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Redundant supervisor engine will forward the data while is standby ?


We bought Cisco sup engine WS-SUP32-GE-3B for 6500 switches 2 nos for redundancy. I have connected 6 systems on each sup engine ports.

Anyone clarify whether both sup engine will forward the data while one is Master and other is standby ?



4 Replies 4

Reza Sharifi
Hall of Fame
Hall of Fame


In SSO mode, the primary sup will forward traffic and the stand-by is waiting until the primary goes down and then it starts forwarding traffic.  If you create on etherchannel using one port from each sup, it will use the primary sup to forward traffic.  If you pull out the the primary sup, it will fail over to the stand-by sup and the port on the stand-by will forward traffic.  I have not tested this on sup-32, but I know it works well with sup-720


Hi Raj,

When you have two SUP's for redundancy one is active and other is standby.
Incase if the active (primary) supervisor engine is down then the whole traffic will handle with the standby (secondary) supervisor engine without any outage.

Please rate the helpfull posts.

Joseph W. Doherty
Hall of Fame
Hall of Fame


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Generally the standby sup doesn't forward packets even when you can use its ports.  An exception is the VSS-720 which also uses the standby sup to increase chassis forwarding capacity.  (NB: This is not to be confused with VSS between chassis.)


Similarly, 3750 stack masters make L3 forwarding decisions for the whole stack.

Level 5
Level 5


When you are using the port on the standby supervisor on a sup32, it will work. You need to be aware that L2 or L3 forwarding is only done by the active supervisor.

In other word, if a frame arrive on the first port of the standby sup and it need to get forwarded to the second port on the same sup, the frame will first go to the active sup using de classic BUS and come back down to be transmitted.

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