I am using Cat 3500XL switches in a LAN connected to multiple Sun Workstations (with quad ethernet NICs installed). We are seeing Link Down/Up error messages which are causing problems since we are using NFS. I understand that out of tolerance jitter on the NIC can cause this problem. Other than replacing the card (which is expensive since it has the name SUN on it), Cisco recommends opening up the jitter tolerance with the command "carrier-delay 4". This increases jitter tolerance. Not sure what the default for this parameter is, but would like to know what the downside of opening up this parameter is. Obviously there is a downside or it would be opened up at all times. Any info is appreciated.