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Beginner

6500 VSS connectivity

Hi,

I am looking to optimize my 6500 VSS based architecture as per customer requirement due to cost contraints....

Kindly find the ppt document attached for your perusal.

Question/Query:

I am connecting edge switch to single chassis in VSS bundle. In case the sup engine in VSS chassis fails, will the data forwarding happen…

One vsl link is through sup engine 10 Gbps card and second is through 8 port 10 Gbps Line card.

Also find VSS whitepaper link given below

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps9336/white_paper_c11_429338.pdf

WIth Best Regards

Puneet

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: 6500 VSS connectivity

again, it is not specific to VSS. If you had standalone non-redundant system you would see same impact with sup-redundancy. If network cannot be deployed with redundant and diversified network paths then to minimize network outage it is recommended to deploy dual-sup per chassis that provides stateful sup redundancy.

From the control-plane and network topology perspective VSS does not bring many advantage to single-home devices anyways...

thanks,

rahul.

9 REPLIES 9
VIP Expert

Re: 6500 VSS connectivity

You will loose connectivity, because when sup fails the whole chassis fails and what ever in connected to it. The correct way to do it is to connect the edge switch to both VSS devices using a Portchannel.  This way, if the first sup fails, you still have connectivity using the second switch/sup

HTH

Beginner

Re: 6500 VSS connectivity

Cisco has provided MEC to avoid this scenario in VSS.

Beginner

Re: 6500 VSS connectivity

thanks Reza for the help provided...

Somehow I am waiting for an confirmation from cisco Partner help online..

Will revert back with my inputs.

Rgds

Puneet

Cisco Employee

Re: 6500 VSS connectivity

Hello Puneet,

Such network designs are single-homed connections, this lacks of taking advantage of load-sharing network resources and certainly faces reliability challenges. This design principles are independent of VSS or in Standalone. Unlike Standalone, VSS now runs critical VSL interface that carries system control-plane traffic and it is always recommeded to minimize the data-load passing thru over the VSL.

Considering you have VSS with distributed physical paths, MEC gives you opportunity to simplify network topology and operation with single logical and p2p (L2 or L3) connections. And with its unique distributed traffic-engg capability, it will minimize VSLfor optimal load-sharing and redundancy from the fwding perspective.

If cost or lack of EtherChannel support is factor to build redundant path from each device to VSS pair, then the recommendation is to deploy  intermediate L2 switch between VSS and single-home devices in redundant mode. This switch should dual-home to VSS to deliver better reliability for path/node redundancy...

thanks,

rahul.

Beginner

Re: 6500 VSS connectivity

Hi,

I would like to thank you for the replies recieved...however would like to share the fact that as per cisco PH...the toplogy as shown in attachment is supported....

With Best Regards

Puneet

Cisco Employee

Re: 6500 VSS connectivity

Single-home connection is supported configuration, but not the recommended network design...

thanks,

rahul.

Beginner

Re: 6500 VSS connectivity

I think, question in VSS environment is:  will it disrupt my traffic and end users (

in case of an access switch).

As Rahul has mentioned that this is not a recommended design and not only this, when active sup will fail then all modules in that chassis will fail until it is back up. I would install VSS because it provides MEC capability else, I would be fine with two switches and doing load sharing by adjusting spantree variables.

Cisco Employee

Re: 6500 VSS connectivity

again, it is not specific to VSS. If you had standalone non-redundant system you would see same impact with sup-redundancy. If network cannot be deployed with redundant and diversified network paths then to minimize network outage it is recommended to deploy dual-sup per chassis that provides stateful sup redundancy.

From the control-plane and network topology perspective VSS does not bring many advantage to single-home devices anyways...

thanks,

rahul.

Highlighted
Beginner

Re: 6500 VSS connectivity

In order to summarize, I was looking to answer customer's question of whether this scenario will work or not..

Moreover mosts of the posts available in blogs as well as cisco were giving the impression that this will not work...

You can take this as a technical question at best in order to satisfy end customer's query.

However I do understand that in order to leverage the advantages of VSS, the connectivity has to be dual homed.....

Anyways thanks again for participitaing in the discussion.

Regards

Puneet

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