EMC Data Domain LACP

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Hello,
We have an EMC Data Domain that I'm connecting to two X670G2 switches (XOS 15.6.3.1p9) - with one network port per 670
The two 670s have a 10G ISC MLAG between them, the Data Domain's ports are part of the MLAG
The Data Domain's LACP has been configured to "XOR Hash L2 and L3"

My questions are:
- Does my version of XOS support XOR Hash L2 and L3?
- If not: does a newer version support it? Or what do I best set my switches to?
- Or do I have to reconfigure the Data Domain to something like L3_L4 (without the XOR, I think)
- Do I even have to bother with it, given that the Data Domain only has one port per switch, i.e. shouldn't the MLAG take care of everything - or do I have to do an "enable sharing 17 grouping 17 algorithm ...", which I've done in the past, thinking it won't hurt?

I know... I should know this, but I'm starting to confuse and doubt myself at this point.

     Frank
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Frank

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Posted 2 years ago

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ChrisH, ESE - Employee

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Hi Frank,

Without knowing the exact configuration and design any details are a bit tricky to tell, however in general you shouldn't be worried.

With MLAG, traffic that is being sent to the host (in your case the EMC) from the network is always being sent out the local MLAG port and never over the ISC to the peer for forwarding to the host.
  
Let's take the topology in this link for example: https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-configure-MLAG-in-Extreme-switches
Traffic going to the server that enters the switch on the left will always go via the direct link to the server and traffic that enters this MLAG setup via the right switch, will always take the directly connected link on the right.  There is no algorithm needed, as this traffic is never being load-balanced or shared between the two links.  The forwarding happens always locally, so this is something that needs to be considered in the design (i.e. when blocking certain links with STP, EAPS or similar).

The only part where the sharing algorithm does play a role is on the host itself (in your case the EMC) with traffic leaving the EMC and being sent out into the network.
Here the algorithm simply decides which of the two links the traffic should be placed onto, but for the EMC it doesn't matter if the other side is now one, or in case with MLAG, two different switches.

Please be aware that this is a bit different when using a two-tiered MLAG setup, as in this case the MLAG peers will also act as host and therefore have a shared link to additional MLAG switches.
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Frank

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Chris, thank you so very much - especially pointing to the How-To that I apparently didn't find...
In short, it works the way that I thought it would work before I started to overthink things!
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ChrisH, ESE - Employee

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No worries, Frank, I'm glad if I could be of help..