So recently we received notification from one of our remote branches that certain PCs were unable to connect to the internet. We determined that DHCP was the cause. The basic L3 path between the remote branch and the dhcp server is
DHCP Server (VM) - R1 - R2 - ASA - VPN Tunnel - ASA - R3 - Remote Client
We recently had a UPS failure that caused R1 and R2 to reboot. Not sure if that could be relevant.
Anyway, I can ping clients on the remote subnet from our DHCP server fine. I can also tracert to the default gateway for that remote subnet.
R3 is set as a DHCP relay to DHCP Server.
When our client sends out a DHCP DISCOVER it's able to reach our DHCP server. Our DHCP Server then sounds out a DHCP OFFER which is met instantly with:
That screenshot is taken from a packet capture on the DHCP Server. Isn't that time between messages incredibly short for a TTL expiration? Also, this seems to be the only kind of traffic that's unable to pass through.
The ICMP comes from our gateway interface to the ASA.
I'm baffled by this.
Let me know what else I can provide to help.