We have a stack of 670-g2's running 126.96.36.199 patch1-1 The problem presents itself on a particular vlan. Users report not being able to connect (they connect using DHCP). The issue is reproducable. I connect a computer to a copper SFP in the 670-g2 stack that has been setup on the same subnet, DHCP does indeed NOT work. I static my computer on the subnet, and am able to connect, it DOES work. The only fix i have found was to completely remove the subnet and re-add it from scratch to the 670-g2 stack. Then it immediately starts working again. It seems to happen roughly every couple of weeks, though I can't develop an exact pattern. Other subnets on the stack work just fine.
(We have had this issue prior with different hardware 670s (non g2) running older... 15 code. In this case it was a different vlan in question but all the same symptoms)
Users --> 670g2 stack --> Wan firewall --> Windows DHCP server
To provide additional information, I have access to the wan firewall logs. Typical / working communications I see the WAN firewall seeing a source of the subnet's ip interface talking to the Windows DHCP server on service dhcp-relay many entries of this.
When the subnet is "broken" instead I see the Windows DHCP server talking to the subnet's ip interface on service bootp (just one entry and nothing else). So the source is the DHCP server not the interface as normal.
The windows server admin has looked at the DHCP server and can't find anything there (we're not running out of leases, the server can communicate to the 670-g2 stack, etc).
The subnet looks like from ospf perspective, the network knows about it.
Instead of doing the band-aid fix (remove and re-add the subnet) I'd like to try and get to the bottom of what this could be...
I have opened a case with TAC but figured it would be great to get additional tips / tricks / ideas here on the community.
Thanks in advance,