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Trunk Failover with Virtual Connect Flex-10

chuckk281
Trusted Contributor

Trunk Failover with Virtual Connect Flex-10

A failover question from Robert's customer:

 

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VC experts,

 

I’m pretty sure we used to do this with an add on application.

Can anyone advise how to do this in this environment ?

 

From customer:

 

We have multiple devices feeding the Flex-10 switches with different networks.   We then aggregate (trunk) these networks into a single interface (say LOM-1a) using the multiple network option and pass the traffic as tagged into an ESX host.     What we discovered is that even if the Ethernet networks (VC terminology) are defined with smart link, the interface to the server remains connected and active as long as a single assigned VLAN is online (for example only one of the switches feeding the VC fails).    This presents a challenge with VMware, as it doesn’t detect a NIC failure unless all VLANS are down and will isolate the VMs with no network during a partial failure.    Is there a way to set the interface to the server to go offline if any of the associated networks go gown (as opposed to all)?

 

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From Robert:

 

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This is a know condition, and expected behavior.  Any time you take networks from different uplink sets or dedicated ethernet connections, and configure them as multiple networks on a single ethernet connection on a server profile, this can occur.  VC prevents unhealthy networks from taking down the connection if there are any healthy networks surviving on that multiple network connection.  This was a conscious decision to not disable the ethernet connection if there were any healthy networks still part of the connection.

 

Smart link emulates Cisco link state tracking or Procurve upstream failure detection.  The intent is to monitor one upstream path for failure, and disable ports associated with that path.  In this scenario there are multiple disassociated uplink paths being monitored, with disassociated networks.  A single failure would not trigger Smart Link.  For Smart Link to disable the ethernet connection, all paths associated with all networks in the multiple network set would have to fail.

 

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Other comments or suggestions?

1 REPLY
marcelkoedijk
Frequent Advisor

Re: Trunk Failover with Virtual Connect Flex-10

Smartlink is disconnected the server downlink ports only when all uplinkports on a the same shared uplink set failed.

 

Smartlink detect only hard link failures, broken uplink ports, swith outage etc. When the edge switch is isolated, no gateway or ip traffic (layer3 issue), but the uplink ports are still up, smartlink will not triggered.

 

The default settings in a vswith in vmware does a link failover when the downlink port is disconnected.

 

I dont know if "beacon probing" is a solution for this, never seen it in the cookbooks ass option, beacon probing should generate more broadcast traffic, maybe its a thing to look at, but not for sure.