Two tier MLAG

[EtherNation_Use]

Create Date: Sep 22 2012 7:42AM

Can I possibly request urgent help with a two tier MLAG solution that I am trying to PoC. I basically have four X460s connected together in a full mesh. Two switches will emulate a Core and two to emulate edge switches.

1. Core1 connected to Core2 across an ISC consisting of two ports aggregated in a regular LAG.
2. Edge1 connected to Edge2 across an ISC consisting of two ports aggregated in a regular LAG
3. Core1 connected to Edge1 (2ports LAG) and Edge2(2ports LAG)
4. Core2 connected to Edge1 (2ports LAG) and Edge2(2ports LAG)

My question is how and where would I setup the LAG and MLAG between the Core and Edge. Here is my present config

1. On the Edge1 and 2 switches, the ports going to both Core switches are setup as a regular LAG.
2. On the Core1 and 2 switches, the ports going to the Edge1 switch are setup as a MLAG with id 1 and the ports going to Edge2 are setup with MLAG with id 2.
3. I was under the impression that the connection from each of the Core to both Edge switches could be setup as a MLAG on the Edge switches as well so that you would have MLAG at both ends.

There is presently a loop and the CPU percentage is around 40-50% which is not great. I cannot go to production with this.

I am following the concepts guide but it is sort of thin on details when it comes to the two tier config. I have two VLANS to emulate edge VLANS and they are propagated all across (on all uplinks - tagged). Any suggestions pls. (from Anush_Santhanam)

[EtherNation_Use]

Create Date: Sep 27 2012 11:51AM

Hey ExcaliburYes you are correct you do not need either ELSM or ELRP in MLAG. ELSM is great for protecting against a neighbor switches CPU getting over run and making a link go down and is great for EAPS/ERPS. But in this case doing that will not help with MLAG.Hope that helps.P (from Paul_Russo)

[Alex_Joda]

Played a little with ELRP today and it looks really nice. So why should one use it only on the access side ? If we run it on the MLAG core pair and exclude the ISC it should also prevent any loops....

ELRP is so easy to setup that I asked myself why I should worry about LACP and STP (at least on the Extreme switches). Is there any disadvantage using it ?

[Stephane_Grosj1]

never say never 🙂
I have seen servers with 2 NIC starting to bridge between them, even though not configured for it.

But I agree. Configure LACP on NNI side and use STP or ELRP on the UNI side. That should be good enough to prevent 99% of loop potential.

[Alex_Joda]

In this case we only have an Enterprise license without the Plus...That means no distributed switch. But a host cannot create a loop anyway, so it should be O.K. to go with LACP for the switches only.....