BL C-GBE2 Issues

[Jayachandran_2]

I have a mixed netowrk which uses Cisco3750T's which are connected to CGBE2's on ports 21 n 22.. I see a lot of discards on those interfaces on all the swithces of HP.
I am quite foxed as I have checked everything.. I am attaching a TSDUMP of one of the switches.. anyone who helps will be highly appreciated as HP themselves are not helping us..

[Greg Healy]

From the TSDUMP it looks like the discards on ports 21 n 22 are solely attributed to "dot1PortInDiscards".

From GbE2 Command Reference Guide.

"dot1PortInDiscards = Count of valid frames received which were discarded (that is, filtered) by the forwarding process"

As these ports are tag enabled dot1Q tagged packets will be processed. Non tagged packets will be associated to each ports PVID (VLAN 1 as per the TSDUMP)

Assuming that you have configured VTP Transparent mode on the Cisco Switches, then you cannot enable VTP pruning.

From Cisco UniverCD

"VTP Pruning
VTP pruning increases network available bandwidth by restricting flooded traffic to those trunk links that the traffic must use to reach the destination devices. Without VTP pruning, a switch floods broadcast, multicast, and unknown unicast traffic across all trunk links within a VTP domain even though receiving switches might discard them. VTP pruning is disabled by default."

"....VTP pruning is not designed to function in VTP transparent mode......"


Assuming there are additional VLANs defined within the Cisco switches that are not defined within the GbE2 switches. The Cisco switches may be presenting valid frames to the GbE2 switches with an unknown VLANID, the GbE2 switch should filter out (discard) those packets.

This leaves the "dot1PortInDiscards" port counters reporting all dot1Q frames received by those ports that cannot be matched to a VLAN defined within the GbE2 switch.

Possible Solution : Try defining the missing VLANs without associating any ports.

Otherwise accept this as normal reporting behaviour.