24 May
2017
24 May
'17
3:50 p.m.
A "port unreachable" for UDP port 520 indeed
is not an error condition.
The gateway may not be using RIP. Or, the firewall may have been
configured
to reject port 520 traffic while ampr-ripd -r is still processing it.
(not likely because the RIP traffic is multicast so would not normally be
replied to by the firewall)
The difference would be that the IPIP ICMP unrechable will come from the
IP of the previous router's IP, while the port unreachable will return
via tunnel, from a 44net IP.