VSS - Max Bandwidth Between Switches

[Robert Ho]

hey all, we're looking into the VSS system now.

plan is to inter-connect the switches via dual 10GE links.

is a single flow restricted to one link where it can only burst up to 10GE (similar to etherchannel)?

or, can the flow utilize both links between the chassis?

the reason is that we will have several nodes connected across both chassis and the aggregate bandwidth between them may burst beyond 10GE.

meaning, that nodes 1 and 2 are transferring at 6Gbps and nodes 3 and 4 at 5Gbps, where nodes 1 and 3 are connected to one chassis and nodes 2 and 4 connected to the other.

thanks

-robert

[Reza Sharifi · Accepted solution]

Robert,

In VSS, when you connect the 2 switches together using 2 10Gig interface (VSL) you are actually using an etherchannel.  So, the restrictions are the same as any other etherchannel. And as you noted the flow can only burst up to 10Gig.

HTH

Reza

[Yogesh Ramdoss]

Robert,

As Reza mentioned, if the VSL has 2x 10G links, then max bandwidth between them is 20Gig and you can have maximum of 8x 10G links in VSL.

As in any etherchannel, a given flow takes only one link, and it takes the same link as long as the link stays up.

Recommendation from Cisco is to have all devices dual-homed, means having a switch with a MEC (multi-chassis ether channel) to VSS switches.

- Yogesh