Problems with running EIGRP as PE-CE routing protocol 2

[vanoporchkhidze]

Dear all,

I am facing with the exact problem as a previous user of running EIGRP as the PE-CE routing protocol for a MPLS VPN customer, but in different hardware.  The PE router is a 7609-S RSP720-3CXL-GE  running IOS 12.2(33)SRC3.

(When I have 33 prefixes or more in the VRF table on the PE, and I try to advertise this network to the CE router (by redistributing BGP into EIGRP), the EIGRP process begins to flap.

I can't advertise prefix more that 32 subnets at a time why?????

The very weird part here, is that when I do debug ip eigrp on the PE and the CE, I can see that the PE router is sending the routes to the CE, but on the CE I can see nothing.)

In my case there is 16 prefixes. When redistributing BGP into EIGRP on allready adjasent EIGRP neighbors everything works perfect, until some side clears it then it begans flaping. On PE router debug is show "retry limit exceeded" ,on CE  "Interface Goodbye received"

If solution will be same what software should I use?

Thanks,

George Shiukashvili

[Mahesh Gohil · Accepted solution]

Hello George,

Are you able to ping PE-CE with higher packet size (1400,1500 or 1600). If so can you check for any interface errors on interface

The debug output indicate that eigrp did not receive any ack. from  peer. As a handy solution can you try to change ip mtu 1500 on interface at both

end

Regards

mahesh

[vanoporchkhidze]

Dear mahesh,

Neither packet loss nor errors, when pinging customer with mtu 1500, df-bit is set. MTU is set on both sides 1500

Best regards

George

[Peter Paluch · Accepted solution]

George,

Let me ask a few questions:

1. What is the link layer technology that interconnects the PE and CE that are currently experiencing these issues?
2. Are there any devices inside the PE-CE path that could at least possibly (and randomly) block multicasts and/or large packets?
3. Is it possible to modify the EIGRP configuration both on PE and CE to manual neighbor definition using the neighbor commands? This would force all EIGRP comunication between the PE and CE to run as unicast, possibly avoiding some issues with multicast packet delivery.
4. Is it possible for you to post some show commands from both the PE and CE? I would be interested in seeing the show ip interface, show interfaces, show running-config interface regarding the particular interfaces on PE and CE that connect to each other, and also, I would like to see the EIGRP configuration on both devices.

I agree with the assessment of Mahesh - the preliminary information we have suggest that either the PE packets are not arriving at the CE, or the ACK packets from CE are not arriving back at the PE. Your own debug analysis furthermore revealed that there are no EIGRP Update packets arriving from the PE at the CE. Problems with MTU could indeed cause these problems but it is necessary to inspect the entire path between PE and CE.

Best regards,

Peter

[vanoporchkhidze]

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Dear all

There was really MTU issue on PE router.

Thanks

[eicc30000]

Could you please share which mtu was causing your issue? is it ip mtu ? or interface/mpls