Cisco Bug: CSCvv26343 - Having 2x interfaces share one routing table can create asymmetrical routing issues.
Aug 19, 2020
- Cisco TelePresence Video Communication Server (VCS)
Known Affected Releases
Symptom: Currently on Expressway we only use a single routing table even when you're using a dual-interface Exp-E server, and this can cause a few potential asymmetrical routing scenarios depending on src/dst IP addresses for the connections. However, if we moved to policy based routing with per interface routing tables we could alleviate most of these issues. Conditions: Scenario 1) You are an admin who wants connectivity to both interfaces of the Exp-E from a single computer for testing and management purposes. - Currently, each source address will only be able to connect to a single interface on the Exp-E due to the static routing, but if we changed to policy based routing we can make a per interface routing table to allow the exp-e to intelligently respond to a HTTP, ICMP, SIP, etc. requests from the originating interface for the connection. Scenario 2) If you factory reset (manually or due to clustering changes) a Dual-NIC Exp-E then it will revert the Dual-NIC setting, and this can cause routing failures and martian packet errors if the default gateway was for interface LAN2/eth1 requiring console access to recover. - If we used policy based routing we would have a default gateway configured for both interfaces, and we can then make sure that main route table only includes the gateway for active interfaces.
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