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UCS ARP Issue?

Level 1
Level 1


I have an issue I have been fighting for about a week now.  We have our chassis connected to two 6120's.  The 6120's are trunked to a Cisco 4900M switch.

I appear to have an arp issue that I can't resolve.  It could be a VLAN tagging issue also.

I have windows server 2008 installed on a blade with the virtual interface card.  I am presenting a single vnic to windows.  The server is addressed with an IP address on VLAN1.  VLAN1 is the native vlan.

If I try to ping the windows blade from another machine on the same subnet, I get a destination host unreachable.  If I ping that same machine from the windows blade I get a response.  If I then try to ping the windows blade from the same server, I get a response and see the correct entry in the arp table.

If I try to ping the windows blade from a machine on another vlan I get a successful response.  This is why I think it may be a tagging issue.

The vnic is setup in the default vlan and native vlan is checked.

Anyone have any ideas what the issue may be?



3 Replies 3

Level 4
Level 4

Sounds like ARP requests aren't making it into the Windows blade from outside. What version of UCS? Are all your 6100 uplinks configured identically on the upstream switches? They must carry the exact same trunked and native VLANs...

I would start a wireshark capture on that Windows blade. Then go to another host, clear it's arp table and then ping the Windows blade. Wireshark probably won't see anything. Then on the 4900M (the router, presumably), do a clear arp and ping the Windows blade to see if there is any difference.

Note that routed traffic works because the windows blade likely sends more traffic at the router, so its ARP table is kept up. It also has a longer ARP timeout



The correct answer has been given in the following thread:

Thanks to all who helped with my issue.


Hello. The link you posted is no longer available, can you repost the fix for this, I'm using 6100 FI's and running into what seems like the exact problem.




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