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3750 stackwise and port-channel

john.dejesus
Level 1
Level 1

scenario:

3750a, 3750b, and 3750c are connected via stackwise. these switches are then connected to g0/1-3 of 3560G via port-channel.

3750a-g1/0/1-----g0/1-3560G

3750b-g2/0/1-----g0/2-3560G

3750c-g3/0/1-----g0/3-3560G

question:

1. what would be the outcome if one of the 3750 has been disconnected in the stack membership? for e.g. 3750b's stack-cable is remove.

2. if the root of all vlans is 3560G. what would be the result of stp topology in 3560G's perspective? since 3750b has been remove from the stack. I assume that the port-channel membership in 3750's perspective would be (g1/0/1 and g3/0/1)

1 Accepted Solution

Accepted Solutions

but what about in 3560G's perspective, does g0/2 still be a part of the port-channel?

no, as soon as the physical link on the 3750 side go down, the same happens on 3560 side.  So you loose that one link on both 3750 and 3560.

HTH

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5 Replies 5

Reza Sharifi
Hall of Fame
Hall of Fame

If the 3750s are stacked, they are logically one switch.  So, if you loose one, nothing should happen since you have uplinks form other switches in the stack.  And the Portchannel will have 2 links in it instead of 3.

HTH

FYI. i forgot to include this scenario.

***the connection of 3750b-g2/0/1-----g0/2-3560G is still active. only the stack cable of 3750b is remove.

since only the stack cable was removed. Yes Reza, 3750 will only have 2 active members in the port channel link. but what about in 3560G's perspective, does g0/2 still be a part of the port-channel?

If no, then I assume that 3750b-g2/0/1 is the DP and g0/2-3560G is the RP?

If yes, is this some sort of violation in port-channel? what will be the effect on the users connected (if any) to 3750b?

but what about in 3560G's perspective, does g0/2 still be a part of the port-channel?

no, as soon as the physical link on the 3750 side go down, the same happens on 3560 side.  So you loose that one link on both 3750 and 3560.

HTH

great thanks.

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