EIGRP Named Mode Configuration

lagapidis · September 5, 2018, 3:47pm

Hello Vinod

The main differences between named and classic modes are the way in which they are implemented (globally for named while both globally and in interface mode for classic) as well as the addition of a sixth K value for the metric.

On the back end, that is, concerning the way that the routers interpret and operate in EIGRP, very little has changed. So a named mode EIGRP router can communicate with a classic EIGRP router. Since you configure the AS number under the EIGRP name configuration, if the AS is the same, they will communicate.

Now the only restriction is the issue with the K values. In order for EIGRP named and classic to interoperate, the number of K values must be the same. There are two possibilities.

One is that the classic EIGRP is being run on an older version of IOS which supports 5 K values. Named EIGRP configured router that receives EIGRP packets with 5 K values will revert to functioning with 5 K values and will not advertise the sixth.

The other possibility is that classic EIGRP is configured on a newer IOS version will actually advertise a sixth K value, but will not have it participate in the metric calculation. This is why you may see a K6 value in a wireshark capture of an EIGRP exchange. This will allow classic EIGRP to successfully interface with a named EIGRP configured router, without actually using that 6th K value for the metric.

I hope this has been helpful!

Laz

networkeh · January 2, 2019, 7:11pm

Hello,
I tested EIGRP named mode in GNS3 with both Dynamips and IOSv. It seems in named mode metric calculation varies from the classic mode. Even the metric calculation in the topology table is not the one in the routing table. Does anyone know the reason please? Thank you.

L0: 10.1.1.1 --R1—192.168.12.0—R2

R1#sho int l0 | inc DLY
  MTU 1514 bytes, BW 8000000 Kbit/sec, DLY 5000 usec,

R2#sho int g0/0 | inc DLY
  MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,

R2#sho ip route 10.1.1.0
Routing entry for 10.1.1.0/24
  Known via "eigrp 100", distance 90, metric 10880, type internal
  Redistributing via eigrp 100
  Last update from 192.168.12.1 on GigabitEthernet0/0, 00:04:48 ago
  Routing Descriptor Blocks:
  * 192.168.12.1, from 192.168.12.1, 00:04:48 ago, via GigabitEthernet0/0
      Route metric is 10880, traffic share count is 1
      Total delay is 12 microseconds, minimum bandwidth is 1000000 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 1

lagapidis · January 3, 2019, 5:34pm

Hello Network

EIGRP named mode supports what is known as the Wide Metrics feature. This feature supports 64-bit metric calculations as opposed to EIGRP classic mode that use 32-bit calculations. This results in varying metric values between the two.

Wide metrics was introduced in order to accommodate high-bandwidth interfaces and Ethernet channels. The increase in available speeds has resulted in incorrect or inconsistent routing behavior with the classic EIGRP routing metrics. The lowest delay that can be configured for an interface is 10 microseconds. As a result, interfaces with speeds of 10 Gbps or more including channeld interfaces will appear to EIGRP as a single GE interface. For this reason, the 64 bit metric calculation has been introduced resulting in different metric values. More on this can be found here:

The new 64 bit metric calculations are designed to be backward compatible with classic EIGRP. However, sometimes scaling can be an issue. More on this can be found below.

I hope this has been helpful!

Laz

syncope988 · February 1, 2019, 7:07am

Hi Rene and staff

i just look at EIGRP named to configure a lab in another lesson
So i explore the commands of the configuration modes; in the labs i did, i only used the topology mode base

I tried to test (just for fun) the command with EIGRP that i suppose to set Multi-Topology Routing

As you see, IOS answer “VIDEO does not exist”
Could you give me some explanation where i can set a topology that is not the topology base ?
Thanks

lagapidis · February 4, 2019, 11:11am

Hello Dominique

In order to specify a topology other than base, you must define it first. As the following Cisco documentation states:

The topology must be defined globally with the global-address-family command in global address-family configuration mode before the topology can be configured under the EIGRP process.

Now how do you do that? Well, here’s an example:

 Router(config)# global-address-family ipv4 
 Router(config-af)# topology VIDEO
 Router(config-af-topology)# all-interfaces 
 Router(config-af-topology)# end

You can find out more about this command here:

https://www.cisco.com/c/en/us/td/docs/ios/mtr/command/reference/mtr_book/mtr_01.html#wp1065797

I hope this has been helpful!

Laz

syncope988 · February 5, 2019, 4:45am

thank you very much Laz,

After setting topology VIDEO under global-address-family, i went (just) a little further to explore the commands of the cisco doc example

This is what i got

Surprisingly i did not get the network command under ‘config-router-af-topology’

I used this version of IOS in a GNS3 lab

So, and sorry about that, that takes me to a new question: in my example, how to activate the interfaces of the topology VIDEO for EIGRP ?
Thanks

lagapidis · February 11, 2019, 7:54am

Hello Dominique

The example provided from the link I sent you that you attempted is found in the Cisco IOS IP Routing: EIGRP Command Reference document. This is a general overview document providing commands that are common to multiple platforms and IOS versions. Because various IOS versions may deal with commands differently, there is always the possibility that some differences may appear in such documents.

Viewing documents that are more specific to the topics in question, we can get a more accurate view of the commands and how they function. This is the case for this situation. If you look at the following link from Cisco’s “Multitopology Routing Configuration Guide, Cisco IOS Release 15S” document, you will find that the commands are slightly different.

Here you are told to configure the network command outside of the VOICE topology configuration mode. But, you can specify which topology is being used on a per interface basis as shown in the link below:

Try experimenting with these variations in the commands and I believe that you will find the solution that matches your IOS version.

I hope this has been helpful!

Laz

narad · July 2, 2021, 7:50pm

what is multi topology routing in named mode ?

Classic EIGRP support IPv6 or not ?

lagapidis · July 19, 2021, 4:43am

Hello Narad

Multi-Topology Routing is a feature of Cisco IOS routers that allows them to define multiple topologies within a network. Each topology is essentially a subset of the routers and links in a network. MTR allows a separate set of routes to be calculated for each topology.

This can be configured for any routing protocol including OSPF, BGP, IS-IS, as well as EIGRP. This is not a feature specific to named mode of EIGRP. You can find out more information about MTR at the following Cisco documentation:

You can also find EIGRP-specific info about the feature here:

When you say “classic” I assume you mean not named mode EIGRP, correct? Yes, EIGRP does support IPv6 as long as the IOS being used supports IPv6. To be sure, make sure you check out the available features of the IOS in the Cisco Feature Navigator. As far as I know, all 15.X versions of IOS support IPv6 for EIGRP.

I hope this has been helpful!

Laz

jandtay23 · October 30, 2021, 5:25pm

Hey there Network Lessons crew,

This lesson says that EIGRP Named Mode Configuration is a “new method of configuration”. What I’m curious about is: is this method of configuration considered preferred/best practice? I can certainly appreciate the convenience of interface level commands being done in the same spot, but I wasn’t sure if out in the wider world I’d get flak for configuring “classic” EIGRP. Thanks!

lagapidis · November 2, 2021, 10:51am

Hello Joel

Currently, both the “classic” as well as the “new” named mode configuration options are considered to be valid and equally acceptable. Unless there is some kind of organizational policy or company policy that says otherwise, no one will give you any trouble from a “best practice” point of view if you configure classic EIGRP.

It’s good to keep in mind that in the long run, when Cisco makes such changes to the way that features are configured, it is usually (but not always) an indication that the “old” way will eventually be phased out. When and if that will happen in this case remains to be seen.

I hope this has been helpful!

Laz

meran70 · March 24, 2022, 10:37pm

Hi Rene,
Im trying redistribute EIGRP named mode into BGP
but it doesnt work when I trying to type under BGP router configuratuon:
router bgp 1005
redistribute eigrp …only numbers possible

lagapidis · March 29, 2022, 4:43am

Hello Mehran

EIGRP named mode does not do away with the autonomous system numbers used by EIGRP. Under the address-family configuration, you must still specify an autonomous system number for the specific EIGRP domain. It is this autonomous system number that you must use when redistributing.

Note that EIGRP named mode may use a virtual instance name instead of a number, but it does not replace the AS. The AS is specified under the address-family command. Note the named EIGRP configuration of R1 from the lesson:

router eigrp MY_NAME
 !
 address-family ipv4 unicast autonomous-system 12
  !
  af-interface GigabitEthernet0/0
   authentication mode md5
   authentication key-chain MY_CHAIN
  exit-af-interface

In this scenario, if you were to redistribute from EIGRP to BGP, the autonomous system number you would use is 12.

I hope this has been helpful!

Laz