Router drops one packet?????

[sketterman]

Can anyone explain this? We had a server in Site B all of the sudden drop off of the WAN from Site A connected via leased line. Every other server and workstation can be reached via Ping or via Name resolution over the wan, so i would not suspect a router problem. When I connect to the router in site B (the site with the server) i can ping it!!! So, the packet is being dropped at this router on the trip back to Site A. But no other packets are being lost except this ONE server. No subnetting, no access lists, very basic setup. Route table is correct. Arp is correct. No proxy arping. I don't get it. Now, when I ping this server from the router that it answers to, i do see Frame and CRC errors. All hosts also see this server except for anyone over the WAN. Could a router drop a packet due to CRC errors/frame errors while a switch would not????

[donewald]

Good question.. The Answer to this is Yes. Switches can implement several forwarding methods (Fastforward, Store and forward, Cut through, etc). All but Store and Forward can and will send packets based on only a subset of the complete packet (for speed). So since Cut Through for example only looks at the Destination Mac this switching method would not recalculate CRC and thus forward packets that could be corrupt. The router always runs CRC / Checksum so this would not occur.

Hope this helps you,

Don

[rjackson]

Sounds like a gateway issue. Can the router ping the server using extended ping and an address not on the servers network? Check the servers gateway and mask.