VLAN span over trunks, can only ping some devices remotely

richyvrlimited · ‎08-16-2017

I have 3 switch stacks that are geographically distant but connected via P2P links, so in essence connected via CAT5.

There are servers connected to each stack and when remotely connected to any of the 3 switch stacks I can happily ping any server connected either directly to one of the stacks or to one of the other stacks. the servers are all in the same VLAN, and have an IP address in the same network. each switch stack has it's own SVI for the VLAN

To make it easier to visualise the IP range is 10.211.15.0 / 25 and the two specific servers I'm referencing have an IP of .77 and .90

If from my remote PC (on a separate VLAN & IP range) I try to ping one of the servers 10.211.15.90 I get a response. Traceroute shows the expected hops with the penultimate hop being my core switch which has a route on it showing the VLAN being directly connected to a particular interface.

However if I try to ping the other server 10.211.15.77 I get timeouts. When I traceroute, the trace fails at the penultimate hop, i.e. the core switch.

Can anyone explain why this would be happening, as it doesn't seem to make sense!

Georg Pauwen · ‎08-16-2017

Hello,

where are you pinging from, a Windows PC, or the Cisco device (switch) ? It is possible that the server with IP address 10.211.15.77 blocks UDP packets (which are used by the Cisco device for traceroute, as opposed to Windows devices, which use ICMP for traceroutes).

richyvrlimited · ‎08-16-2017

Hi Georg.

The remote device which can't ping the server is a windows device.

I can ping the server from any of the 3 switch stacks without issue.

Cheers

Georg Pauwen · ‎08-16-2017

Hello,

check if UDP is blocked on the remote Windows device you are pinging from, the issue might be the Windows device itself...

richyvrlimited · ‎08-16-2017

I can check that, but I thought you said that Cisco devices use UDP for Traceroutes. I can traceroute & ping fine from the Switch stacks. It's from the remote PC I can't ping the server

It's certainly something to look into though, thanks.