router config issue (maybe)

cavenetllc · ‎03-27-2017

Good day to you all. I am running a cisco 3845 router with software rev. 12.4. We have an Hwic SFP card for our fiber up link and we run two gigabit Ethernet ports for our network addresses.

We are seeing speed slow downs and ping losses over the network . Sometimes it is minor and other times it is major.

I think we are having an issue with our NAT config for the Ethernet ports.

We have two sets of public addresses and we have two Nat's setup. We have both of the ports plugged into a cisco switch and they are configured as "Trunk" ports.

Any ideas on what to do to trouble shoot the config???

Philip D'Ath · ‎03-27-2017

Do you have any monitoring software? PRTG is free for up to 100 sensors. Monitoring software is great for looking at patterns when problems present themselves.

https://www.paessler.com/prtg

I would initially check for network congestion, and the speed/duplex settings of all the connected interfaces. I would also check the router log.

lpassmore · ‎03-27-2017

This sort of thing will most likely end up being a cable or interface fault, Perhaps a duplex issue although that is more rare these days

Check if there are any errors on any interfaces in the path: show interface ?

Do some normal size pings and some large packet (1400 byte) pings and see if they all get through.

Check the duplex and speed configuration at each end. They should be set to auto for Gb

Check cabling

Tools, as Philip indicated, can also be useful