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Informazioni su come configurare il protocollo IP Enhanced IGRP, compresi i comandi disponibili e le impostazioni da tenere in considerazione. Il documento include esempi di configurazione e consigli utili per ottenere il miglior risultato.
Tipologia: Guide, Progetti e Ricerche
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Network Protocols Command Reference, Part 1
Use the commands in this chapter to configure and monitor IP Enhanced IGRP. For configuration information and examples, refer to the “Configuring IP Enhanced IGRP” chapter of the Network Protocols Configuration Guide, Part 1.
auto-summary (Enhanced IGRP)
Network Protocols Command Reference, Part 1
To restore the default behavior of automatic summarization of subnet routes into network-level routes, use the auto-summary command in router configuration mode. To disable this function and transmit subprefix routing information across classful network boundaries, use the no form of this command.
auto-summary
no auto-summary
Syntax Description This command has no arguments or keywords.
Defaults The behavior of this command is enabled by default (the software summarizes subprefixes to the classful network boundary when crossing classful network boundaries).
Command Modes Router configuration
Command History
Usage Guidelines Route summarization reduces the amount of routing information in the routing tables.
By default, BGP does not accept subnets redistributed from IGP. To advertise and carry subnet routes in BGP, use an explicit network command or the no auto-summary command. If you disable auto-summarization and have not entered a network command, you will not advertise network routes for networks with subnet routes unless they contain a summary route. IP Enhanced IGRP summary routes are given an administrative value of 5. You cannot configure this value. RIP Version 1 always uses automatic summarization. If you are using RIP Version 2, you can turn off automatic summarization by specifying no auto-summary. Disable automatic summarization if you must perform routing between disconnected subnets. When automatic summarization is off, subnets are advertised.
Examples The following example disables automatic summarization for process eigrp 109:
router eigrp 109 no auto-summary
Related Commands
Release Modification 10.0 This command was introduced.
Command Description ip summary-address eigrp
Configures a summary aggregate address for a specified interface.
default-information
Network Protocols Command Reference, Part 1
To control the candidate default routing information between IGRP or Enhanced IGRP processes, use the default-information command in router configuration mode. To suppress IGRP or Enhanced IGRP candidate information in incoming or outbound updates, use the no default-information in command.
default-information { in | out } { access-list-number | name }
no default-information { in | out }
Syntax Description
Defaults Normally, exterior routes are always accepted and default information is passed between IGRP or Enhanced IGRP processes when doing redistribution.
Command Modes Router configuration
Command History
Usage Guidelines The default network of 0.0.0.0 used by RIP cannot be redistributed by IGRP or Enhanced IGRP.
Examples The following example allows IGRP exterior or default routes to be received by the IGRP process in autonomous system 23: router igrp 23 default-information in
The following example allows IP Enhanced IGRP exterior or default routes to be received by the IP Enhanced IGRP process in autonomous system 23: router eigrp 23 default-information in
in Allows IGRP or Enhanced IGRP exterior or default routes to be received by an IGRP process. out Allows IGRP or Enhanced IGRP exterior routes to be advertised in updates. access-list-number | name Number or name of an access list. It can be a number in the range 1 to 99 or an access list name.
Release Modification 10.0 This command was introduced. 11.2 The access-list-number and name arguments were added.
default-metric (Enhanced IGRP)
Network Protocols Command Reference, Part 1
To set metrics for IGRP or Enhanced IGRP, use this form of the default-metric command in router configuration mode. To remove the metric value and restore the default state, use the no form of this command.
default-metric bandwidth delay reliability loading mtu
no default-metric bandwidth delay reliability loading mtu
Syntax Description
Defaults Only connected routes and interface static routes can be redistributed without a default metric.
Command Modes Router configuration
Command History
Usage Guidelines A default metric is required to redistribute a protocol into IGRP or Enhanced IGRP, unless you use the redistribute command. Automatic metric translations occur between IGRP and Enhanced IGRP. You do not need default metrics to redistributed IGRP or Enhanced IGRP into itself. Metric defaults have been carefully set to work for a wide variety of networks. Take great care when changing these values. Keeping the same metrics is supported only when redistributing from IGRP, Enhanced IGRP, or static routes.
bandwidth Minimum bandwidth of the route in kilobits per second. It can be 0 or any positive integer. delay Route delay in tens of microseconds. It can be 0 or any positive number that is a multiple of 39.1 nanoseconds. reliability Likelihood of successful packet transmission expressed as a number between 0 and 255. The value 255 means 100 percent reliability; 0 means no reliability. loading Effective bandwidth of the route expressed as a number from 0 to 255 (255 is 100 percent loading). mtu Minimum maximum transmission unit (MTU) size of the route in bytes. It can be 0 or any positive integer.
Release Modification 10.0 This command was introduced.
distance eigrp
Network Protocols Command Reference, Part 1
To allow the use of two administrative distances—internal and external—that could be a better route to a node, use the distance eigrp command in router configuration mode. To reset these values to their defaults, use the no form of this command.
distance eigrp internal-distance external-distance
no distance eigrp
Syntax Description
Defaults internal-distance : 90
external-distance : 170
Command Modes Router configuration
Command History
Usage Guidelines An administrative distance is a rating of the trustworthiness of a routing information source, such as an individual router or a group of routers. Numerically, an administrative distance is an integer between 0 and 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored. Use the distance eigrp command if another protocol is known to be able to provide a better route to a node than was actually learned via external Enhanced IGRP or if some internal routes should really be preferred by Enhanced IGRP. Table 29 lists the default administrative distances.
internal-distance Administrative distance for Enhanced IGRP internal routes. Internal routes are those that are learned from another entity within the same autonomous system. The distance can be a value from 1 to 255. external-distance Administrative distance for Enhanced IGRP external routes. External routes are those for which the best path is learned from a neighbor external to the autonomous system. The distance can be a value from 1 to 255.
Release Modification 10.0 This command was introduced.
Table 29 Default Administrative Distances
Route Source Default Distance Connected interface 0 Static route 1 Enhanced IGRP summary route
distance eigrp
Network Protocols Command Reference, Part 1
To display the default administrative distance for a specified routing process, use the show ip protocols EXEC command.
Examples In the following example, the router eigrp global configuration command sets up Enhanced IGRP routing in autonomous system number 109. The network router configuration commands specify Enhanced IGRP routing on networks 192.168.7.0 and 172.16.0.0. The distance eigrp command sets the administrative distance of all EIGRP internal routes to 80 and all EIGRP external routes to 130. Router(config)# router eigrp 109 Router(router-config)# network 192.168.7. Router(router-config)# network 172.16.0. Router(router-config)# distance eigrp 80 130
Note You cannot set the administrative distance in EIGRP against certain routes or sources, as you can with other protocols. The command does not work this way with EIGRP.
Related Commands
External BGP 20 Internal Enhanced IGRP 90 IGRP 100 OSPF 110 IS-IS 115 RIP 120 EGP 140 EIGRP external route 170 Internal BGP 200 Unknown 255
Table 29 Default Administrative Distances (continued)
Route Source Default Distance
Command Description show ip protocols Displays the parameters and current state of the active routing protocol process.
ip authentication key-chain eigrp
Network Protocols Command Reference, Part 1
To enable authentication of IP Enhanced IGRP packets, use the ip authentication key-chain eigrp command in interface configuration mode. To disable such authentication, use the no form of this command.
ip authentication key-chain eigrp autonomous-system key-chain
no ip authentication key-chain eigrp autonomous-system key-chain
Syntax Description
Defaults No authentication is provided for Enhanced IGRP packets.
Command Modes Interface configuration
Command History
Examples The following example applies authentication to autonomous system 2 and identifies a key chain named SPORTS: ip authentication key-chain eigrp 2 SPORTS
Related Commands
autonomous-system Autonomous system to which the authentication applies. key-chain Name of the authentication key chain.
Release Modification 11.2 F This command was introduced.
Command Description accept-lifetime Sets the time period during which the authentication key on a key chain is received as valid. ip authentication mode eigrp
Specifies the type of authentication used in IP Enhanced IGRP packets. key Identifies an authentication key on a key chain. key chain Enables authentication of routing protocols. key-string (authentication) Specifies the authentication string for a key. send-lifetime Sets the time period during which an authentication key on a key chain is valid to be sent.
ip authentication mode eigrp
Network Protocols Command Reference, Part 1
To specify the type of authentication used in IP Enhanced IGRP packets, use the ip authentication mode eigrp command in interface configuration mode. To disable that type of authentication, use the no form of this command.
ip authentication mode eigrp autonomous-system md
no ip authentication mode eigrp autonomous-system md
Syntax Description
Defaults No authentication is provided for IP Enhanced IGRP packets.
Command Modes Interface configuration
Command History
Usage Guidelines Configure authentication to prevent unapproved sources from introducing unauthorized or false routing messages. When authentication is configured, an MD5 keyed digest is added to each Enhanced IGRP packet in the specified autonomous system.
Examples The following example configures the interface to use MD5 authentication in Enhanced IGRP packets in autonomous system 10: ip authentication mode eigrp 10 md
Related Commands
autonomous-system Autonomous system number. md5 Keyed MD5 authentication.
Release Modification 11.2 F This command was introduced.
Command Description accept-lifetime Sets the time period during which the authentication key on a key chain is received as valid. ip authentication key-chain eigrp
Enables authentication of IP Enhanced IGRP packets.
key Identifies an authentication key on a key chain. key chain Enables authentication of routing protocols. key-string (authentication) Specifies the authentication string for a key. send-lifetime Sets the time period during which an authentication key on a key chain is valid to be sent.
ip hello-interval eigrp
Network Protocols Command Reference, Part 1
To configure the hello interval for the Enhanced IGRP routing process designated by an autonomous system number, use the ip hello-interval eigrp command in interface configuration mode. To restore the default value, use the no form of this command.
ip hello-interval eigrp autonomous-system-number seconds
no ip hello-interval eigrp autonomous-system-number seconds
Syntax Description
Defaults For low-speed, NBMA networks: 60 seconds
For all other networks: 5 seconds
Command Modes Interface configuration
Command History
Usage Guidelines The default of 60 seconds applies only to low-speed, nonbroadcast, multiaccess (NBMA) media. Low speed is considered to be a rate of T1 or slower, as specified with the bandwidth interface configuration command. Note that for the purposes of Enhanced IGRP, Frame Relay and SMDS networks may or may not be considered to be NBMA. These networks are considered NBMA if the interface has not been configured to use physical multicasting; otherwise, they are considered not to be NBMA.
Examples The following example sets the hello interval for Ethernet interface 0 to 10 seconds:
interface ethernet 0 ip hello-interval eigrp 109 10
Related Commands
autonomous-system-number Autonomous system number. seconds Hello interval, in seconds.
Release Modification 10.0 This command was introduced.
Command Description bandwidth Sets a bandwidth value for an interface. ip hold-time eigrp Configures the hold time for a particular IP Enhanced IGRP routing process designated by the autonomous system number.
ip hold-time eigrp
Network Protocols Command Reference, Part 1
To configure the hold time for a particular Enhanced IGRP routing process designated by the autonomous system number, use the ip hold-time eigrp command in interface configuration mode. To restore the default value, use the no form of this command.
ip hold-time eigrp autonomous-system-number seconds
no ip hold-time eigrp autonomous-system-number seconds
Syntax Description
Defaults For low-speed, NBMA networks: 180 seconds
For all other networks: 15 seconds
Command Modes Interface configuration
Command History
Usage Guidelines On very congested and large networks, the default hold time might not be sufficient time for all routers and access servers to receive hello packets from their neighbors. In this case, you may want to increase the hold time. We recommend that the hold time be at least three times the hello interval. If a router does not receive a hello packet within the specified hold time, routes through this router are considered unavailable. Increasing the hold time delays route convergence across the network. The default of 180 seconds hold time and 60 seconds hello interval apply only to low-speed, nonbroadcast, multiaccess (NBMA) media. Low speed is considered to be a rate of T1 or slower, as specified with the bandwidth interface configuration command.
Examples The following example sets the hold time for Ethernet interface 0 to 40 seconds:
interface ethernet 0 ip hold-time eigrp 109 40
Related Commands
autonomous-system-number Autonomous system number. seconds Hold time, in seconds.
Release Modification 10.0 This command was introduced.
Command Description bandwidth Sets a bandwidth value for an interface. ip hello-interval eigrp Configures the hello interval for the IP Enhanced IGRP routing process designated by an autonomous system number.
ip summary-address eigrp
Network Protocols Command Reference, Part 1
To configure a summary aggregate address for a specified interface, use the ip summary-address eigrp command in interface configuration mode. To disable a configuration, use the no form of this command.
ip summary-address eigrp autonomous-system-number address mask
no ip summary-address eigrp autonomous-system-number address mask
Syntax Description
Defaults No summary aggregate addresses are predefined.
Command Modes Interface configuration
Command History
Usage Guidelines Enhanced IGRP summary routes are given an administrative distance value of 5. You cannot configure this value.
Examples The following example sets the IP summary aggregate address for Ethernet interface 0:
interface ethernet 0 ip summary-address eigrp 109 192.1.0.0 255.255.0.
Related Commands
autonomous-system-number Autonomous system number. address IP summary aggregate address to apply to an interface. mask Subnet mask.
Release Modification 10.0 This command was introduced.
Command Description auto-summary (Enhanced IGRP) Restores the default behavior of automatic summarization of subnet routes into network-level routes.
metric weights (Enhanced IGRP)
Network Protocols Command Reference, Part 1
To allow the tuning of the IGRP or Enhanced IGRP metric calculations, use the metric weights command in router configuration mode. To reset the values to their defaults, use the no form of this command.
metric weights tos k1 k2 k3 k4 k
no metric weights
Syntax Description
Defaults tos : 0
k1 : 1 k2 : 0 k3 : 1 k4 : 0 k5 : 0
Command Modes Router configuration
Command History
Usage Guidelines Use this command to alter the default behavior of IGRP routing and metric computation and allow the tuning of the IGRP metric calculation for a particular type of service (TOS). If k5 equals 0, the composite IGRP or Enhanced IGRP metric is computed according to the following formula: metric = [k1 * bandwidth + (k2 * bandwidth)/(256 - load) + k3 * delay]
If k5 does not equal zero, an additional operation is done: metric = metric * [k5 / (reliability + k4)]
Bandwidth is inverse minimum bandwidth of the path in bits per second scaled by a factor of 2.56 × 10 12. The range is from a 1200-bps line to 10 terabits per second. Delay is in units of 10 microseconds. This gives a range of 10 microseconds to 168 seconds. A delay of all ones indicates that the network is unreachable.
tos Type of service must always be zero. k1k2 k3 k4 k5 Constants that convert an IGRP or EIGRP metric vector into a scalar quantity.
Release Modification 10.0 This command was introduced.
network (Enhanced IGRP)
Network Protocols Command Reference, Part 1
To specify a list of networks for the Enhanced IGRP routing process, use this form of the network command in router configuration mode. To remove an entry, use the no form of this command.
network network-number
no network network-number
Syntax Description
Defaults No networks are specified.
Command Modes Router configuration
Command History
Usage Guidelines The network number specified must not contain any subnet information. There is no limit to the number of network commands you can use on the router. IGRP or Enhanced IGRP sends updates to the interfaces in the specified network(s). Also, if an interface’s network is not specified, it will not be advertised in any IGRP or Enhanced IGRP update. The network mask can be as specific as the interface mask.
Examples The following example configures a router for IGRP and assigns autonomous system 109. The network commands indicate the networks directly connected to the router. router igrp 109 network 131.108.0. network 192.31.7.
Related Commands
network-number IP address of the directly connected networks.
Release Modification 10.0 This command was introduced.
Command Description router eigrp Configures the IP Enhanced IGRP routing process. router igrp Configures the IGRP routing process.
offset-list (Enhanced IGRP)
Network Protocols Command Reference, Part 1
To add an offset to incoming and outgoing metrics to routes learned via Enhanced IGRP, use the offset-list command in router configuration mode. To remove an offset list, use the no form of this command.
offset-list { access-list-number | name } { in | out } offset [ type number ]
no offset-list { access-list-number | name } { in | out } offset [ type number ]
Syntax Description
Defaults This command is disabled by default.
Command Modes Router configuration
Command History
Usage Guidelines The offset value is added to the routing metric. An offset-list with an interface type and interface number is considered extended and takes precedence over an offset-list that is not extended. Therefore, if an entry passes the extended offset-list and the normal offset-list, the extended offset-list’s offset is added to the metric.
Examples In the following example, the router applies an offset of 10 to the router’s delay component only to access list 21: offset-list 21 out 10
In the following example, the router applies an offset of 10 to routes learned from Ethernet interface 0: offset-list 21 in 10 ethernet 0
access-list-number | name
Standard access list number or name to be applied. Access list number 0 indicates all access lists. If offset is 0, no action is taken. For IGRP, the offset is added to the delay component only. in Applies the access list to incoming metrics. out Applies the access list to outgoing metrics. offset Positive offset to be applied to metrics for networks matching the access list. If the offset is 0, no action is taken. type (Optional) Interface type to which the offset-list is applied. number (Optional) Interface number to which the offset-list is applied.
Release Modification 10.0 This command was introduced. 10.3 The type and number arguments were added. 11.2 The name argument was added.
