Hello all,
I am upgrading a older 2950(100M) switch replacing it with a gigabit 2960. Installed it in the same rack, the configuration is practically non-existent just set the passwords and IP. We run a single VLAN flat network for this so I started out by patching it to the existing switch, after a few days we had an opportunity to migrate because there was some downtime so I disconnected the cables on the old and moved them to the new.. Everything seemed fine, there is connectivity and things operate, but a few days later we noticed that some network transfer activities are slow. There are no errors or log entries showing on the new switch or the old one, but the low throughput is persistent.
All ports show 1G Full duplex as they should, but what I see when I test is that traffic tests look almost asynchronous when passing switch boundaries with normal read speeds and slow writes. Reversing the direction of the test hosts I get slow reads and fast writes so it seems to 'stick' to one side of the traffic path. Testing the same equipment against differente targets without the switch boundary crossing does not show the problem. All Intra-switch tests look good (gig switches transfer near a gig and 100 switches near 100), but the moment there is a crossing things behave strangely regardless of the target (new switch is center backbone with most hosts, but does no routing). Network layout is essentially a T with everything radiating from the new switch. I can eliminate the old switch soon, but I still need to resolve the problem with the crossing to the other switch.
Everything seems to point at the inter switch links. One is a patch cable under two feet, and the other is a dedicated fiber site link. We had the vendor confirm that the site link showed no issues, but having the same symptoms on both links makes me suspect the switch has something odd happening..
I checked for duplex issues first, but didn't find any. I flushed the arp caches in all of the switches (3 total) and all of the computers as well, but the problem persists.
Could this be an STP issue ? If so how can I set this switch as the STP root and force a refresh..
Any help would be greatly appreciated.
