09-02-2010 06:19 AM - edited 03-04-2019 09:38 AM
Switches learn which ports connect to which MAC addresses, and direct traffic to them accordingly.
Is there a routing protocol/config/algorithm which learns which interface connects to a specified subnet by seeing a source IP from that subnet? And if an IP from the subnet later appears on a different interface, it redirects traffic to that subnet?
Thanks!
Paul
09-02-2010 06:50 AM
Hello Paul,
>> Is there a routing protocol/config/algorithm which learns which interface connects to a specified subnet by seeing a source IP from that subnet? And if an IP from the subnet later appears on a different interface, it redirects traffic to that subnet?
no as far as I know as a router has to modify packets in order to route ( change TTL and recalculate header checksum and rewrite with appropriate L2 information) and does not simply forward frames between ports.
Hope to help
Giuseppe
09-02-2010 07:25 AM
Paul, Giuseppe,
There actually is an arcane functionality called IOS Local-Area Mobility which uses ARP packets sent by stations to populate routing tables (!) on routers by host routes towards these stations, essentially allowing a station to freely move throughout the campus. Quite a crude solution but it works. Nevertheless, it is not a protocol, merely a proprietary logic implemented in IOS that uses information contained in ARP messages.
Read more at this URL:
http://www.cisco.com/en/US/products/ps6590/products_white_paper09186a00800a3ca5.shtml
Best regards,
Peter
09-02-2010 07:50 AM
Hello Peter,
we had this in the campus of some works ago and it was used for laptops
I had a vague reminescence but you have found it
Best Regards
Giuseppe
09-02-2010 04:02 PM
Fascinating...thank you, Peter.
My context (not in the original question!) makes ARP-triggered route changes impractical. The scenario involves failover between alternate WAN paths which terminate in different organizations.
After some digging, I'm wondering if a closer fit would be Cisco Performance Routing, an enhanced version of Optimized Edge Routing. A big advantage might be its capacity to reroute traffic based on link degradation as well as complete failure.
Paul
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