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)

[Stephane_Grosj1]

ISC is totally independent.
Indeed, you need vSphere 5.1 to have LACP. If you can't, you have to stick to static LAG with all the risks that it implies...

[Alex_Joda]

Ok, I see. If we configure the ISC connection with LACP is it still possible to create static MLAG peers together with the LACP peers ? We have some vSphere Host with standard vSwitches that can only use static LAG (Route based on IP Hash) and we want to connect them to the MLAG core switches too.

[Stephane_Grosj1]

LACP should be configured for every switches connected to the MLAG Core. That way, you are less likely to create a loop, or a blackhole, because of wrong cabling, misconfiguration or config loss. If LACP is not present on the other end of the link, it doesn't come up.

As for choosing ELRP or STP, it will depend on what scenario you want to be protected from. Just be sure to never block Uplinks on access switches. In the event you create a loop by connected one edge to another edge, prefer to block the direct edge to edge link rather than the uplink on one edge.

[Alex_Joda]

Is this also true for the Cisco switches we connected to the Extreme MLAG cores with static LAG. At the moment they are all totally freezing if we have a loop on one MLAP peer and we have to unplug mains to repair this. If we use LACP for them too would that avoid it ? So ELRP would only be useful for the Extreme Edge switches we use or should be activate STP on them as with the Cisco ́s ?

[Stephane_Grosj1]

Hi,
LACP would be better in that case. With it enabled, the loop would not have been possible in your case. ELRP is great, but it's for preventing a loop on the access side.