VSS Testing

Answered Question
May 28th, 2012

Dears,

I have setup a VSS between 2 6509-V-E switches. Config is working fine. But now i want to test if VSS is works in case of disaster. I have two links for VSL, one between line card of X6716-10G  on each switch and one through the SUP-720-10G TE interface respectively bundled together. If my understanding is correct, one sup (master sup) takes up the control of all line cards in the vss domain and other sup goes on standby. incase of failure of first sup, the second sup should take charge of the line cards. To simulate this i removed one of the sup which was active in vss domain. but i was amazed to see that all the line cards on that chassis got powered off. the second 6500 sup took over only on the line cards which were in its own chassis. There was one vsl link still connected between the line card X6716-10G between both 6500. Does this happens?  Please tell me what method i can use to test VSS?         

I have this problem too.
0 votes
Correct Answer by Leo Laohoo about 1 year 10 months ago
To simulate this i removed one of the sup which was active in vss domain. but i was amazed to see that all the line cards on that chassis got powered off.

Of course the remaining line cards of the primary VSS switch (switch 1) powers down.  This is because the power controller is found in the supervisor card.  As what the previous post has discussed, this is normal.  You want "real" redundancy in case of a supervisor card failure then you need to think about dual VSS supervisor.

Take note that in a scenario of a dual supervisor, say Switch 1, if one of the two fails the two chassis reboots (I believe as I haven't tried using dual supervisor yet).  If this is the case, don't be alarmed because work is on the way to address this issue.  The main objective was to enable dual supervisor to work.  With that completed a new IOS will be released that will allow non-disruptive takeover in case one VSS line card fails.

Correct Answer by ajnallicruz about 1 year 10 months ago

That is normal. The Data plane on both switches is forwarding. The Control plane is only active on one switch. If either switch loses its sup it will go down there's no way around that, but ideally all connections to a VSS pair will be redundant so you can survive the loss of any one switch.

The whole point of VSS is that you can build always forwarding topologies with multichassis ether channel, plus you get the benefit of a single management plane.

So to test it you would simply shut down one of your links in the bundle or as you've done kill the whole switch. In either case you should continue forwarding packets perhaps with a small interruption in the latter scenario depending on your setup and which switch is killed.

Sent from Cisco Technical Support iPad App

  • 1
  • 2
  • 3
  • 4
  • 5
Average Rating: 5 (2 ratings)
Correct Answer
ajnallicruz Mon, 05/28/2012 - 08:47

That is normal. The Data plane on both switches is forwarding. The Control plane is only active on one switch. If either switch loses its sup it will go down there's no way around that, but ideally all connections to a VSS pair will be redundant so you can survive the loss of any one switch.

The whole point of VSS is that you can build always forwarding topologies with multichassis ether channel, plus you get the benefit of a single management plane.

So to test it you would simply shut down one of your links in the bundle or as you've done kill the whole switch. In either case you should continue forwarding packets perhaps with a small interruption in the latter scenario depending on your setup and which switch is killed.

Sent from Cisco Technical Support iPad App

Correct Answer
Leo Laohoo Mon, 05/28/2012 - 15:24
To simulate this i removed one of the sup which was active in vss domain. but i was amazed to see that all the line cards on that chassis got powered off.

Of course the remaining line cards of the primary VSS switch (switch 1) powers down.  This is because the power controller is found in the supervisor card.  As what the previous post has discussed, this is normal.  You want "real" redundancy in case of a supervisor card failure then you need to think about dual VSS supervisor.

Take note that in a scenario of a dual supervisor, say Switch 1, if one of the two fails the two chassis reboots (I believe as I haven't tried using dual supervisor yet).  If this is the case, don't be alarmed because work is on the way to address this issue.  The main objective was to enable dual supervisor to work.  With that completed a new IOS will be released that will allow non-disruptive takeover in case one VSS line card fails.

khurram-noor Tue, 05/29/2012 - 05:35

Hi, Well I am a bit confused, but i have no other option than to accept it. Thanks for your replies.

Leo Laohoo Tue, 05/29/2012 - 15:28
Hi, Well I am a bit confused, but i have no other option than to accept it.

Thanks for the ratings.

You don't need to "accept it", per se.  Just keep an eye out.  Like I said, dual supervisor per VSS chassis is now supported but it's not yet fully "operational".  I believe by mid-next year the fully-redundant and "hit-less" IOS for a single supervisor failure in a dual supervisor chassis will be released.  This is what you may want to investigate. 

Actions

Login or Register to take actions

This Discussion

Posted May 28, 2012 at 4:56 AM
Stats:
Replies:4 Avg. Rating:5
Views:834 Votes:0
Shares:0
Tags: vss, testing
+

Related Content

Discussions Leaderboard

Rank Username Points
1 14,997
2 8,150
3 7,720
4 7,078
5 6,710
Rank Username Points
185
80
59
57
55