Asymmetrical routing issue

[caijunjie]

Hi all

May i know how do i know if issue (symtoms) in network is due to Asymmetrical routing ?

How do I use trceroute to test for Asymmetrical routing.

Please help

[Steve Lyons]

To determine if you have asymmetric routing you will need to use trace route from the source to destination and then from the destination back to the source. If the information provided by trace route shows the packets are traversing different routers then you have asymmetric routing.

Steve Lyons - Cisco

[caijunjie]

Hi Steve

Thanks for the quick reply. Can I say that when i trace from A --> B, i get a sequence of 5 hops for example, than i trace from

B --> A, it would be also the same 5 hops but reverse in sequence if asymmetric routing is not present?

Thanks in advance

[sundar.palaniappan]

Use extended ping and set the 'record' option and it would record the path the echo packet took to get the destination and would also show the hops on the return path.

This is a very useful tool in identifying asymmetric routing.

Have a look at this link.

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f22.shtml#extend_ping

HTH

Sundar