to exclude a single IP address or a range of IP addresses.
Examples
The following example configures an excluded IP address range from 172.16.1.100 through 172.16.1.199:
DSLAM(config)#ip dhcp excluded-address 172.16.1.100 172.16.1.199Related Commands
ip dhcp ping packets
To specify the number of packets that a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server sends to a pool address as part of a ping operation, use the ip dhcp ping packets global configuration command. Use the no form of this command to prevent the server from pinging pool addresses.
ip dhcp ping packets count
no ip dhcp ping packets
Syntax Description
count
Indicates the number of ping packets that the DHCP server sends before the address is assigned to a requesting client. The default value is two packets.
Defaults
Two packets
Command Modes
Global configuration
Command History
Usage Guidelines
The DHCP server pings a pool address before it assigns the address to a requesting client. If the ping is unanswered, the DHCP server assumes (with a high degree of probability) that the address is not in use and assigns the address to the requesting client.
Examples
The following example specifies five ping attempts by the DHCP server before the server ceases any further ping attempts:
DSLAM(config)#ip dhcp ping packets 5Related Commands
ip dhcp ping timeout
To specify how long a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server waits for a ping reply from an address pool, use the ip dhcp ping timeout global configuration command. Use the no form of this command to restore the default number of milliseconds (500) for the timeout.
ip dhcp ping timeout milliseconds
no ip dhcp ping timeout
Syntax Description
Defaults
500 milliseconds
Command Modes
Global configuration
Command History
Usage Guidelines
This command specifies how long to wait for a ping reply in milliseconds.
Examples
The following example specifies that the DHCP server will wait 800 milliseconds for a ping reply before considering the ping a failure:
DSLAM(config)#ip dhcp ping timeout 800Related Commands
ip dhcp pool
To configure a Dynamic Host Configuration Protocol (DHCP) address pool on a Cisco IOS DHCP server and enter DHCP pool configuration mode, use the ip dhcp pool global configuration command. Use the no form of this command to remove the address pool.
ip dhcp pool name
no ip dhcp pool name
Syntax Description
Defaults
DHCP address pools are not configured.
Command Modes
Global configuration
Command History
Usage Guidelines
During execution, the configuration mode changes to DHCP pool configuration mode, which is identified by the (config-dhcp)# prompt. In this mode, the administrator can configure pool parameters, such as the IP subnet number and default router list.
Examples
The following example configures pool1 as the DHCP address pool:
DSLAM(config)#ip dhcp pool pool1Related Commands
This command is used by cable modem termination systems. By default, DHCP checks relay information. Invalid messages are dropped.
ip dhcp relay information option
To configure a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server to insert the DHCP relay agent information option in forwarded BOOTREQUEST messages, use the ip dhcp relay information option global configuration command. Use the no form of this command to disable the insertion of relay information to forwarded BOOTREQUEST messages.
ip dhcp relay information option
no ip dhcp relay information option
Syntax Description
This command has no arguments or keywords.
Defaults
The DHCP server does not insert relay information.
Command Modes
Global configuration
Command History
Usage Guidelines
This command is used by cable modem termination systems. By default, DHCP does not insert relay information.
Examples
The following example configures a DHCP server to insert the DHCP relay agent information option in forwarded BOOTREQUEST messages:
DSLAM(config)#ip dhcp relay information optionRelated Commands
ip helper-address
To have the Cisco IOS software forward User Datagram Protocol (UDP) broadcasts, including BOOTP, that are received on an interface, use the ip helper-address interface configuration command. To disable the forwarding of broadcast packets to specific addresses, use the no form of this command.
ip helper-address address
no ip helper-address address
Syntax Description
address
Destination broadcast or host address to be used when forwarding UDP broadcasts. There can be more than one helper address per interface.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
One common application that requires helper addresses is Dynamic Host Configuration Protocol (DHCP), which is defined in RFC 1531. DHCP protocol information is carried inside of BOOTP packets. To enable BOOTP broadcast forwarding for a set of clients, configure a helper address on the router interface that is closest to the client. The helper address should specify the address of the DHCP server. If you have multiple servers, you can configure one helper address for each server. Because BOOTP packets are forwarded by default, DHCP information can now be forwarded by the router. The DHCP server then receives broadcasts from the DHCP clients.
Note
Examples
In the following example, DHCP option 82 support is enabled on the DHCP relay agent using the ip dhcp relay agent information option command. The rbe nasip command configures the DSLAM to forward the IP address for Loopback0 to the DHCP server.
DSLAM(config)# ip dhcp relay information optionDSLAM(config)# ip dhcp-server 10.0.0.202DSLAM(config)# rbe nasip Loopback1DSLAM(config)# interface Loopback1DSLAM(config-if)# ip address 18.52.86.120 255.255.255.255DSLAM(config-if)# interface Ethernet0/0DSLAM(config-if)# ip address 10.0.0.40 255.0.0.0DSLAM(config-if)# interface atm1/1DSLAM(config-if)# ip address 11.0.0.1 255.0.0.0DSLAM(config-if)# ip helper-address 10.0.0.202DSLAM(config-if)# atm route-bridged ipDSLAM(config-if)# no atm ilmi-keepaliveDSLAM(config-if)# pvc 1/1DSLAM(config-if)# encapsulation aal5snapDSLAM(config-if)# interface ATM1/2DSLAM(config-if)# ip address 12.0.0.1 255.0.0.0DSLAM(config-if)# ip helper-address 10.0.0.202DSLAM(config-if)# atm route-bridged ipDSLAM(config-if)# no atm ilmi-keepaliveDSLAM(config-if)# pvc 1/1DSLAM(config-if)# encapsulation aal5snapRelated Commands
None.
ip local pool
To configure a local IP address pool group, use the ip local pool configuration command with the group name. To disband the group, use the no form of this command.
ip local pool pool-name start-IP [end-IP] [group group-name] [cache-size size]
no ip local pool
Syntax Description
Defaults
Any pool that you create without the optional group keyword is a member of the base system group.
Command Modes
Global configuration
Command History
Usage Guidelines
All pool names must be unique. Use of a duplicate name extends that pool.
If you specify a (named) pool within a pool group, the software allows overlapping IP addresses to exist with pools in other groups and with pools in the "base system" pool. The software does not allow the overlapping IP address to exist among pools within a group. Otherwise, pool processing is not altered by pool membership in a group. That is, you can use these (named) pools anywhere that pools can be used in the current implementation.
Addresses return to the pool from which they were allocated.
Examples
DSLAM(config)#ip local pool p1_g1 10.1.1.1 10.1.1.50 group grp1DSLAM(config)#ip local pool p2_g1 10.1.1.100 10.1.1.110 group grp1DSLAM(config)#ip local pool p1_g2 10.1.1.1 10.1.1.40 group grp2DSLAM(config)#ip local pool lp1 10.1.1.1 10.1.1.10DSLAM(config)#ip local pool p3_g1 10.1.2.1 10.1.2.30 group grp1DSLAM(config)#ip local pool p2_g2 10.1.1.50 10.1.1.70 group grp2DSLAM(config)#ip local pool lp2 10.1.2.1 10.1.2.10Related Commands
debug ip peer
This command contains additional output when pool groups are defined.
ip route vrf
To establish static routes for a VRF, use the ip route vrf global configuration command. To disable static routes, use the no form of this command.
ip route vrf vrf-name prefix mask {[next-hop-address] | [interface {interface-number}]} [global] [distance] [permanent] [tag tag]
no ip route vrf vrf-name prefix mask {[next-hop-address] | [interface {interface-number}]} [global] [distance] [permanent] [tag tag]
Syntax Description
Defaults
No default behavior or values.
Command Modes
Global configuration
Command History
Usage Guidelines
Use a static route if the Cisco IOS software cannot dynamically build a route to the destination.
If you specify an administrative distance when you set up a route, you are flagging a static route that can be overridden by dynamic information. For example, IGRP-derived routes are configured with a default administrative distance of 100. To set a static route to be overridden by an IGRP dynamic route, specify an administrative distance greater than 100. Static routes each have a default administrative distance of 1.
Static routes that point to an interface are advertised through RIP, IGRP, and other dynamic routing protocols, regardless of whether the routes are redistributed into those routing protocols. That is, static routes configured by specifying an interface lose their static nature when installed into the routing table.
However, if you define a static route to an interface that is not defined in a network command, no dynamic routing protocols advertise the route unless you specify a redistribute static command for these protocols.
Examples
The following command shows how to reroute packets addressed to network 137.23.0.0 in VRF vpn3 to router 131.108.6.6:
DSLAM(config)# ip route vrf vpn3 137.23.0.0 255.255.0.0 131.108.6.6Related Commands
ip routing
To enable IP routing, use the ip routing global configuration command. To disable IP routing, use the no form of this command.
ip routing
no ip routing
Syntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Global configuration
Command History
Examples
The following example enables IP routing:
DSLAM(config)#ip routingRelated Commands
None.
ip subnet-zero
To enable the use of subnet zero for interface addresses and routing updates, use the ip subnet-zero global configuration command. To restore the default, use the no form of this command.
ip subnet-zero
no ip subnet-zero
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Global configuration
Command History
Usage Guidelines
The ip subnet-zero command enables you to configure and route to subnet-zero subnets.
We discourage subnetting with a subnet address of zero because of the confusion inherent when you have a network and a subnet with indistinguishable addresses.
Examples
The following example enables subnet-zero:
DSLAM(config)#ip subnet-zeroRelated Commands
None.
ip unnumbered
To enable IP processing on an ATM interface without assigning an explicit IP address to the interface, use the ip unnumbered interface configuration command. To disable the IP processing on the interface, use the no form of this command.
ip unnumbered type number
Syntax Description
type number
Type and number of another interface on which the router has an assigned IP address. This number cannot be another unnumbered interface.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Whenever the unnumbered interface generates a packet (for example, for a routing update), it uses the address of the specified interface as the source address of the IP packet. The unnumbered interface also uses the address of the specified interface to determine which routing processes are sending updates over the unnumbered interface. Restrictions include the following:
•
•
•
•
The interface that you specify by the type and number arguments must be enabled (listed as "up" in the show interfaces command display).
If you are configuring IS-IS across a serial line, you should configure the serial interfaces as unnumbered. Doing so allows you to conform with RFC 1195, which states that IP addresses are not required on each interface.
Note
Examples
In the following example, the first ATM interface is given the Ethernet 0/0 address:
DSLAM(config)#interface ethernet 0/0DSLAM(config-if)#ip address 131.108.6.6 255.255.255.0!DSLAM(config)#interface atm 0/1DSLAM(config-if)#ip unnumbered ethernet 0/0Related Commands
None.
ip vrf
To configure a VPN routing/forwarding (VRF) routing table, use the ip vrf global configuration command. To remove a VRF routing table, use the no form of this command.
ip vrf vrf-name
no ip vrf vrf-name
Syntax Description
Defaults
No VRFs are defined. No import or export lists are associated with a VRF. No route maps are associated with a VRF.
Command Modes
Router configuration
Global configuration
Command History
Usage Guidelines
The ip vrf vrf-name command creates a VRF routing table and a CEF (forwarding) table, both named vrf-name. The default route distinguisher value route-distinguisher is associated with these tables.
Examples
The following example shows how to import a route map to a VRF:
DSLAM(router-config)# ip vrf vpn1DSLAM(config-vrf)# rd 100:2DSLAM(config-vrf)# route-target both 100:2DSLAM(config-vrf)# route-target import 100:1Related Commands
ip vrf forwarding
To associate a VRF with an interface or subinterface, use the ip vrf forwarding interface configuration command. To disassociate a VRF, use the no form of this command.
ip vrf forwarding vrf-name
no ip vrf forwarding vrf-name
Syntax Description
Defaults
The default for an interface is the global routing table.
Command Modes
Global configuration
Interface configuration
Command History
Usage Guidelines
Use this command to associate an interface with a VRF. Executing this command on an interface removes the IP address. You should reconfigure the IP address.
Examples
The following example shows how to link a VRF to ATM interface 1/1:
DSLAM(config)# interface atm1/1DSLAM(config-if)# ip vrf forwarding vpn1Related Commands
lbo
To set the line build-out to various lengths, use the lbo interface configuration command. To restore the default values, use the no form of this command.
lbo {short {133 | 266 | 399 | 533 | 655} | long {gain10 | gain36} {0db | -7.5db | -15db | -22.5db}}
no lbo
Syntax Description
Defaults
The default setting is long haul with gain36 and 0 dB (lbo long gain36 0db).
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is applicable to E1 and T1 links.
Examples
The following example shows how to select long as the cable length.
DSLAM(config)# interface atm 0/2DSLAM(config-if)# lbo long gain36 -15dbThe following example shows how to select short as the cable length.
DSLAM(config)# interface atm 0/2DSLAM(config-if)# lbo short 266Related Commands
lease
To configure the duration of the lease for an IP address that is assigned from a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server to a DHCP client, use the lease DHCP pool configuration command. Use the no form of this command to restore the default value.
lease {days [hours][minutes] | infinite}
no lease
Syntax Description
Defaults
One day
Command Modes
DHCP pool configuration
Command History
Examples
The following example shows a 1-day lease:
DSLAM#configure terminalDSLAM(config)# ip dhcp pool testDSLAM(dhcp-config)#lease 1The following example shows a 1-hour lease:
DSLAM#configure terminalDSLAM(config)# ip dhcp pool testDSLAM(dhcp-config)#lease 0 1The following example shows a 1-minute lease:
DSLAM#configure terminalDSLAM(config)# ip dhcp pool testDSLAM(dhcp-config)#lease 0 0 1The following example shows an infinite (unlimited) lease:
DSLAM#configure terminalDSLAM(config)# ip dhcp pool testDSLAM(dhcp-config)#lease infiniteRelated Commands
ip dhcp pool
Configures a DHCP address pool on a Cisco IOS DHCP server and enters DHCP pool configuration mode.
linecode
To select the line code type of the T1/E1 link, use the linecode interface configuration command. To restore the default values, use the no form of this command.
linecode {ami | b8zs | hdb3}
no linecode {ami | b8zs | hdb3}
Syntax Description
Defaults
T1 = b8zs
E1 = hdb3
Command Modes
Interface configuration
Command History
Usage Guidelines
Use this command to match the line code of the far end device.
Examples
The following example specifies AMI as the line code type:
DSLAM(config)# interface atm 0/3DSLAM(config-if)# linecode amiRelated Commands
loopback
To enable a loopback on a port, use the loopback interface configuration command. To disable the loopback, use the no form of the command.
loopback {diagnostic | line | payload}
loopback [diagnostic | line] [protection | working | <cr>]
no loopback
Syntax Description
Defaults
Disabled
Command Modes
Interface configuration
Command History
12.0(5)DA
This command was introduced.
12.1(7)DA
The keywords working and protection were added.
Usage Guidelines
If you enable or disable loopbacks, the port does not untrain or retrain. However, if you remove a loopback, the port retrains. The working and protection keywords are available only when you are configuring loopback on a SONET port.
Examples
This command enables ATM local loopback for port 1 of slot 20, then disables the loopback:
DSLAM# configure terminalDSLAM(config)# interface atm 20/1DSLAM(config-if)# loopback diagnosticDSLAM(config-if)# no loopback diagnosticThis command enables a line loopback for the trunk port:
DSLAM# configure terminalDSLAM(config)# interface atm 0/1DSLAM(config-if)# loopback lineThe following example enables a loopback on atm 0/1, on the fiber local to the NI-2 card in slot 11:
DSLAM> enableDSLAM# configure terminalDSLAM(config)# interface atm 0/1DSLAM(config-if)# loopback diagnostic protectionRelated Commands
Posted: Thu May 27 13:36:51 PDT 2004
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