Based on the fact that you are only using a single VLAN, I would first question why you are using using ISL trunking? Since ISL is used for Inter-VLAN routing, it's an unnecessary configuration, unless you are preparing for multiple VLAN's down the road. Have you configured VTP appropriately? Also, I would check for any ARP abnormalities in your CAM and ARP tables.
Kelly Cobean -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Patrick Donlon Sent: Wednesday, March 13, 2002 4:11 AM To: [EMAIL PROTECTED] Subject: Etherchannel/ISL trunk failure [7:38085] Hi everyone I have a strange problem I'd like to know if anyone can explain why it happened and how to prevent it happening again. I have two Cat 5500s connected using four 10/100 MB port configured as an etherchannel, it was also configured as an ISL trunk. It's a very simple network with these two switches, a PIX and only VLAN 1 is used. The problem occurred when clients DNS requests failed. The DNS is an NT server which was connected to Switch B, the PIX was connected to Switch A and the default gateway for VLAN 1 was on Switch A. From a PC on Switch A you could ping the NT server and the default gateway and PIX etc, but the NT server couldn't ping the default gateway. Moving a PC to Switch B replicated the problem, I could ping everything else on the network but not the default gateway. When I checked the switches I could see some errors on the first port of the channel, a few align, fcs and runts, I then noticed the port was leaving and joining the spanning tree every 30 seconds or so. Removing the cable from the port fixed the problem immediately, when the cable was put back the problem occurred after about 3 mins. I removed the ISL trunk and put the cable back and it is working and error free for over 12 hours. I'd love to know exactly what caused this, I think it was the VLAN information not being passed down the trunk but I'm not sure and as the link had to be up v.quickly I didn't have time to test a few things out. cheers Pat -- email me on : [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=38096&t=38085 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
