Cisco Catalyst 6500 VSS Configuration

Answered Question
Dec 3rd, 2009

Suppose I have two Catalyst 6509 switches in VSS

configutatoin. I have one point-to-point circuit that comes into po

rt1/1/2 of the active chassis. What happens if the supervisor engine of the active chassis fails?

Will the stand-by chassis take over and somehow use the port of the failed chassis?

Thanks,

MAQ

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Correct Answer by Reza Sharifi about 7 years 2 days ago

Mohamad,

No, when the primary or secondary switch fails, none of the ports for that particular switch are useable, that is why for example if you are connecting your servers to a VSS set, you should always use 2 NICs from each server, one connects to one 6500 and the other connects to the other 6500.  This way you have switch redundancy (VSS) and also NIC redundancy.

Also, if you are connecting your edge devices, you should uplink you edge device two different 6500 using EtherChannel.

HTH

Reza

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Reza Sharifi Thu, 12/03/2009 - 08:32

Hello MAQ,

When you configure 2 Cisco 6500 switches as VSS, they are physically to devices, but logically one device.  So when the primary box fails the secondary box will take over the responsibility without any down time.  Also in VSS pair you only have access to the primary and not the secondary

Another word, the configs of both switches are merged and you configure every thing from the primary device until the primary fails.  The concept is similar to stacking 3750 switches together, but VSS is for bigger switches.(6500s only)

Please refer to this document for more info:

http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/DC_3_0/DC-3_0_IPInfra.html#wp1044715

HTH

Reza

Mohamad Qayoom Thu, 12/03/2009 - 08:38

Thank you, Reza.

So if the primary switch fails. will we be somehow able to use the blades or ports that are on the primary switch.

For example:

SW1 --> primary/active

SW2 --> stand by

SW1 --> fails

SW2--> primary/active

Will be able to use a port of SW1?

Thanks,

Mohamad

Correct Answer
Reza Sharifi Thu, 12/03/2009 - 08:53

Mohamad,

No, when the primary or secondary switch fails, none of the ports for that particular switch are useable, that is why for example if you are connecting your servers to a VSS set, you should always use 2 NICs from each server, one connects to one 6500 and the other connects to the other 6500.  This way you have switch redundancy (VSS) and also NIC redundancy.

Also, if you are connecting your edge devices, you should uplink you edge device two different 6500 using EtherChannel.

HTH

Reza

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