Scenario: Class B subnet 172.16.0.0/16 with about 500 hosts. Cisco3640 core router as dgw of the network, address 172.16.1.116 Cisco 1712 vpn gateway, address 172.16.1.108 Cisco Pix506 vpn gateway, address 172.16.1.107 Other networking gears not related (hope) to this issue Eigrp protocol running on all the devices except the pix.
Recently the customer is experiencing problems reaching the subnets at the other end of the tunnels terminated by the pix, here are some tests I've done and some details I've collected:
If I ping the address of the internal if of the pix (172.16.1.107) from the3640 (remember, this is the dgw of the subnet), all seems ok. If I do a trace from 3640 to the same address I surprisingly see the packets going to the 1712 (172.16.1.108) and back to the 3640 (due to the eigrp table), so forth until the ttl expires. Routing tables are all ok Arp tables are all ok No cef or netflow running No policy routing No proxy arp enabled on any device. Cpu usage of all the devices is as usual 1712 is injecting routes to the internal lan in a fairly controlled fashion due to distribute lists. Same devices are running quite from a while, no important changes made to the images or configs lately.
Strange enough, if I change the ip of the pix with an address near to the old one the problem stands, if I change the address, and only that, with one quite far from the old one (now is 172.16.1.5) the problem suddenly disappears, however none of these addresses belong to any other host or device (tried to ping after the change). Anyone has experienced something similar in the past? Bye, Tosh.