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New Member

CSS11503 service failover for server with 2 NICS

I have a CSS11506 currently load balancing web services for a server and 2 instances.

server1 is .61:7001

server2 is .61:8001

The B/U NIC is .64:7001 and 8001

The goal is when the .61 NIC fails the load balancer then uses the .64 NIC

The server team runs a software on the server to monitor the NICS and when the pri goes down it switches to the B/U.

I'd like a config that has both NICS and the B/U services will not be used until the Pri service goes state down.

Cisco Employee

Re: CSS11503 service failover for server with 2 NICS

Honestly, I never liked the use of dual NIC in a server when used with loadbalancer.

There is always a problem somewhere and it does not really bring any advantage.

Is the B/U NIC active when in standby ? Does it respond to arp/ping .... ?

If not, you could simply configure a seperate service for the B/U NIC and add them to the content rule. They should be down [probe] when in standby.

If the B/U NIC is always active, then it's more complicated.

The CSS allows only 1 backup service. A service that is only active if the others fail.

If this is HTTP, we can use a redirect service to go to a different content rule where you'll have as many backup services as needed.

If this is not HTTP, you'll have to use a single backup service.


New Member

Re: CSS11503 service failover for server with 2 NICS

I think this will be an adjustment on the Server and not on the CSS. The Server Admin must configure the DUAL NIC in MULTIPATH (Active-Standby Mode).

Both NIC's will be bonded to a single IP Address and single MAC-Address.

When Primary NIC is enable, it will be the one to do the ARP. CSS will detect the Primary NIC's IP/MAC address on the it's receiving interface. When Primary NIC goes down, CSS detects a link failure and removes the ARP entries on the interface. At this time, the Standby NIC will do the ARP to let CSS know of the correct interface.

On the other hand, if you want to make it harder for yourself, you need to configure

4 services for your web service


server161 - server1 pri NIC

server164 - server2 pri nic

server261 - server1 b/u nic

server264 - server2 b/u nic

With the keepalive on the each services, server161 and server261 services will be

detected (alive) while standby NIC is in down state. The Content rule only forwards the data to the services in Alive State.

NOTE: Just ensure that the B/U NIC doesn't ARP while in Standby Mode. (do a "sh arp" to verify).