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IP Routing configuration Guide, stillproud.org IOS XE Amsterdam 17.1.x (Catalyst 9500 Switches)

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Configuring EIGRP


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Configuring EIGRP

Information around EIGRP

Enhanced IGRP (EIGRP) is a stillproud.org proprietary amplified version of the IGRP. EIGRP uses the very same distance vector algorithm and distance details as IGRP; however, the convergence properties and the operating efficiency of EIGRP are significantly improved.

The convergence modern technology employs an algorithm referred to as the Diffusing update Algorithm (DUAL), which guarantees loop-free operation at every immediate throughout a path computation and allows all devices connected in a topology change to synchronize at the same time. Routers that space not affected by topology alters are not affiliated in recomputations.

IP EIGRP provides increased network width. Through RIP, the largest feasible width of her network is 15hops. Due to the fact that the EIGRP metric is big enough to support thousands the hops, the only barrier to widening the network is the transport-layer hop counter. EIGRP increments the transport regulate field only when an IP packet has traversed 15 routers and also the next hop come the location was learned through EIGRP. When a RIP path is used as the following hop come the destination, the transport control field is incremented as usual.

EIGRP IPv6

Switches support the intensified Interior Gateway Routing Protocol (EIGRP) because that IPv6. That is configured on the interfaces ~ above which the runs and also does not call for a worldwide IPv6 address. Switches running Network Essentials only support EIGRPv6 stub routing.

Before running, an instance of EIGRP IPv6 needs an latent or clear router ID. An latent router id is acquired from a local IPv6 address, so any IPv6 node always has an available router ID. However, EIGRP IPv6 can be to run in a network with only IPv6 nodes and therefore can not have an obtainable IPv6 router ID.

For configuring EIGRP for IPv6, check out the Configuring EIGRP because that IPv6 section.

For much more information around EIGRP for IPv6, check out the stillproud.org IOS IPv6 configuration Library ~ above stillproud.org.

EIGRP Features

EIGRP uses these features:

Fast convergence.

You are watching: Your routers have been configured to use eigrpv6

Incremental updates when the state of a location changes, rather of sending the entire materials of the routing table, minimizing the bandwidth required for EIGRP packets.

Less CPU usage due to the fact that full update packets need not be processed every time they room received.

Protocol-independent neighbor exploration mechanism to learn around neighboring routers.

Variable-length subnet masks (VLSMs).

Arbitrary route summarization.

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EIGRP scale to big networks.

EIGRP Components

EIGRP has these four simple components:

Neighbor discovery and also recovery is the process that routers use to dynamically learn of various other routers ~ above their straight attached networks. Routers must likewise discover once their neighbors end up being unreachable or inoperative. Ar discovery and also recovery is completed with low overhead by regularly sending small hello packets. As long as hello packets room received, the stillproud.org IOS software deserve to learn the a neighborhood is alive and also functioning. When this status is determined, the neighboring routers have the right to exchange routing information.

The trustworthy transport protocol is responsible because that guaranteed, ordered shipment of EIGRP packets to every neighbors. It supports intermixed infection of multicast and unicast packets. Some EIGRP packets should be sent reliably, and others need not be. Because that efficiency, integrity is noted only as soon as necessary. Because that example, top top a multiaccess network that has actually multicast ability (such together Ethernet), the is not important to send hellos reliably to all next-door neighbors individually. Therefore, EIGRP sends a single multicast hello with an point out in the packet informing the receivers that the packet need not be acknowledged. Other varieties of packets (such together updates) need acknowledgment, i beg your pardon is displayed in the packet. The trusted transport has a provision come send multicast packets conveniently when there room unacknowledged packets pending. Doing so help ensure the convergence time stays low in the visibility of varying rate links.

The dual finite state machine embodies the decision procedure for all route computations. It tracks all paths advertised by all neighbors. Dual uses the distance info (known as a metric) to select efficient, loop-free paths. Twin selects routes to be put into a routing table based on feasible successors. A successor is a neighboring router provided for packet forwarding that has actually a least-cost route to a destination that is guaranteed not to be part of a routing loop. As soon as there space no feasible successors, yet there are neighbors advertising the destination, a recomputation need to occur. This is the procedure whereby a new successor is determined. The lot of time it takes come recompute the course affects the convergence time. Recomputation is processor-intensive; it is helpful to avoid recomputation if it is not necessary. Once a topology change occurs, double tests for feasible successors. If there space feasible successors, that uses any type of it finds to protect against unnecessary recomputation.

The protocol-dependent modules room responsible because that network class protocol-specific tasks. An example is the IP EIGRP module, which is responsible for sending and receiving EIGRP packets that are encapsulated in IP. The is likewise responsible because that parsing EIGRP packets and informing dual of the brand-new information received. EIGRP asks double to do routing decisions, however the results are save in the IP routing table. EIGRP is also responsible because that redistributing paths learned by other IP routing protocols.

Note

To permit EIGRP, the standalone switch or energetic switch must be running the Network benefit license.

EIGRP non-saw Forwarding

The device supports 2 levels of EIGRP non-saw forwarding:

EIGRP NSF Awareness

EIGRP NSF ability

EIGRP NSF Awareness

The Network advantage license supports EIGRP NSF Awareness for IPv4. When the neighboring router is NSF-capable, the class 3 maker continues to front packets from the neighboring router throughout the interval in between the main Route Processor (RP) in a router failing and also the backup RP acquisition over, or while the major RP is manually reloaded because that a nondisruptive software program upgrade. This attribute cannot it is in disabled.

EIGRP NSF ability

The Network advantage license supports EIGRP stillproud.org NSF routing to rate up convergence and to eliminate traffic ns after an active switch change.

The Network benefit license likewise supports EIGRP NSF-capable routing for IPv4 for far better convergence and also lower web traffic loss following an energetic switch change. Once an EIGRP NSF-capable active switch restarts or a brand-new active move starts up and NSF restarts, the machine has no neighbors, and the topology table is empty. The device must bring up the interfaces, reacquire neighbors, and rebuild the topology and routing tables without interrupting the website traffic directed toward the an equipment stack. EIGRP peer routers preserve the paths learned native the brand-new active switch and continue forwarding traffic through the NSF restart process.

To avoid an adjacency reset through the neighbors, the new active switch provides a brand-new Restart (RS) bit in the EIGRP packet header to display the restart. When the neighbor receives this, that synchronizes the stack in the peer list and maintains the adjacency with the stack. The neighbor then sends its topology table to the active switch through the RS bit collection to display that the is NSF-aware and also is aiding the brand-new active switch.

If at the very least one the the ridge peer neighbors is NSF-aware, the energetic switch receive updates and rebuilds that database. Every NSF-aware neighbor sends out an end of table (EOT) marker in the last upgrade packet to note the end of the table content. The active switch establish the convergence when it receive the EOT marker, and it then starts sending updates. Once the active switch has received all EOT mite from its next-door neighbors or when the NSF converge timer expires, EIGRP informs the routing info database (RIB) the convergence and also floods that is topology table to every NSF-aware peers.

EIGRP Stub Routing

The EIGRP stub routing function improves network stability, reduces resource utilization, and also simplifies the stub device configuration.

Stub routing is commonly used in hub-and-spoke network topologies. In a hub-and-spoke network, one or an ext end (stub) networks are associated to a remote machine (the spoke) that is linked to one or much more distribution tools (the hub). The remote maker is surrounding to one or much more distribution devices. The just route because that IP web traffic to reach the remote an equipment is v a circulation device. This kind of configuration is frequently used in WAN topologies, wherein the distribution an equipment is directly connected to a WAN. The distribution an equipment can be linked to plenty of remote devices, i beg your pardon is frequently the case. In a hub-and-spoke topology, the remote machine must forward all nonlocal traffic to a circulation device, so it becomes unnecessary for the remote device to have a complete routing table. Generally, the distribution maker need no send anything an ext than a default course to the remote device.

When using the EIGRP stub routing feature, you must configure the distribution and remote devices to use EIGRP and also configure just the remote an equipment as a stub. Only specified routes are propagated native the far (stub) device. The stub maker responds to every queries for summaries, connected routes, redistributed static routes, outside routes, and internal paths with the message “inaccessible.” A maker that is configured as a stub will send a one-of-a-kind peer information packet to all neighboring devices to report its standing as a stub device.

Any neighbor that receives a packet informing the of the stub status will no query the stub maker for any type of routes, and a device that has actually a stub peer will certainly not query that peer. The stub device will depend on the distribution machine to send suitable updates to every peers.

The figure listed below shows a basic hub-and-spoke network.

number 1. Simple Hub-and-Spoke Network
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The stub routing attribute by chin does not protect against routes from gift advertised come the far device. In the over example, the remote device can accessibility the this firm network and also the internet only with the circulation device. Having a finish route table on the remote machine would offer no sensible purpose since the path to the that company network and the net would always be with the distribution device. The big route table would certainly only reduce the quantity of memory required by the remote device. Bandwidth and memory can be conserved through summarizing and also filtering routes in the distribution device. The remote an equipment need not get routes that have actually been learned from other networks because the remote machine must send all nonlocal traffic, regardless of the destination, to the distribution device. If a true stub network is desired, the distribution machine should it is in configured to send just a default course to the remote device. The EIGRP stub routing attribute does not automatically enable summarization on circulation devices. In most cases, the network administrator will need to configure summarization on distribution devices.

Note

When configuring the distribution maker to send only a default course to the remote device, you need to use the ip classless command top top the remote device. By default, the ip classless command is enabled in every stillproud.org photos that assistance the EIGRP stub routing feature.

Without the EIGRP stub routing feature, also after paths that are sent from the distribution device to the remote an equipment have been filtered or summarized, a problem might occur. If a path is shed somewhere in the that company network, EIGRP might send a query come the circulation device, which in turn would send a query come the far device, also if paths are gift summarized. If there is a communication problem (over the WAN link) between the distribution maker and the remote device, an EIGRP grounding in energetic (SIA) problem could occur and also cause instability in other places in the network. The EIGRP stub routing feature permits a network administrator to avoid queries native being sent to the remote device.

EIGRPv6 Stub Routing

The EIGRPv6 stub routing feature, reduces source utilization by relocating routed website traffic closer to the finish user.

In a network utilizing EIGRPv6 stub routing, the only allowable course for IPv6 traffic to the user is with a switch that is configured with EIGRPv6 stub routing. The switch sends out the routed web traffic to interfaces that are configured as user interfaces or are connected to other devices.

When utilizing EIGRPv6 stub routing, you have to configure the distribution and remote routers to use EIGRPv6 and to configure just the switch as a stub. Only specified routes are propagated indigenous the switch. The move responds to all queries for summaries, connected routes, and routing updates.

Any neighbor the receives a packet informing that of the stub condition does not query the stub router for any type of routes, and also a router that has actually a stub peer does no query the peer. The stub router relies on the circulation router come send the suitable updates to every peers.

In the figure given below, switch B is configured as an EIGRPv6 stub router. Switches A and also C are connected to the remainder of the WAN. Move B advertises connected, static, redistribution, and summary routes to switch A and also C. Switch B does no advertise any type of routes learned from switch A (and the reverse).

figure 2. EIGRP Stub Router construction
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For much more information about EIGRPv6 stub routing, watch “Implementing EIGRP because that IPv6” section of the stillproud.org IOS IP configuration Guide, Volume 2 the 3: Routing Protocols, relax 12.4.

How to Configure EIGRP

To develop an EIGRP routing process, girlfriend must enable EIGRP and associate networks. EIGRP sends out updates to the interfaces in the specified networks. If you do not point out an user interface network, that is not advertised in any EIGRP update.

Note

If you have routers on your network that room configured for IGRP, and also you desire to change to EIGRP, you should designate shift routers that have both IGRP and also EIGRP configured. In this cases, perform procedures 1 with 3 in the following section and likewise see the “Configuring separation Horizon” section. You need to use the exact same AS number for courses to be automatically redistributed.

Default EIGRP Configuration

Table 1. Default EIGRP construction

Feature

Default setting

Auto summary

Disabled.

Default-information

Exterior paths are accepted and default details is passed in between EIGRP processes as soon as doing redistribution.

Default metric

Only associated routes and also interface revolution routes deserve to be redistributed there is no a default metric. The metric includes:

Bandwidth: 0 or greater kb/s.

Delay (tens the microseconds): 0 or any type of positive number that is a lot of of 39.1 nanoseconds.

Reliability: any number between 0 and 255 (255 method 100percent reliability).

Loading: effective bandwidth as a number between 0 and 255 (255 is 100 percent loading).

MTU: maximum transmission unit dimension of the path in bytes. 0 or any kind of positive integer.

Distance

Internal distance: 90.

External distance: 170.

EIGRP log-neighbor transforms

Disabled. No adjacency changes logged.

IP authentication key-chain

No authentication provided.

IP authentication setting

No authentication provided.

IP bandwidth-percent

50 percent.

IP hello term

For low-speed nonbroadcast multiaccess (NBMA) networks: 60seconds; all other networks: 5seconds.

IP hold-time

For low-speed NBMA networks: 180 seconds; all various other networks: 15seconds.

IP split-horizon

Enabled.

IP summary attend to

No summary accumulation addresses room predefined.

Metric weights

tos: 0; k1 and also k3: 1; k2, k4, and also k5: 0

Network

None specified.

Nonstop Forwarding (NSF) Awareness

Enabled because that IPv4 top top switches to run the Network advantage license. Allows Layer 3 switches to continue forwarding packets from a neighboring NSF-capable router throughout hardware or software changes.

NSF ability

Disabled.

Note

The device supports EIGRP NSF-capable routing because that IPv4.

Offset-list

Disabled.

Router EIGRP

Disabled.

Set metric

No metric set in the path map.

Traffic-share

Distributed proportionately come the ratios the the metrics.

Variance

1 (equal-cost load-balancing).

Configuring straightforward EIGRP Parameters

Procedure Command or action Purpose
Step1

permit

Example:

Device>enable

permits privileged EXEC mode.

enter your password if prompted.

Step2

configure terminal

Example:

Device#configure terminal

Enters worldwide configuration mode.

Step3

router eigrp autonomous-system

Example:

Device(config)#router eigrp 10

enables an EIGRP routing process, and enter router configuration mode. The together number identifies the courses to various other EIGRP routers and is used to sign routing information.

Step4

nsf

Example:

Device(config-router)#nsf

(Optional) allows EIGRP NSF. Go into this command top top the active switch and also on all of its peers.

Step5

network network-number

Example:

Device(config-router)#network 192.168.0.0

combine networks through an EIGRP routing process. EIGRP sends out updates to the interfaces in the specified networks.

Step6

eigrp log-neighbor-changes

Example:

Device(config-router)#eigrp log-neighbor-changes

(Optional) enables logging the EIGRP neighbor changes to screen routing mechanism stability.

Step7

metric weights tos k1 k2 k3 k4 k5

Example:

Device(config-router)#metric weights 0 2 0 2 0 0

(Optional) adjust the EIGRP metric. Although the defaults have actually been carefully set to provide excellent procedure in many networks, you can change them.

Caution

Setting metrics is complicated and is not recommended without guidance native an knowledgeable network designer.

Step8

offset-list out balance out

Example:

Device(config-router)#offset-list 21 out 10 (Optional) applies an offset list come routing metrics to increase incoming and outgoing metrics to courses learned v EIGRP. You can limit the offset list v an accessibility list or one interface.

Step9

auto-summary

Example:

Device(config-router)#auto-summary (Optional) enables automatic summarization the subnet routes into network-level routes.

Step10

interface interface-id

Example:

Device(config-router)#interface gigabitethernet 1/0/1 Enters user interface configuration mode, and also specifies the layer 3 user interface to configure.

Step11

ip summary-address eigrp autonomous-system-number deal with mask

Example:

Device(config-if)#ip summary-address eigrp 1 192.168.0.0 255.255.0.0 (Optional) Configures a review aggregate.

Step12

end

Example:

Device(config-if)#end return to privileged EXEC mode.

Step13

show ip protocols

Example:

Device#show ip protocols Verifies her entries.

For NSF awareness, the output shows:

*** IP Routing is NSF conscious *** EIGRP NSF enabled

Step14

copy running-config startup-config

Example:

Device#copy running-config startup-config (Optional) conserves your entries in the configuration file.

Configuring EIGRP Interfaces

Other optional EIGRP parameters deserve to be configured on an user interface basis.

Procedure Command or activity Purpose
Step1

allow

Example:

Device>enable

enables privileged EXEC mode.

get in your password if prompted.

Step2

configure terminal

Example:

Device#configure terminal

Enters worldwide configuration mode.

Step3

interface interface-id

Example:

Device(config)#interface gigabitethernet 1/0/1

Enters interface configuration mode, and specifies the class 3 interface to configure.

Step4

ip bandwidth-percent eigrp percent

Example:

Device(config-if)#ip bandwidth-percent eigrp 60

(Optional) Configures the percent of bandwidth that have the right to be provided by EIGRP on one interface. The default is 50 percent.

Step5

ip summary-address eigrp autonomous-system-number resolve mask

Example:
Step6

ip hello-interval eigrp autonomous-system-number seconds

Example:

Device(config-if)#ip hello-interval eigrp 109 10

(Optional) adjust the hello time interval because that an EIGRP routing process. The selection is 1 come 65535 seconds. The default is 60 secs for low-speed NBMA networks and 5 seconds for all various other networks.

Step7

ip hold-time eigrp autonomous-system-number secs

Example:

Device(config-if)#ip hold-time eigrp 109 40

(Optional) readjust the hold time interval because that an EIGRP routing process. The variety is 1 to 65535 seconds. The default is 180 secs for low-speed NBMA networks and 15 seconds for all various other networks.

Caution

Do not readjust the host time there is no consulting stillproud.org technological support.

Step8

no ip split-horizon eigrp autonomous-system-number

Example:

Device(config-if)#no ip split-horizon eigrp 109 (Optional) Disables break-up horizon to allow route information to be advertised by a router out any kind of interface indigenous which that details originated.

Step9

end

Example:

Device(config)#end return to privileged EXEC mode.

Step10

show ip eigrp user interface

Example:

Device#show ip eigrp interface display screens which interfaces EIGRP is energetic on and also information about EIGRP relating come those interfaces.

Step11

copy running-config startup-config

Example:

Device#copy running-config startup-config (Optional) saves your entries in the construction file.

Configuring EIGRP for IPv6

Before configuring the move to run IPv6 EIGRP, allow routing by entering the ip routing an international configuration command, allow the forwarding that IPv6 packets by beginning the ipv6 unicast-routing global configuration command, and allow IPv6 on any Layer 3 interfaces on which you want to permit IPv6 EIGRP.

To set an explicit router ID, usage the show ipv6 eigrp command to view the configured router IDs, and also then usage the router-id command.

As v EIGRP IPv4, you have the right to use EIGRPv6 to specify her EIGRP IPv6 interfaces and to pick a subset that those as passive interfaces. Usage the passive-interface command to make an user interface passive, and then usage the no passive-interface command top top selected interfaces to make them active. EIGRP IPv6 go not should be configured ~ above a passive interface.

For much more configuration procedures, see the “Implementing EIGRP because that IPv6” thing in the stillproud.org IOS IPv6 configuration Library on stillproud.org.

Configuring EIGRP route Authentication

EIGRP route authentication gives MD5 authentication of routing updates indigenous the EIGRP routing protocol to prevent the introduction of unauthorized or false routing messages from unapproved sources.

Procedure Command or activity Purpose
Step1

enable

Example:

Device>enable

allows privileged EXEC mode.

enter your password if prompted.

Step2

configure terminal

Example:

Device#configure terminal

Enters global configuration mode.

Step3

interface interface-id

Example:

Device(config)#interface gigabitethernet 1/0/1

Enters interface configuration mode, and also specifies the layer 3 user interface to configure.

Step4

ip authentication mode eigrp autonomous-system md5

Example:

Device(config-if)#ip authentication setting eigrp 104 md5

permits MD5 authentication in IP EIGRP packets.

Step5

ip authentication key-chain eigrp autonomous-system key-chain

Example:

Device(config-if)#ip authentication key-chain eigrp 105 chain1

allows authentication that IP EIGRP packets.

Step6

exit

Example:

Device(config-if)#exit

returns to an international configuration mode.

Step7

key chain name-of-chain

Example:

Device(config)#key chain chain1

identify a an essential chain and enter key-chain configuration mode. Match the surname configured in action 4.

Step8

key number

Example:

Device(config-keychain)#key 1

In key-chain configuration mode, determine the an essential number.

Step9

key-string text

Example:

Device(config-keychain-key)#key-string key1

In key-chain vital configuration mode, identify the vital string.

Step10

accept-lifetime start-time duration seconds

Example:

Device(config-keychain-key)#accept-lifetime 13:30:00 january 25 2011 expression 7200

(Optional) states the time duration during which the key can it is in received.

The start-time and end-time syntax can be one of two people hh:mm:ss Month date year or hh:mm:ss date Month year . The default is forever with the default start-time and also the faster acceptable day as January 1, 1993. The default end-time and also duration is boundless .

Step11

send-lifetime start-time term seconds

Example:

Device(config-keychain-key)#send-lifetime 14:00:00 jan 25 2011 term 3600

(Optional) mentions the time period during i beg your pardon the crucial can be sent.

The start-time and also end-time syntax have the right to be either hh:mm:ss Month date year or hh:mm:ss day Month year . The default is forever v the default start-time and also the earliest acceptable day as January 1, 1993. The default end-time and duration is boundless .

Step12

end

Example:

Device(config)#end

return to privileged EXEC mode.

Step13

show crucial chain

Example:

Device#show vital chain

display screens authentication vital information.

Step14

copy running-config startup-config

Example:

Device#copy running-config startup-config

(Optional) conserves your entries in the configuration file.

Monitoring and also Maintaining EIGRP

You deserve to delete next-door neighbors from the neighbor table. Girlfriend can also display miscellaneous EIGRP routing statistics. The table given below lists the privileged EXEC regulates for deleting neighbors and displaying statistics.

Table 2. IP EIGRP Clear and also Show commands

Command

Purpose

clear ip eigrp neighbors

Deletes next-door neighbors from the neighborhood table.

show ip eigrp user interface

Displays information about interfaces configured because that EIGRP.

show ip eigrp neighbors

Displays EIGRP found neighbors.

show ip eigrp topology | < mask>>

Displays the EIGRP topology table for a offered process.

show ip eigrp traffic

Displays the number of packets sent and also received for all or a specified EIGRP process.

Feature info for EIGRP

The complying with table provides release information around the attribute or features explained in this module. This table lists only the software application release that presented support because that a given attribute in a given software relax train. Unless detailed otherwise, succeeding releases the that software program release train also support that feature.