From: Troy Edington (TEdington@xxxxxxxxxxxxx)
Date: Fri Jun 08 2001 - 01:01:22 GMT-3
Hello group,
I am having a problem with a catalyst 6509. Specifically the problem is
that traffic seems to be leaking between two logically separated VLAN's. I
run my Sniffer on a span port with one source port in VLAN 10 pointing to
it(A Solaris box). I am spanning transmitting traffic only, just to verify
that it is the switch transmitting and not feedback from the one machine.
Here is specifically what I see.
Vlans involved
VLAN 10 10.80.10.0/24
VLAN 30 10.80.30.0/24
This machine has an IP of 10.80.10.20 (VLAN 10)
I configured the Sniffer to ignore all packets with this IP in it. What I
see was kind of amazing
Immediately I see lots of traffic from other VLAN 10 machines going to this
port. This is not broadcast or multicast traffic but unicast traffic For
example 10.80.10.30 to 10.80.10.40, etc etc shows up in the Sniffer (Both DS
Pro and Snoop on Solaris)
If that wasn't bad enough I see an occasional packet from a totally separate
VLAN 30 10.80.30.18 10.80.30.22 Now this is local traffic what the hell is
it doing in VLAN 10
I understand from Cisco and please someone correct me if I am wrong. When a
packet hits the back plane it is by default sent to every port and it is up
to the CPU to instruct all ports except the correct destination port to drop
the traffic. There can be leakage if your back plane and/or CPU is heavily
utilized. Well I am at 4% CPU utilization and throughput utilization is
low. (I am only using 48 Fast Ethernet ports on the 6509)
I am running the following
ver 6.1a
I am only running Layer 2 on the switch no MSFC routing (The hardware is
installed but we are not using it)
I have tried sniffing other ports with the same result
no trunking is going on anywhere
no port-channeling anywhere
Everything runs fine and the network is up but I would like to know what is
going on. Any ideas anyone ?? I searched for bugs and solutions on the CCO
with not much luck.
Thanks in advance for any suggestions
Troy Edington, CCIE #7190
Network Engineer
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