I'm running SLES 12 SP3 in a production environment. There are several interfaces configured on two separate networks. Things are working fine for a while(days at a time) and for no apparent reason, 1 or 2 of the gateways will get dropped from the route table. There is no indication as to why in any logs(/var/log/messages). The ARP table still shows entries from the interfaces in question to the router IP addresses.
I know the Linux kernel does route table garbage collection, and there are tunables related to this. But the route table doesn't appear nearly full, there are less then 50 entries in it. Are there other events that cause the Linux kernel to remove a gateway from the route table? Are there other places I should be looking on the system for clues as to why the router was removed?
Thanks in advance.