[j-nsp] Weird ARP issue

[Luca Salvatore]

I have a very strange problem that may or may not be related to my switch, but I'm running out of ideas.


I have a EX4200 switch running 11.4R2.14.  The EX has a bunch of VLANs and is doing some basic routing using the L3 VLAN interfaces.
Connected to this switch is some servers running XenServer with a bunch of VMs.

Now, the issue I'm seeing is:
When I try to SSH to a VM running on the XenServers i don't get any connection.
If I then send a ping to the VM my SSH connection works.

What I see happening is that there is no ARP entry in the switch when I use SSH.
As soon as I send a ping, the switch sends an ARP request and gets a reply.

In other words:
When SSH is used and I do a TCP dump on the server I do not see an ARP request
But when I send a ping, I see the ARP request (from the switch) hit the server and the response comes back, the switch the has an ARP entry and everything works.

Wondering if anyone has any thoughts here?
I'm about to do a port-mirror to try and dig a bit deeper, but not really confident it will help.

Thanks
Luca.