Network services problem.

[Farooq Muhammad]

Hi all,

I am facing a strange problem in the network .Just want to know which way to move forward now as i have tried a number of steps but found no clue up till now.

The network topology is shown in the attached pic.The DC is composed of Cisco 6500 Core in VSS attached to a number of access switches for the campus users.There is a Nexus 5K to which a number of Virtual and physical servers are attached .The core is attached to two ASR 10002 routers with trunks and port channels on the ASR side of config.There is another ISR 2900 router attached to the same core switch.All three routers and core running ospf in single areo 0. The interface vlan 2 is used on the Core switch to build ospf relation with the other three routers.

Now the problem is periodically the remote branches attached to the ASRs are unable to ping the servers and the in-campus users are accessing the services normally.When i further troubleshoot i came to know that when the problem hits the ASR routers itself are unable to ping the servers i-e 10.1.15.x but at the same time the campus users and ISR 2900 users are able to ping them and get services.

The strange thing is , during the problem i can ping all the SVIs configured on the core switch from both ASR and similarly i can ping all the servers from the Core switch with the source of the ping to be any interface of the Core.

During this activity i haven't seen any status change of port/ interface , ospf related messages, mac flaping etc nothing seems abnormal in syslogs.

anyone please suggest a possible clue.

one thing remains is Packet capture on the devices.

[Richard Burts]

The symptoms you describe are puzzling. To be sure that I have a correct understanding - when the issue is going on, from the ASR you are able to ping the AVI to which the servers connect but not able to ping the servers. And at this time the 2900 is able to ping the servers without issue?

Perhaps some details of the configuration might allow us to get a better understanding of what is going on?

HTH

Rick

[Farooq Muhammad]

Hi ,

Sorry for the late reply ,the problem was solved the next day. Actually there was layer three ether-channel on the ASR and layer two trunks on the 6500 core switch.

Regards.

[Richard Burts]

Thank you for posting back to the forum and letting us know that the problem was resolved. It is helpful to be able to relate description of a problem with the explanation of what turned out to be the real problem.

HTH

Rick