Fixing JUNOS next-hop resolution failures
Overview I’ve recently seen a number of instances where a Juniper router will simply not forward packets correctly, often onto a “LAN” (Ethernet with lots of hosts). Looking at the routing table seems to show that everything is fine, and pinging the host from the router works, but transit traffic appears to just disappear into a black hole. This can be really annoying and hard to debug. These are my quick notes on troubleshooting and fixing this....