[j-nsp] MC-LAG on QFX5100

Vincent Bernat bernat at luffy.cx
Sun Jul 9 07:23:46 EDT 2017

 ❦  9 juillet 2017 09:07 GMT, "Jackson, William" <william.jackson at gibtele.com> :

> We have been testing an MC-LAG active/active setup on qfx5100 using the latest 14.1x53 code.
> We are seeing issues when using L3 in the MC-LAG.
> We are using IRB with VRRP on a number of vlans that face the downstream client.
> It seems that in active/active both nodes process traffic even if they
> are not the VRRP master, so we have taken that into account.
> The issue we are seeing seems to be that the ARP sync is not working on the ICCP between the peers.
> We can reach downstream nodes via one peer but not the other.
> And it works correctly on some vlans but not others so isn’t related to the downstream client.
> JTAC is on it albeit at snail’s pace.
> Has anyone got this working on qfx5100 and can share some config
> examples?

I ran into similar limitations with the same version. I have tried both
MAC synchronization and VRRP. When packets hit the "wrong" node (the one
that didn't learn the neighbor information), they are not
forwarded. See:


I got additional private feedback from people with similar issues
(MC-LAG and L3 forwarding). I didn't try to involve JTAC.
Don't stop at one bug.
            - The Elements of Programming Style (Kernighan & Plauger)

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