Solved: ports requirement for new VSS core

mateens · ‎02-13-2018

Hi,

Both switches in VSS should have identical config. That means that they also should have same number/type of ports ? e.g one VSS member connecting with 10G and other 1G to same access/dist. switch wont work ?

Giuseppe Larosa · ‎02-13-2018

Hello Mateen,

the whole idea under VSS is that the two devices pretend to be a single box to the outside world.

So yes they need to have the same list of modules and linecards because they use a multi chassis etherchannel to an access switch and this requires to use links of same speed

>> That means that they also should have same number/type of ports ? e.g one VSS member connecting with 10G and other 1G to same access/dist. switch wont work ?

Yes it wouldn't be impactless for the network you would need to rely on STP convergence when the 10G link fails and in that case the 1G link will become the new uplink. You cannot put in the same bundle interfaces of different speeds.

As explained above the way VSS work you need to use links of the same speed towards an access device in order to create a multi chassis etherchannel.

Hope to help

Giuseppe

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Giuseppe Larosa · ‎02-13-2018

Hello Mateen,

the whole idea under VSS is that the two devices pretend to be a single box to the outside world.

So yes they need to have the same list of modules and linecards because they use a multi chassis etherchannel to an access switch and this requires to use links of same speed

>> That means that they also should have same number/type of ports ? e.g one VSS member connecting with 10G and other 1G to same access/dist. switch wont work ?

Yes it wouldn't be impactless for the network you would need to rely on STP convergence when the 10G link fails and in that case the 1G link will become the new uplink. You cannot put in the same bundle interfaces of different speeds.

As explained above the way VSS work you need to use links of the same speed towards an access device in order to create a multi chassis etherchannel.

Hope to help

Giuseppe

Joseph W. Doherty · ‎02-13-2018

To expand a bit on what Giuseppe has already noted, pay attention to he assumes you'll be using Etherchannel between the VSS cluster and the downstream device. For such, as he notes, you'll want to use identical line cards.

However, if you were doing L3 on p2p links, or L2 that's not Etherchannel, the VSS upstream ports don't need to be alike. This, though, is negating the purpose of using VSS.

Further, and I'm unsure about this, it might be possible to mix some not exactly the same line cards. For example, it might be possible to use a 6724 and a 6748 port on different VSS members, as both cards have similar architectures. Further, you might be able to mix dissimilar architecture line cards (as you can on a single chassis), with additional configuration. What you cannot do, as far I know, is mix different bandwidths in the same Etherchannel.

mateens · ‎10-26-2018

Hi,

Ended up getting cisco 9407 pair with sup XL. Can you pls give this question a look ?

https://community.cisco.com/t5/switching/installing-upgrading-from-1-core-switch-to-2-without-downtime/td-p/3733577