High In-Discard shown on CAT6506 CATOS

Unanswered Question
Mar 9th, 2009

Hi,

I have seen high in-discard shown on the switch. The port is a trunk port and it is in blocked state. Any idea why it has such high discard?

TP4L2-BS4> (enable) show mac 3/24

Port Rcv-Unicast Rcv-Multicast Rcv-Broadcast

-------- -------------------- -------------------- --------------------

3/24 361014401 2898449 4768726

Port Xmit-Unicast Xmit-Multicast Xmit-Broadcast

-------- -------------------- -------------------- --------------------

3/24 0 16220 0

Port Rcv-Octet Xmit-Octet

-------- -------------------- --------------------

3/24 112818146741 2332265

MAC Dely-Exced MTU-Exced In-Discard Out-Discard

-------- ---------- ---------- ---------- -----------

3/24 0 - 325181908 0

Port Last-Time-Cleared

TP4L2-BS4> (enable) show trunk 3/24

* - indicates vtp domain mismatch

# - indicates dot1q-all-tagged enabled on the port

Port Mode Encapsulation Status Native vlan

-------- ----------- ------------- ------------ -----------

3/24 on dot1q trunking 1

Port Vlans allowed on trunk

-------- ---------------------------------------------------------------------

3/24 1-1005,1025-4094

Port Vlans allowed and active in management domain

-------- ---------------------------------------------------------------------

3/24 1-12,14-18,20-25,30,50,60,70,88,99-101,200,500

Port Vlans in spanning tree forwarding state and not pruned

-------- ---------------------------------------------------------------------

3/24

TP4L2-BS4> (enable)

TP4L2-BS4> (enable) show spantree blockedports

T = trunk

g = group

Ports VLANs

----- ----------

3/23 (T) 1,2,3,4,5,6,7,8,9,10,11,12,14,15,16,17,18,20,21,22,23,24,25,30,50,60

,70,88,99,100,101,200,500

3/24 (T) 1,2,3,4,5,6,7,8,9,10,11,12,14,15,16,17,18,20,21,22,23,24,25,30,50,60

,70,88,99,100,101,200,500

Number of blocked ports (segments) in the system : 66

TP4L2-BS4> (enable)

I have this problem too.
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jorge.calvo Tue, 03/10/2009 - 17:00

Hi,

In first place a physical problem should be discarded by checking or replacing the cable.

Then, some things that could be checked are:

1. Possible duplex mismatch?

2. Is the other side trunk using dot1q. If it is using ILS the trunk will be up but the errors will increase.

3. Is the MTU size the same on both ends?

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