eigrp with many subinterfaces

[reaven1]

Hi i am confused on how to proceed, I have a catalyst 6509 which is running eigrp with more than a 100 SubInterfaces connected to a provider servicing mpls for the external clients. 

I am trying slowly migrate over to a catalyst 9600 which is for the time being connected trunk directly to the 6509. After configuring all the SubInterfaces and connect the provider to the 9600 it doesn't work, maybe because the eigrp config is on the 6509. Can i config the 9600 eigrp with the same AS and the same config as the 6509 which is 

router eigrp 5001
 redistribute static
 network 10.0.0.0
 no auto-summary
 no eigrp log-neighbor-changes
!

[Torbjørn]

That configuration would be valid for a 9600 and enable EIGRP on all interfaces with addresses within 10.0.0.0/8. Using the same ASN as the neighbor device is fine and is in fact a requirement for EIGRP.

Is there currently no EIGRP configuration at all on the 9600? If so that would explain why routing isn't working as intended. If you intend to move the peering for one and one interface over from the 6509 to the 9600 you can do the following:

1: Ensure that the interfaces are up and working and can reach the neighbor IP address(addresses of the ISP device subinterfaces)

2: Configure EIGRP on the 9600 without the network command(the configuration you supplied above is fine, minus the network command)

3: Match the interface you intend to bring the peering up on with a network command under EIGRP configuration.

4: Verify that the EIGRP adjacency comes up

5: Shut the corresponding sub-interface on the 6509

[reaven1]

that makes sense, I just wasnt sure if I added the config on the 9600 will bring the whole thing down.

Confused on the step 2 and 3, I dont add the network command on the 9600 but on the step 3 I add it ?

[Torbjørn]

The network command enables EIGRP on the interface with the matching network.

If your goal is to do a slow cut-over from the 6509 to the 9600 you will want to do one/a few interfaces at a time. So if the first link-net/interface you want to migrate has an IP address of 10.0.1.1/29 your EIGRP config on the 9600 will look like this when enabling eigrp for the first link:

router eigrp 5001
 redistribute static
 network 10.0.1.0 0.0.0.7 ! Matches the exact subnet of the link net
 no auto-summary
 no eigrp log-neighbor-changes
!

Alternatively you can shut all the subinterfaces of the 9600 and enter the network 10.0.0.0 command from the start, then bring up interfaces one by one on the 9600 to bring up the neighbor adjacencies. When you shut the corresponding interface on the 6509 you will be left with only an eigrp neighborship between your new router and the ISP.

You should also ensure that you have a routing-protocol up and running between the 6509 and the 9600 if you are taking this approach such that they share a common routing domain. You can achieve this by first setting up a link-net between the 9600 and the 6509 and enabling eigrp for the interface on both ends using a network statement as described above.

As others have pointed out you should ensure that the router-id isn't the same for the 6509 and the 9600. A duplicate router-id will not affect regular eigrp routes, but the redistributed static routes will not be accepted if the router-id of the originating router is identical to the local rid. This can be configured statically with eigrp router-id (IP address).

I recommend taking a look at the eigrp configuration guide for ios-xe for the configuration specifics: https://www.cisco.com/c/en/us/td/docs/routers/ios/config/17-x/ip-routing/b-ip-routing/m_ire-enhanced-igrp.html

[M02@rt37]

Hello @reaven1,

Configuring the C9600 with EIGRP using the same AS and similar settings, you should be able to seamlessly migrate your network.

If your provider is directly connected to the C9600, and you need to establish an EIGRP neighborship with them, you should indeed configure the network command for the specific interface on the C9600 that connects to the provider. This command tells EIGRP which interfaces to participate in the EIGRP process.

[David Ruess]

Hello,

Since you are configuring a 1:1 switchover does that also mean the RID. If the RIDs are the same and they are both connected then it could cause issues where you aren't learning routes. 

Are you getting an EIGRP neighborship?

-David

[reaven1]

the new switch(9600) its connected trunk to the 6509 in which eigrp and everything else is in production and working.

What I want as testing is connect the provider from the 6509 to the 9600 which its already configured with the subinterfaces but was missing the eigrp config but wasnt sure if having the same eigrp config in both routers conneced one to the other will cause an issue i dont think shutting down the parent int in the 6509 will do anything since it wont have any cable connected.

i havent done the test yet to know if i can see the neighbors or you mean between the 6509  and 9600 ?

[David Ruess]

If they have the same config then yes it could cause issues, especially with the same RID and networks configured. You may need to schedule a Service Interruption and test it out by swinging the Provider port over to see if you establish neighborship. Some providers need the new MAC address of what's connecting to them in order to allow it on the port. as far as the neighborship I meant between the new 9600 and the provider.

-David

[molaa6255]

I've configured EIGRP with the same AS number (e.g., AS 5001) as my existing 6509, replicated the network statements, and established trunk connections between the switches. I'm experiencing routing issues, with EIGRP not forming neighbor relationships properly, and my new switch is not learning the expected routes from the older Catalyst 6509. This situation would prompt me to seek advice and assistance from the Cisco community to troubleshoot and resolve the EIGRP peering and routing problems, ensuring a successful migration to the Catalyst 9600.

[Richard Pidcock]

I think some of the folks on this thread have hit the key points. 

1.  Establish EIGRP neighborship with provider
2.  Network command for your network between you and provider.
3.  As you are ready to transition you could move one subinterface at a time; shut the subinterface on the old device, bring up the corresponding subinterface on the new device, then advertise the appropriate subnet with the appropriate network command.

4.  Alternatively, you can move all subinterfaces at the same time, shut the old subinterfaces, bring up the new subinterfaces, then advertise the 10.0.0.0/8 network command (assuming all your subinterfaces are in 10.0.0.0/8)

[reaven1]

waiting for the maintenance window tonight

[reaven1]

Last night I did the test, even though I established neighborship it was only from the 9600, i could ping and telnet to the clients routers from the 9606 but thats it.

I dont have access from nor to the 6509 and by consequence the client dont have access to any resource on the network.

I am missing something in the connection between the 6509 and the 9600

[Richard Pidcock]

Can you share a topology diagram?

[reaven1]

[MHM Cisco World]

eigrp the AS is important to be match between two Peers. 
here 
6500 with subinterface have EIGRP AS 5001 

the 9500 must have same AS 5001 to connect to Edge routes and start advertise the EIGRP prefix. 
can you check the

show ip egirp neighbor (share here)

Thanks A Lot
MHM