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MLAG, Does the ISC vlan forward any payload traffic


Userlevel 3
MLAG ISC

I have a question

For a customer I have these options

Between the 2 MLag switches are these options

  1. A 2 port aggregation of 1 gig links
  2. A single 10 gig link ( a newer network )
So the trade off I have is bandwidth vs resilience.

So this is my question

Does the ISC vlan forward any payload traffic ? or this is purely a control channel is which case it would seem prudent to use the lower bandwidth but resilient link.

2 replies

Userlevel 7
Hi,

there'll be traffic on the ISC in the following cases (that comes to my mind):

- BUM traffic (broadcast, unknown unicast and multicast) will transit through ISC, to be dropped on the other end in steady state operation.

- single attached devices, statistically ~50% of the traffic to them will transit through the ISC

- link failure (similar to the previous case)

- L3 traffic (VRRP) if you don't have Fabric Routing on

- in some advanced designs with an IGP (OSPF) on top of MLAG, you can see steady traffic on the ISC as well

Best Regards,
Stephane
Userlevel 3
Grosjean, Stephane wrote:

Hi,

there'll be traffic on the ISC in the following cases (that comes to my mind):

- BUM traffic (broadcast, unknown unicast and multicast) will transit through ISC, to be dropped on the other end in steady state operation.

- single attached devices, statistically ~50% of the traffic to them will transit through the ISC

- link failure (similar to the previous case)

- L3 traffic (VRRP) if you don't have Fabric Routing on

- in some advanced designs with an IGP (OSPF) on top of MLAG, you can see steady traffic on the ISC as well

Best Regards,
Stephane

Thankyou Stephane

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