- Preface
- New and Changed Information
- Overview
- Configuring IPv4
- Configuring OSPFv2
- Configuring EIGRP
- Configuring Basic BGP
- Configuring Advanced BGP
- Configuring BGP Additional Paths
- Configuring RIP
- Configuring Static Routing
- Configuring Layer 3 Virtualization
- Configuring the Unicast RIB and FIB
- Configuring Route Policy Manager
- Configuring Bidirectional Forwarding Detection
- Configuring Policy-Based Routing
- Configuring HSRP
- Configuring VRRP
- Configuring Object Tracking
- IETF RFCs
- Configuring Authentication in EIGRP
- Configuring EIGRP Stub Routing
- Configuring a Summary Address for EIGRP
- Redistributing Routes into EIGRP
- Limiting the Number of Redistributed Routes
- Configuring Load Balancing in EIGRP
- Adjusting the Interval Between Hello Packets and the Hold Time
- Disabling Split Horizon
- Tuning EIGRP
Configuring EIGRP
This chapter describes how to configure the Enhanced Interior Gateway Routing Protocol ( EIGRP) on Cisco NX-OS switches.
This chapter includes the following sections:
- Information About EIGRP
- Licensing Requirements for EIGRP
- Prerequisites for EIGRP
- Guidelines and Limitations for EIGRP
- Default Settings for EIGRP
- Configuring Basic EIGRP
- Configuring Advanced EIGRP
- Configuring Virtualization for EIGRP
- Verifying the EIGRP Configuration
- Displaying EIGRP Statistics
- Configuration Examples for EIGRP
- Related Topics
- Additional References
- Feature History for EIGRP
Information About EIGRP
EIGRP combines the benefits of distance vector protocols with the features of link-state protocols. EIGRP sends out periodic hello messages for neighbor discovery. Once EIGRP learns a new neighbor, it sends a one-time update of all the local EIGRP routes and route metrics. The receiving EIGRP router calculates the route distance based on the received metrics and the locally assigned cost of the link to that neighbor. After this initial full route table update, EIGRP sends incremental updates to only those neighbors affected by the route change. This process speeds convergence and minimizes bandwidth.
EIGRP Components
EIGRP has the following basic components:
Reliable Transport Protocol
The Reliable Transport Protocol guarantees ordered delivery of EIGRP packets to all neighbors. (See the Neighbor Discovery and Recovery section.) The Reliable Transport Protocol supports the transmission of unicast packets. This provision helps to ensure that the convergence time remains low for various speed links. See the Configuring Advanced EIGRP section for details about modifying the default timers that control the unicast packet transmissions.
The Reliable Transport Protocol includes the following message types:
-
Hello—Used for neighbor discovery and recovery. By default, EIGRP sends a periodic multicast hello message on the local network at the configured hello interval. By default, the hello interval is 5 seconds.
-
Acknowledgement—Verifies reliable reception of Updates, Queries, and Replies.
-
Updates—Sends to affected neighbors when routing information changes. Updates include the route destination, address mask, and route metrics such as delay and bandwidth. The update information is stored in the EIGRP topology table.
-
Queries and Replies—Sent as necessary as part of the Diffusing Update Algorithm used by EIGRP.
Neighbor Discovery and Recovery
EIGRP uses the hello messages from the Reliable Transport Protocol to discover neighboring EIGRP routers on directly attached networks. EIGRP adds neighbors to the neighbor table. The information in the neighbor table includes the neighbor address, the interface it was learned on, and the hold time, which indicates how long EIGRP should wait before declaring a neighbor unreachable. By default, the hold time is three times the hello interval or 15 seconds.
EIGRP sends a series of Update messages to new neighbors to share the local EIGRP routing information. This route information is stored in the EIGRP topology table. After this initial transmission of the full EIGRP route information, EIGRP sends Update messages only when a routing change occurs. These Update messages contain only the new or changed information and are sent only to the neighbors affected by the change. See the EIGRP Route Updates section.
EIGRP also uses the hello messages as a keepalive to its neighbors. As long as hello messages are received, Cisco NX-OS can determine that a neighbor is alive and functioning.
Diffusing Update Algorithm
The Diffusing Update Algorithm (DUAL) calculates the routing information based on the destination networks in the topology table. The topology table includes the following information:
-
IPv4 address/mask—The network address and network mask for this destination.
-
Successors—The IP address and local interface connection for all feasible successors or neighbors that advertise a shorter distance to the destination than the current feasible distance.
-
Feasibility distance (FD)—The lowest calculated distance to the destination. The feasibility distance is the sum of the advertised distance from a neighbor plus the cost of the link to that neighbor.
DUAL uses the distance metric to select efficient, loop-free paths. DUAL selects routes to insert into the unicast Routing Information Base (RIB) based on feasible successors. When a topology change occurs, DUAL looks for feasible successors in the topology table. If there are feasible successors, DUAL selects the feasible successor with the lowest feasible distance and inserts that into the unicast RIB, avoiding unnecessary recomputation.
When there are no feasible successors but there are neighbors advertising the destination, DUAL transitions from the passive state to the active state and triggers a recomputation to determine a new successor or next-hop router to the destination. The amount of time required to recompute the route affects the convergence time. EIGRP sends Query messages to all neighbors, searching for feasible successors. Neighbors that have a feasible successor send a Reply message with that information. Neighbors that do not have feasible successors trigger a DUAL recomputation.
EIGRP Route Updates
When a topology change occurs, EIGRP sends an Update message with only the changed routing information to affected neighbors. This Update message includes the distance information to the new or updated network destination.
The distance information in EIGRP is represented as a composite of available route metrics, including bandwidth, delay, load utilization, and link reliability. Each metric has an associated weight that determines if the metric is included in the distance calculation. You can configure these metric weights. You can fine-tune link characteristics to achieve optimal paths, but we recommend that you use the default settings for most configurable metrics.
Internal Route Metrics
Internal routes are routes that occur between neighbors within the same EIGRP autonomous system. These routes have the following metrics:
-
Next hop—The IP address of the next-hop router.
-
Delay—The sum of the delays configured on the interfaces that make up the route to the destination network. Configured in tens of microseconds.
-
Bandwidth—The calculation from the lowest configured bandwidth on an interface that is part of the route to the destination.
Note | We recommend that you use the default bandwidth value. This bandwidth parameter is also used by EIGRP. |
-
MTU—The smallest maximum transmission unit value along the route to the destination.
-
Hop count—The number of hops or routers that the route passes through to the destination. This metric is not directly used in the DUAL computation.
-
Reliability—An indication of the reliability of the links to the destination.
-
Load—An indication of how much traffic is on the links to the destination.
By default, EIGRP uses the bandwidth and delay metrics to calculate the distance to the destination. You can modify the metric weights to include the other metrics in the calculation.
External Route Metrics
External routes are routes that occur between neighbors in different EIGRP autonomous systems. These routes have the following metrics:
-
Next hop—The IP address of the next-hop router.
-
Router ID—The router ID of the router that redistributed this route into EIGRP.
-
AS Number—The autonomous system number of the destination.
-
Protocol ID—A code that represents the routing protocol that learned the destination route.
-
Tag—An arbitrary tag that can be used for route maps.
-
Metric—The route metric for this route from the external routing protocol.
EIGRP and the Unicast RIB
EIGRP adds all learned routes to the EIGRP topology table and the unicast RIB. When a topology change occurs, EIGRP uses these routes to search for a feasible successor. EIGRP also listens for notifications from the unicast RIB for changes in any routes redistributed to EIGRP from another routing protocol.
Advanced EIGRP
You can use the advanced features of EIGRP to optimize your EIGRP configuration.
- Address Families
- Authentication
- Stub Routers
- Route Summarization
- Route Redistribution
- Load Balancing
- Split Horizon
- Virtualization Support
Address Families
EIGRP supports the IPv4 address family.
Address family configuration mode includes the following EIGRP features:
-
Authentication
-
AS number
-
Default route
-
Metrics
-
Distance
-
Graceful restart
-
Logging
-
Load balancing
-
Redistribution
-
Router ID
-
Stub router
-
Timers
You cannot configure the same feature in more than one configuration mode. For example, if you configure the default metric in router configuration mode, you cannot configure the default metric in address family mode
Authentication
You can configure authentication on EIGRP messages to prevent unauthorized or invalid routing updates in your network. EIGRP authentication supports MD5 authentication digest.
You can configure the EIGRP authentication per virtual routing and forwarding (VRF) instance or interface using key-chain management for the authentication keys. Key-chain management allows you to control changes to the authentication keys used by MD5 authentication digest. See the Cisco Nexus 9000 Series NX-OS Security Configuration Guide, Release 7.x, for more details about creating key-chains.
For MD5 authentication, you configure a password that is shared at the local router and all remote EIGRP neighbors. When an EIGRP message is created, Cisco NX-OS creates an MD5 one-way message digest based on the message itself and the encrypted password and sends this digest along with the EIGRP message. The receiving EIGRP neighbor validates the digest using the same encrypted password. If the message has not changed, the calculation is identical and the EIGRP message is considered valid.
MD5 authentication also includes a sequence number with each EIGRP message that is used to ensure that no message is replayed in the network.
Stub Routers
You can use the EIGRP stub routing feature to improve network stability, reduce resource usage, and simplify stub router configuration. Stub routers connect to the EIGRP network through a remote router. See the Stub Routing section.
When using EIGRP stub routing, you need to configure the distribution and remote routers to use EIGRP and configure only the remote router as a stub. EIGRP stub routing does not automatically enable summarization on the distribution router. In most cases, you need to configure summarization on the distribution routers.
Without EIGRP stub routing, even after the routes that are sent from the distribution router to the remote router have been filtered or summarized, a problem might occur. For example, if a route is lost somewhere in the corporate network, EIGRP could send a query to the distribution router. The distribution router could then send a query to the remote router even if routes are summarized. If a problem communicating over the WAN link between the distribution router and the remote router occurs, EIGRP could get stuck in active condition and cause instability elsewhere in the network. EIGRP stub routing allows you to prevent queries to the remote router.
Route Summarization
You can configure a summary aggregate address for a specified interface. Route summarization simplifies route tables by replacing a number of more-specific addresses with an address that represents all the specific addresses. For example, you can replace 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24 with one summary address, 10.1.0.0/16.
If more specific routes are in the routing table, EIGRP advertises the summary address from the interface with a metric equal to the minimum metric of the more specific routes.
Note | EIGRP does not support automatic route summarization. |
Route Redistribution
You can use EIGRP to redistribute direct routes, static routes, routes learned by other EIGRP autonomous systems, or routes from other protocols. You configure route map with the redistribution to control which routes are passed into EIGRP. A route map allows you to filter routes based on attributes such as the destination, origination protocol, route type, route tag, and so on. See Configuring Route Policy Manager.
You also configure the default metric that is used for all imported routes into EIGRP.
Load Balancing
You can use load balancing to allow a router to distribute traffic over all the router network ports that are the same distance from the destination address. Load balancing increases the utilization of network segments, which increases effective network bandwidth.
Cisco NX-OS supports the Equal Cost Multiple Paths (ECMP) feature with up to 32 equal-cost paths in the EIGRP route table and the unicast RIB. You can configure EIGRP to load balance traffic across some or all of those paths.
Note | EIGRP in Cisco NX-OS does not support unequal cost load balancing. |
Note | In the Cisco Nexus 3548 switch, ECMP is not supported on warp mode. |
Split Horizon
You can use split horizon to ensure that EIGRP never advertises a route out of the interface where it was learned.
Split horizon is a method that controls the sending of EIGRP update and query packets. When you enable split horizon on an interface, Cisco NX-OS does not send update and query packets for destinations that were learned from this interface. Controlling update and query packets in this manner reduces the possibility of routing loops.
Split horizon with poison reverse configures EIGRP to advertise a learned route as unreachable back through that the interface that EIGRP learned the route from.
EIGRP uses split horizon or split horizon with poison reverse in the following scenarios:
-
Exchanging topology tables for the first time between two routers in startup mode.
-
Advertising a topology table change.
-
Sending a query message.
By default, the split horizon feature is enabled on all interfaces.
Virtualization Support
Cisco NX-OS supports multiple instances of the EIGRP protocol that runs on the same system. EIGRP supports Virtual Routing and Forwarding instances (VRFs). By default, Cisco NX-OS places you in the default VRF unless you specifically configure another VRF. See Configuring Layer 3 Virtualization.
By default, every instance uses the same system router ID. You can optionally configure a unique router ID for each instance.
Licensing Requirements for EIGRP
The following table shows the licensing requirements for this feature:
Product |
License Requirement |
---|---|
Cisco NX-OS |
Full EIGRP requires a Enterprise Services license, however EIGRP stub requires a LAN Base Services license. For a complete explanation of the Cisco NX-OS licensing scheme and how to obtain and apply licenses, see the Cisco NX-OS Licensing Guide. |
Prerequisites for EIGRP
EIGRP has the following prerequisites:
-
You must enable the EIGRP feature (see the Enabling the EIGRP Feature section).
Guidelines and Limitations for EIGRP
EIGRP has the following configuration guidelines and limitations:
-
A metric configuration (either through the default-metric configuration option or through a route map) is required for redistribution from any other protocol, connected routes, or static routes (see Configuring Route Policy Manager).
-
Cisco NX-OS EIGRP is compatible with EIGRP in the Cisco IOS software.
-
Do not change the metric weights without a good reason. If you change the metric weights, you must apply the change to all EIGRP routers in the same autonomous system.
-
Consider using stubs for larger networks.
-
Avoid redistribution between different EIGRP autonomous systems because the EIGRP vector metric will not be preserved.
-
The no ip next-hop-self command does not guarantee reachability of the next hop.
-
The ip passive-interface eigrp command suppresses neighbors from forming.
-
Cisco NX-OS does not support IGRP or connecting IGRP and EIGRP clouds.
-
Autosummarization is not enabled by default.
-
Cisco NX-OS supports only IP.
Note | If you are familiar with the Cisco IOS CLI, be aware that the Cisco NX-OS commands for this feature might differ from the Cisco IOS commands that you would use. |
Default Settings for EIGRP
Table below lists the default settings for EIGRP parameters.
Parameters |
Default |
---|---|
Administrative distance |
|
Bandwidth percent |
50 percent |
Default metric for redistributed routes |
|
EIGRP feature |
Disabled |
Hello interval |
5 seconds |
Hold time |
15 seconds |
Equal-cost paths |
8 |
Metric weights |
1 0 1 0 0 |
Next-hop address advertised |
IP address of local interface |
Redistribution |
Disabled |
Split horizon |
Enabled |
Configuring Basic EIGRP
- Enabling the EIGRP Feature
- Creating an EIGRP Instance
- Restarting an EIGRP Instance
- Shutting Down an EIGRP Instance
- Configuring a Passive Interface for EIGRP
- Shutting Down EIGRP on an Interface
Enabling the EIGRP Feature
You must enable the EIGRP feature before you can configure EIGRP.
Command or Action | Purpose | |
---|---|---|
Step 1 | configure terminal Example: switch# configure terminal switch(config)# |
Enters configuration mode. |
Step 2 | feature eigrp Example: switch(config)# feature eigrp |
Enables the EIGRP feature. |
Step 3 | show feature Example: switch(config)# show feature | (Optional)
Displays information about enabled features. |
Step 4 | copy running-config startup-config Example: switch(config)# copy running-config startup-config | (Optional)
Saves this configuration change. |
Use the no feature eigrp command to disable the EIGRP feature and remove all associated configuration.
Command |
Purpose |
---|---|
no feature eigrp
Example: switch(config)# no feature eigrp |
Disables the EIGRP feature and removes all associated configuration. |
Creating an EIGRP Instance
You can create an EIGRP instance and associate an interface with that instance. You assign a unique autonomous system number for this EIGRP process (see the Autonomous Systems section). Routes are not advertised or accepted from other autonomous systems unless you enable route redistribution.
Ensure that you have enabled the EIGRP feature (see the Enabling the EIGRP Feature section).
EIGRP must be able to obtain a router ID (for example, a configured loopback address) or you must configure the router ID option.
If you configure an instance tag that does not qualify as an AS number, you must configure the AS number explicitly or this EIGRP instance will remain in the shutdown state.
Command or Action | Purpose | |
---|---|---|
Step 1 | configure terminal Example: switch# configure terminal switch(config)# |
Enters configuration mode. |
Step 2 | router eigrp
instance-tag Example: switch(config)# router eigrp Test1 switch(config-router)# |
Creates a new EIGRP process with the configured instance tag. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. If you configure an instance-tag that does not qualify as an AS number, you must use the autonomous-system command to configure the AS number explicitly or this EIGRP instance will remain in the shutdown state. |
Step 3 | autonomous-system
as-number Example: switch(config-router)# autonomous-system 33 | (Optional)
Configures a unique AS number for this EIGRP instance. The range is from 1 to 65535. |
Step 4 | log-adjacency-changes Example: switch(config-router)# log-adjacency-changes | (Optional)
Generates a system message whenever an adjacency changes state. This command is enabled by default. |
Step 5 | log-neighbor-warnings [ seconds ] Example: switch(config-router)# log-neighbor-warnings |
Generates a system message whenever a neighbor warning occurs. You can configure the time between warning messages, from 1 to 65535, in seconds. The default is 10 seconds. This command is enabled by default. |
Step 6 | interface
interface-type slot/port Example: switch(config-router)# interface ethernet 1/2 switch(config-if)# |
Enters interface configuration mode. Use ? to determine the slot and port ranges. |
Step 7 | no switchport Example: switch(config-if)# no switchport |
Configures the interface as a Layer 3 routed interface. |
Step 8 | ip router eigrp
instance-tag Example: switch(config-if)# ip router eigrp Test1 |
Associates this interface with the configured EIGRP process. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 9 | copy running-config startup-config Example: switch(config)# copy running-config startup-config | (Optional)
Saves this configuration change. |
Use the no router eigrp command to remove the EIGRP process and the associated configuration.
Command |
Purpose |
---|---|
no router eigrp instance-tag
Example: switch(config)# no router eigrp Test1 |
Deletes the EIGRP process and all associated configuration. |
Note | You should also remove any EIGRP commands configured in interface mode if you remove the EIGRP process. |
This example shows how to create an EIGRP process and configure an interface for EIGRP:
switch# configure terminal switch(config)# router eigrp Test1 switch(config)# i nterface ethernet 1/2 switch(config-if)# no switchport switch(config-if)# ip router eigrp Test1 switch(config-if)# no shutdown switch(config-if)# copy running-config startup-config
For more information about other EIGRP parameters, see the Configuring Advanced EIGRP section.
Restarting an EIGRP Instance
You can restart an EIGRP instance. This clears all neighbors for the instance.
To restart an EIGRP instance and remove all associated neighbors, use the following commands:
Command |
Purpose |
---|---|
flush-routes Example:
switch(config)# flush-routes |
Flushes all EIGRP routes in the unicast RIB when this EIGRP instance restarts. |
restart eigrp instance-tag
Example: switch(config)# restart eigrp Test1 |
Restarts the EIGRP instance and removes all neighbors. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Shutting Down an EIGRP Instance
You can gracefully shut down an EIGRP instance. This action moves all routes and adjacencies but preserves the EIGRP configuration.
To disable an EIGRP instance, use the following command in router configuration mode:
Command |
Purpose |
---|---|
shutdown
Example: switch(config-router)# shutdown |
Disables this instance of EIGRP. The EIGRP router configuration remains. |
Configuring a Passive Interface for EIGRP
You can configure a passive interface for EIGRP. A passive interface does not participate in EIGRP adjacency but the network address for the interface remains in the EIGRP topology table.
To configure a passive interface for EIGRP, use the following command in interface configuration mode:
Command |
Purpose |
---|---|
ip passive-interface eigrp instance-tag |
Suppresses EIGRP hellos, which prevents neighbors from forming and sending routing updates on an EIGRP interface. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Shutting Down EIGRP on an Interface
You can gracefully shut down EIGRP on an interface. This action removes all adjacencies and stops EIGRP traffic on this interface but preserves the EIGRP configuration.
To disable EIGRP on an interface, use the following command in interface configuration mode:
Command |
Purpose |
---|---|
ip eigrp instance-tag shutdown
Example: switch(config-router)# ip eigrp Test1 shutdown |
Disables EIGRP on this interface. The EIGRP interface configuration remains. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Configuring Advanced EIGRP
This section includes the following topics:
- Configuring Authentication in EIGRP
- Configuring EIGRP Stub Routing
- Configuring a Summary Address for EIGRP
- Redistributing Routes into EIGRP
- Limiting the Number of Redistributed Routes
- Configuring Load Balancing in EIGRP
- Adjusting the Interval Between Hello Packets and the Hold Time
- Disabling Split Horizon
- Tuning EIGRP
Configuring Authentication in EIGRP
You can configure authentication between neighbors for EIGRP. See the Authentication section.
You can configure EIGRP authentication for the EIGRP process or for individual interfaces. Interface EIGRP authentication configuration overrides the EIGRP process-level authentication configuration.
Ensure that you have enabled the EIGRP feature (see the Enabling the EIGRP Feature section).
Ensure that all neighbors for an EIGRP process share the same authentication configuration, including the shared authentication key.
Create the key-chain for this authentication configuration. See the Cisco Nexus 9000 Series NX-OS Security Configuration Guide, Release 7.x.
Command or Action | Purpose | |
---|---|---|
Step 1 | configure terminal Example: switch# configure terminal switch(config)# |
Enters configuration mode. |
Step 2 | router eigrp
instance-tag Example: switch(config)# router eigrp Test1 switch(config-router)# |
Creates a new EIGRP process with the configured instance tag. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. If you configure an instance-tag that does not qualify as an AS number, you must use the autonomous-system command to configure the AS number explicitly or this EIGRP instance will remain in the shutdown state. |
Step 3 | address-family ipv4 unicast Example: switch(config-router)# address-family ipv4 unicast switch(config-router-af)# |
Enters the address-family configuration mode. This command is optional for IPv4. |
Step 4 | authentication key-chain
key-chain Example: switch(config-router-af)# authentication key-chain routeKeys |
Associates a key chain with this EIGRP process for this VRF. The key chain can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 5 | authentication mode md5 Example: switch(config-router-af)# authentication mode md5 |
Configures MD5 message digest authentication mode for this VRF. |
Step 6 | interface
interface-type slot/port Example: switch(config-router-af) interface ethernet 1/2 switch(config-if)# |
Enters interface configuration mode. Use ? to find the supported interfaces. |
Step 7 | no switchport Example: switch(config-if)# no switchport |
Configures the interface as a Layer 3 routed interface. |
Step 8 | ip router eigrp
instance-tag Example: switch(config-if)# ip router eigrp Test1 |
Associates this interface with the configured EIGRP process. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 9 | ip authentication key-chain eigrp
instance-tag key-chain Example: switch(config-if)# ip authentication key-chain eigrp Test1 routeKey |
Associates a key chain with this EIGRP process for this interface. This configuration overrides the authentication configuration set in the router VRF mode. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 10 | ip authentication mode eigrp
instance-tag
md5 Example: switch(config-if)# ip authentication mode eigrp Test1 md5 |
Configures the MD5 message digest authentication mode for this interface. This configuration overrides the authentication configuration set in the router VRF mode. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 11 | copy running-config startup-config Example: switch(config)# copy running-config startup-config | (Optional)
Saves this configuration change. |
This example shows how to configure MD5 message digest authentication for EIGRP over Ethernet interface 1/2:
switch# configure terminal switch(config)# router eigrp Test1 switch(config-router)# exit switch(config)# interface ethernet 1/2 switch(config-if)# no switchport switch(config-if)# ip router eigrp Test1 switch(config-if)# ip authentication key-chain eigrp Test1 routeKeys switch(config-if)# ip authentication mode eigrp Test1 md5 switch(config-if)# copy running-config startup-config
Configuring EIGRP Stub Routing
To configure a router for EIGRP stub routing, use the following command in address-family configuration mode:
Command |
Purpose |
---|---|
stub [ direct | receive-only | redistributed [ direct ] leak-map map-name ]
Example: switch(config-router-af)# eigrp stub redistributed |
Configures a remote router as an EIGRP stub router. The map name can be any case-sensitive, alphanumeric string up to 20 characters. |
This example shows how to configure a stub router to advertise directly connected and redistributed routes:
switch# configure terminal switch(config)# router eigrp Test1 switch(config-router)# address-family ipv4 unicast switch(config-router-af)# stub direct redistributed switch(config-router-af)# copy running-config startup-config
Use the show ip eigrp neighbor detail command to verify that a router has been configured as a stub router. The last line of the output shows the stub status of the remote or spoke router. This example shows the output from the show ip eigrp neighbor detail command:
Router# show ip eigrp neighbor detail IP-EIGRP neighbors for process 201 H Address Interface Hold Uptime SRTT RTO Q Seq Type (sec) (ms) Cnt Num 0 10.1.1.2 Se3/1 11 00:00:59 1 4500 0 7 Version 12.1/1.2, Retrans: 2, Retries: 0 Stub Peer Advertising ( CONNECTED SUMMARY) Routes
Configuring a Summary Address for EIGRP
You can configure a summary aggregate address for a specified interface. If any more specific routes are in the routing table, EIGRP will advertise the summary address out the interface with a metric equal to the minimum of all more specific routes. See the Route Summarization section.
To configure a summary aggregate address, use the following command in interface configuration mode:
Command |
Purpose |
---|---|
ip summary-address eigrp instance-tag ip-prefix/length [ distance | leak-map map-name ]
Example: switch(config-if)# ip summary-address eigrp Test1 192.0.2.0/8 |
Configures a summary aggregate address as either an IP address and network mask, or an IP prefix/length. The instance tag and map name can be any case-sensitive, alphanumeric string up to 20 characters. You can optionally configure the administrative distance for this aggregate address. The default administrative distance is 5 for aggregate addresses. |
This example causes EIGRP to summarize network 192.0.2.0 out Ethernet 1/2 only:
switch(config)# interface ethernet 1/2 switch(config-if)# no switchport switch(config-if)# ip summary-address eigrp Test1 192.0.2.0 255.255.255.0
Redistributing Routes into EIGRP
Ensure that you have enabled the EIGRP feature (see the Enabling the EIGRP Feature section).
You must configure the metric (either through the default-metric configuration option or through a route map) for routes redistributed from any other protocol.
You must create a route map to control the types of routes that are redistributed into EIGRP. See Configuring Route Policy Manager.
You can redistribute routes in EIGRP from other routing protocols.
Command or Action | Purpose | |
---|---|---|
Step 1 | configure terminal Example: switch# configure terminal switch(config)# |
Enters configuration mode. |
Step 2 | router eigrp
instance-tag Example: switch(config)# router eigrp Test1 switch(config-router)# |
Creates a new EIGRP process with the configured instance tag. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. If you configure an instance-tag that does not qualify as an AS number, you must use the autonomous-systemcommand to configure the AS number explicitly or this EIGRP instance will remain in the shutdown state. |
Step 3 | address-family ipv4 unicast Example: switch(config-router)# address-family ipv4 unicast switch(config-router-af)# |
Enters the address-family configuration mode. This command is optional for IPv4. |
Step 4 | redistribute { bgp
as | { eigrp | ospf | ospfv3 | rip } instance-tag | direct | static } route-map
name Example: switch(config-router-af)# redistribute bgp 100 route-map BGPFilter |
Injects routes from one routing domain into EIGRP. The instance tag and map name can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 5 | default-metric
bandwidth delay reliability loading mtu Example: switch(config-router-af)# default-metric 500000 30 200 1 1500 |
Sets the metrics assigned to routes learned through route redistribution. The default values are as follows:
|
Step 6 | show ip eigrp route-map statistics redistribute Example: switch(config-router-af)# show ip eigrp route-map statistics redistribute bgp |
Displays information about EIGRP route map statistics. |
Step 7 | copy running-config startup-config Example: switch(config)# copy running-config startup-config | (Optional)
Saves this configuration change. |
This example shows how to redistribute BGP into EIGRP for IPv4:
switch# configure terminal switch(config)# router eigrp Test1 switch(config-router)# redistribute bgp 100 route-map BGPFilter switch(config-router)# default-metric 500000 30 200 1 1500 switch(config-router)# copy running-config startup-config
Limiting the Number of Redistributed Routes
Route redistribution can add many routes to the EIGRP route table. You can configure a maximum limit to the number of routes accepted from external protocols. EIGRP provides the following options to configure redistributed route limits:
-
Fixed limit—Logs a message when EIGRP reaches the configured maximum. EIGRP does not accept any more redistributed routes. You can optionally configure a threshold percentage of the maximum where EIGRP will log a warning when that threshold is passed.
-
Warning only—Logs a warning only when EIGRP reaches the maximum. EIGRP continues to accept redistributed routes.
-
Withdraw—Start the timeout period when EIGRP reaches the maximum. After the timeout period, EIGRP requests all redistributed routes if the current number of redistributed routes is less than the maximum limit. If the current number of redistributed routes is at the maximum limit, EIGRP withdraws all redistributed routes. You must clear this condition before EIGRP accepts more redistributed routes. You can optionally configure the timeout period.
Be sure the EIGRP feature is enabled (see the Enabling the EIGRP Feature section).
Command or Action | Purpose | |
---|---|---|
Step 1 | configure terminal Example: switch# configure terminal switch(config)# |
Enters configuration mode. |
Step 2 | router eigrp
instance-tag Example: switch(config)# router eigrp Test1 switch(config-router)# |
Creates a new EIGRP process with the configured instance tag. |
Step 3 | redistribute { bgp
id | direct | eigrp
id | ospf
id | rip
id | static } route-map
map-name Example: switch(config-router)# redistribute bgp route-map FilterExternalBGP |
Redistributes the selected protocol into EIGRP through the configured route map. |
Step 4 | redistribute maximum-prefix
max [ threshold ] [ warning-only | withdraw [ num-retries timeout ]] Example: switch(config-router)# redistribute maximum-prefix 1000 75 warning-only |
Specifies a maximum number of prefixes that EIGRP will distribute. The range is from 0 to 65536. Optionally specifies the following:
|
Step 5 | show running-config eigrp Example: switch(config-router)# show running-config eigrp | (Optional)
Displays the EIGRP configuration. |
Step 6 | copy running-config startup-config Example: switch(config)# copy running-config startup-config | (Optional)
Saves this configuration change. |
This example shows how to limit the number of redistributed routes into EIGRP:
switch# configure terminal switch(config)# router eigrp Test1 switch(config-router)# redistribute bgp route-map FilterExternalBGP switch(config-router)# redistribute maximum-prefix 1000 75
Configuring Load Balancing in EIGRP
You can configure load balancing in EIGRP. You can configure the number of Equal Cost Multiple Path (ECMP) routes using the maximum paths option.
Ensure that you have enabled the EIGRP feature (see the Enabling the EIGRP Feature section).
Command or Action | Purpose | |
---|---|---|
Step 1 | configure terminal Example: switch# configure terminal switch(config)# |
Enters configuration mode. |
Step 2 | router eigrp
instance-tag Example: switch(config)# router eigrp Test1 switch(config-router)# |
Creates a new EIGRP process with the configured instance tag. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. If you configure an instance-tag that does not qualify as an AS number, you must use the autonomous-system command to configure the AS number explicitly or this EIGRP instance will remain in the shutdown state. |
Step 3 | address-family ipv4 unicast Example: switch(config-router)# address-family ipv4 unicast switch(config-router-af)# |
Enters the address-family configuration mode. This command is optional for IPv4. |
Step 4 | maximum-paths
num-paths Example: switch(config-router-af)# maximum-paths 5 |
Sets the number of equal cost paths that EIGRP will accept in the route table. The range is from 1 to 16. The default is 8. |
Step 5 | copy running-config startup-config Example: switch(config)# copy running-config startup-config | (Optional)
Saves this configuration change. |
This example shows how to configure equal cost load balancing for EIGRP over IPv4 with a maximum of six equal cost paths:
switch# configure terminal switch(config)# router eigrp Test1 switch(config-router)# maximum-paths 6 switch(config-router)# copy running-config startup-config
Adjusting the Interval Between Hello Packets and the Hold Time
You can adjust the interval between hello messages and the hold time.
By default, hello messages are sent every 5 seconds. The hold time is advertised in hello messages and indicates to neighbors the length of time that they should consider the sender valid. The default hold time is three times the hello interval, or 15 seconds.
To change the interval between hello packets, use the following command in interface configuration mode:
Command |
Purpose |
---|---|
ip hello-interval eigrp instance-tag seconds
Example: switch(config-if)# ip hello-interval eigrp Test1 30 |
Configures the hello interval for an EIGRP routing process. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. The range is from 1 to 65535 seconds. The default is 5. |
On very congested and large networks, the default hold time might not be sufficient time for all routers to receive hello packets from their neighbors. In this case, you might want to increase the hold time.
To change the hold time, use the following command in interface configuration mode:
Command |
Purpose |
---|---|
ip hold-time eigrp instance-tag seconds
Example: switch(config-if)# ip hold-time eigrp Test1 30 |
Configures the hold time for an EIGRP routing process. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. The range is from 1 to 65535. |
Use the show ip eigrp interface detail command to verify timer configuration.
Disabling Split Horizon
You can use split horizon to block route information from being advertised by a router out of any interface from which that information originated. Split horizon usually optimizes communications among multiple routing switches, particularly when links are broken.
By default, split horizon is enabled on all interfaces.
To disable split horizon, use the following command in interface configuration mode:
Command |
Purpose |
---|---|
no ip split-horizon eigrp instance-tag
Example: switch(config-if)# no ip split-horizon eigrp Test1 |
Disables split horizon. |
Tuning EIGRP
You can configure optional parameters to tune EIGRP for your network.
You can configure the following optional parameters in address-family configuration mode:
Command |
Purpose |
---|---|
default-information originate [ always | route-map map-name ] Example: switch(config-router-af)# default-information originate always |
Originates or accepts the default route with prefix 0.0.0.0/0. When a route map is supplied, the default route is originated only when the route map yields a true condition. The map name can be any case-sensitive, alphanumeric string up to 20 characters. |
distance internal external
Example : switch(config-router-af)# distance 25 100 |
Configures the administrative distance for this EIGRP process. The range is from 1 to 255. The internal value sets the distance for routes learned from within the same autonomous system (the default value is 90). The external value sets the distance for routes learned from an external autonomous system (the default value is 170). |
metric maximum-hops hop-count Example: switch(config-router-af)# metric maximum-hops 70 |
Sets maximum allowed hops for an advertised route. Routes over this maximum are advertised as unreachable. The range is from 1 to 255. The default is 100. |
metric weights tos k1 k2 k3 k4 k5 Example: switch(config-router-af)# metric weights 0 1 3 2 1 0 |
Adjusts the EIGRP metric or K value. EIGRP uses the following formula to determine the total metric to the network: metric = [k1*bandwidth + (k2*bandwidth)/(256 – load) + k3*delay] * [k5/(reliability + k4)] Default values and ranges are as follows:
|
timers active-time { time-limit | disabled }
Example : switch(config-router-af)# timers active-time 200 |
Sets the time the router waits in minutes (after sending a query) before declaring the route to be stuck in the active (SIA) state. The range is from 1 to 65535. The default is 3. |
You can configure the following optional parameters in interface configuration mode:
Command |
Purpose |
---|---|
ip bandwidth eigrp instance-tag bandwidth
Example: switch(config-if)# ip bandwidth eigrp Test1 30000 |
Configures the bandwidth metric for EIGRP on an interface. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. The bandwidth range is from 1 to 2,560,000,000 Kb/s. |
ip bandwidth-percent eigrp instance-tag percent
Example: switch(config-if)# ip bandwidth-percent eigrp Test1 30 |
Configures the percentage of bandwidth that EIGRP might use on an interface. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. The percent range is from 0 to 100. The default is 50. |
no ip delay eigrp instance-tag delay
Example: switch(config-if)# ip delay eigrp Test1 100 |
Configures the delay metric for EIGRP on an interface. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. The delay range is from 1 to 16777215 (in tens of microseconds). |
ip distribute-list eigrp instance-tag { prefix-list name | route-map name} { in | out }
Example: switch(config-if)# ip distribute-list eigrp Test1 route-map EigrpTest in |
Configures the route filtering policy for EIGRP on this interface. The instance tag, prefix list name, and route map name can be any case-sensitive, alphanumeric string up to 20 characters. |
no ip next-hop-self eigrp instance-tag
Example: switch(config-if)# ip next-hop-self eigrp Test1 |
Configures EIGRP to use the received next-hop address rather than the address for this interface. The default is to use the IP address of this interface for the next-hop address. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
ip offset-list eigrp instance-tag { prefix-list name | route-map name} { in | out } offset
Example: switch(config-if)# ip offfset-list eigrp Test1 prefix-list EigrpList in |
Adds an offset to incoming and outgoing metrics to routes learned by EIGRP. The instance tag, prefix list name, and route map name can be any case-sensitive, alphanumeric string up to 20 characters. |
ip passive-interface eigrp instance-tag
Example: switch(config-if)# ip passive-interface eigrp Test1 |
Suppresses EIGRP hellos, which prevents neighbors from forming and sending routing updates on an EIGRP interface. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Configuring Virtualization for EIGRP
You can create multiple VRFs and use the same or multiple EIGRP processes in each VRF. You assign an interface to a VRF.
Note | Configure all other parameters for an interface after you configure the VRF for an interface. Configuring a VRF for an interface deletes all other configuration for that interface. |
Ensure that you have enabled the EIGRP feature (see the Enabling the EIGRP Feature section).
Command or Action | Purpose | |
---|---|---|
Step 1 | configure terminal Example: switch# configure terminal switch(config)# |
Enters configuration mode. |
Step 2 | vrf context
vrf-name Example: switch(config)# vrf context RemoteOfficeVRF switch(config-vrf)# |
Creates a new VRF and enters VRF configuration mode. The VRN name can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 3 | router eigrp
instance-tag Example: switch(config)# router eigrp Test1 switch(config-router)# |
Creates a new EIGRP process with the configured instance tag. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. If you configure an instance-tag that does not qualify as an AS number, you must use the autonomous-systemcommand to configure the AS number explicitly or this EIGRP instance will remain in the shutdown state. |
Step 4 | interface ethernet slot/port Example: switch(config)# interface ethernet 1/2 switch(config-if)# |
Enters interface configuration mode. Use ? to find the slot and port ranges. |
Step 5 | no switchport Example: switch(config-if)# no switchport |
Configures the interface as a Layer 3 routed interface. |
Step 6 | vrf member
vrf-name Example: switch(config-if)# vrf member RemoteOfficeVRF |
Adds this interface to a VRF. The VRF name can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 7 | ip router eigrp
instance-tag Example: switch(config-if)# ip router eigrp Test1 |
Adds this interface to the EIGRP process. The instance tag can be any case-sensitive, alphanumeric string up to 20 characters. |
Step 8 | copy running-config startup-config Example: switch(config)# copy running-config startup-config | (Optional)
Saves this configuration change. |
This example shows how to create a VRF and add an interface to the VRF:
switch# configure terminal switch(config)# vrf context NewVRF switch(config-vrf)# router eigrp Test1 switch(config-router)# i nterface ethernet 1/2 switch(config-if)# no switchport switch(config-if)# ip router eigrp Test1 switch(config-if)# vrf member NewVRF switch(config-if)# copy running-config startup-config
Verifying the EIGRP Configuration
To display the EIGRP configuration information, perform one of the following tasks:
Command |
Purpose |
---|---|
show ip eigrp [ instance-tag ] |
Displays a summary of the configured EIGRP processes. |
show ip eigrp [ instance-tag ] interfaces [ type number ] [ brief ] [ detail ] |
Displays information about all configured EIGRP interfaces. |
show ip eigrp instance-tag neighbors [ type number ] |
Displays information about all the EIGRP neighbors. Use this command to verify the EIGRP neighbor configuration. |
show ip eigrp [ instance-tag ] route [ ip-prefix/length ] [ active ] [ all-links ] [detail-links] [ pending ] [ summary ] [ zero-successors ] [ vrf vrf-name ] |
Displays information about all the EIGRP routes. |
show ip eigrp [ instance-tag ] topology [ ip-prefix/length ] [ active ] [ all-links ] [detail-links] [ pending ] [ summary ] [ zero-successors ] [ vrf vrf-name ] |
Displays information about the EIGRP topology table. |
show running-configuration eigrp |
Displays the current running EIGRP configuration. |
Displaying EIGRP Statistics
To display EIGRP statistics, use the following commands:
Command |
Purpose |
---|---|
show ip eigrp [ instance-tag ] accounting [ vrf vrf-name ] |
Displays accounting statistics for EIGRP. |
show ip eigrp [ instance-tag ] route-map statistics redistribute |
Displays redistribution statistics for EIGRP. |
show ip eigrp [ instance-tag ] traffic [ vrf vrf-name ] |
Displays traffic statistics for EIGRP. |
Configuration Examples for EIGRP
This example shows how to configure EIGRP:
feature eigrp interface ethernet 1/2 no switchport ip address 192.0.2.55/24 ip router eigrp Test1 no shutdown router eigrp Test1 router-id 192.0.2.1
Related Topics
See Configuring Route Policy Manager for more information on route maps.
Additional References
For additional information related to implementing EIGRP, see the following sections:
Related Documents
Related Topic |
Document Title |
---|---|
EIGRP CLI commands |
|
Introduction to EIGRP Tech Note |
|
http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a008012dac4.shtml |
EIGRP Frequently Asked Questions |
MIBs
MIBs |
MIBs Link |
---|---|
CISCO-EIGRP-MIB |
To locate and download MIBs, go to the following: MIB Locator. |
Feature History for EIGRP
Table below lists the release history for this feature.
Feature Name |
Releases |
Feature Information |
---|---|---|
EIGRP |
5.0(3)A1(1) |
This feature was introduced. |