EIGRP Routing ISSUE

[Abbas Ravat]

Dear Colleagues

I have some issue as some application does not work or very slow (Like cisco anyconnect show message "failed to launch downloader"). scenario is like below.

I have Cisco 3750 Floor Sw (Stack of 3 Switch), Have Two Eigrp Uplink to N7K-1 and N7K-2 (below is the configuration).

3750 Switch Configuration

interface TenGigabitEthernet1/1/1
description L3-Link to KPC-NX7K9-SOUTH-DC-SW1(Ten5/1)
no switchport
ip address 192.168.102.42 255.255.255.252
ip authentication mode eigrp 100 md5
ip authentication key-chain eigrp 100 eigrppwd

interface TenGigabitEthernet3/1/1
description L3-Link to KPC-NX7K9-NORTH-DC-SW1(Ten5/1)
no switchport
ip address 192.168.101.42 255.255.255.252
ip authentication mode eigrp 100 md5
ip authentication key-chain eigrp 100 eigrppwd

N7K-1 configuration

interface Eth 5/10
no switchport
ip address 192.168.102.42 255.255.255.252
ip authentication mode eigrp 100 md5
ip authentication key-chain eigrp 100 eigrppwd

N7K-2 Configuration

interface Eth 5/10
no switchport
ip address 192.168.101.42 255.255.255.252
ip authentication mode eigrp 100 md5
ip authentication key-chain eigrp 100 eigrppwd

I Ping ISE IP and see frequent drop then did tracroute the ISE IP and shutdown the link from N7K-1 (ISE traceroute was going from this link) and after that everything was stable and anyconnect also worked without any issue.

Please anyone can guide or advice what could be the issue with EIGRP?

Thanks in Advanced.

[Deepak Kumar]

Hi,

I hope both switches are in the VPC. What is the nexus version? Is EIGRP neighborship flapping?

Starting with NX-OS 7.3, vPC domain configuration supports the layer3 peer-router command. There is a big change in the EIGRP TTL value. It is set 1 in the new codes. It might cause an issue of neighborship flapping and unstable network.

[balaji.bandi]

 how can you have duplicate IP address point to point links ? or am I reading wrong?

3750 Switch Configuration

interface TenGigabitEthernet1/1/1
description L3-Link to KPC-NX7K9-SOUTH-DC-SW1(Ten5/1)
no switchport
ip address 192.168.102.42 255.255.255.252
ip authentication mode eigrp 100 md5
ip authentication key-chain eigrp 100 eigrppwd

interface TenGigabitEthernet3/1/1
description L3-Link to KPC-NX7K9-NORTH-DC-SW1(Ten5/1)
no switchport
ip address 192.168.101.42 255.255.255.252
ip authentication mode eigrp 100 md5
ip authentication key-chain eigrp 100 eigrppwd

N7K-1 configuration

interface Eth 5/10
no switchport
ip address 192.168.102.42 255.255.255.252
ip authentication mode eigrp 100 md5
ip authentication key-chain eigrp 100 eigrppwd

N7K-2 Configuration

interface Eth 5/10
no switchport
ip address 192.168.101.42 255.255.255.252
ip authentication mode eigrp 100 md5
ip authentication key-chain eigrp 100 eigrppwd