I am currently having an issue using DHCP relay between different routing-instances. The DHCP-client sends DHCP DISCOVER message to routing-instance zone-CLIENT-vrf interface ae0.100, where dhcp-relay is configured and relays the packet to DHCP-server with IP address 192.168.2.8 in routing-instance zone-SERVER-VRF. The DHCP-server then sends DHCP OFFER message to routing-instance zone-SERVER-vrf interface ae0.200, where dhcp-relay is configured to forward-only-replies, but drops the packet with the error message "BOOTPREPLY could not find client table entry"
After working with the JTAC for almost a month we were finally able to get the issue resolved. It all came down to the fact that Windows Server 2008 does not support Option 82. As soon as we deployed a new DHCP server running Windows Server 2016 the issue was immediately resolved. I'm glad we finally got past this one!
We had the same problem when trying to migrate from legacy helpers bootp to jdhcp(dhcp-repay). Our main goal was to achive just DHCP relay, without creating bindings or subscribers on Juniper MX480. We configured dhcp-relay in a vrf(l3vpn) like this:
After configuring dhcp-relay, we noticed that DHCP Discover packets are relayed to DHCP Server then, server replays with DHCP Offer but, unfortunately DHCP Offer was dropped by MX. When tracing, the following log was seen:
jdhcpd_packet_handle: BOOTPREPLY could not find client table entry
After hours and hours(actually days and days) of troubleshooting, we found that according to RFC, if DHCP Discover packets contains DHCP Options 82 information, then, server, should replay with DHCP Offer containing the same DHCP Options 82 information as it was in the initial packet. Here is the statement from RFC:
DHCP servers claiming to support the Relay Agent Information option SHALL echo the entire contents of the Relay Agent Information option in all replies.
After changing on DHCP Server side, to return Options 82 information in DHCP Offer messages, everything works perfectly.