Network Collisions

RouterOS General
1

I have a Cisco 7200 DS3 router at my POP and it has one ether interface with a CAT5 that goes into a switch. In that Cisco 2950 Catalyst switch I have 3 servers, an APC Mater Power Switch, and 3 Mikrotik Routerboards.

I recently had a slowdowns and 3-10% packet loss showing up between the routerboards and the Cisco Router. I checked the CAT5 cables(each 220-250’) and connectors, replaced the routerboards(which are backhauls shooting to other towers), PoE, and patch cables in the switch. No difference. I also have Packet Loss when pinging from one routerboard to the other thru the switch, and the bandwith tests are showing 20Megs between the 2 routerboards.

Obvious fix -

swap out the Cisco 2950 switch

I did that and put in a linksys switch that has a LED for Packet Collisions. Eyes were opened to some collisions. That light will not flash if only the servers are plugged into the switch, but as soon as either routerboard is plugged in, the LED starts flashing- pretty fast too.

I have looked for anything obviously wrong in the routerboards, and I have been looking for a possible log or something in the Cisco IOS to find why we are getting the collisions. I know about CDMA but I am not as seasoned on Mikrotik or Cisco as I want to be, but maybe someone is, and can throw me any possible ideas.

Thanks a million!

2

Hook up the Catalyst switch again and post the output of “show interface” for the interfaces involved in your setup.

3

its probably running at half duplex? Full duplex 100/1000 cannot have collisions. Remove auto-negotiate on both sides and fix them both to 100 Full and try again.

4

Sorry Guys! It was running Half Duplex. I never set it that way, but I found it, made it Full and we were golden! :smiley:

Sorry for leaving you hangin’.

5

wow, more than half a year of silence - and viola, the solution ))