Intermittent connectivity on LAN

mfawehin · ‎09-17-2008

Can anyone help with this please, we are experiencing intermittent connectivity between devices connected to the same switch and within the same vlan. This is now every hour and the outage lasts about 3 to 5 minutes. The server guys report RDP and DNS connectivity errors - The connectivity verifier "x.x.x.x RPC" reported an error when trying to connect to x.x.x.x.

Reason: The request has timed out.' and the servers lose connectivity to each other. I have checked several times ans all ports are fine with no errors, the vlan is functioning fine, all servers have speed/duplex forced and use the same def gtwy etc.

The switch has even been replaced but yet these problems persist.

The server guys have changed nic, drivers etc on all three servers affected.

Any ideas, getting desperate???

satish_zanjurne · ‎09-17-2008

1.Hope you have checked for any logs on the switch ?

2.If servers can be taken off & then connect desktops or laptops on those ports exactly , where sservers were connected ??

3.You must have tried connecting servers on different ports also ??

mfawehin · ‎09-17-2008

Thanks for the response, we have attached exchange, domain server and an isa server to these ports and have moved them to other ports as well. While there is connectivity to the server from other networks, these servers on the same lan are unable to connect to each other.

milan.kulik · ‎09-17-2008

Hi,

broadcast/multicats storm possibly?

Have you tried data capturing at the moment the connection fails? It should be possible if that happens every hour...

BR,

Milan

mfawehin · ‎09-17-2008

I am remote to the site and have no tools to use, have you any freeware suggestions. The server guys are going to use netcap to capture some infor later.

Is there any commands on the switch that can show an indication of broadcast/multicast storms?

Davidamoore · ‎09-17-2008

Goto http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.1E/native/configuration/guide/storm.pdf

This is from the cisco site and should get you started on storms

mfawehin · ‎09-18-2008

Thanks to everyone who responded, it transpired that the problem was caused by proxyarp not being disabled on the ASA connected to the LAN switch.

Once proxyarp was disabled on the interface, the servers started communicating.