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VLAN ifInOctets/ifOutOctets on 3550-24 EMI

I am setting up some bandwidth monitoring on a 3550-24 with the latest EMI image installed. The problem I have run into is monitoring ifInOctets and ifOutOctets on VLAN interfaces. Octet counts on physical interfaces are correct, but the counts on the VLAN interfaces are inaccurate

On this switch:

ifindex 1-24 : fa0/1-fa0/24

ifindex25-26: ge0/1 - ge0/2

ifindex 27: null0

ifindex28-32: Correspond to VLAN1 - VLAN5

Vlan 1 Native Vlan (172.31.254.x)

Vlan 2 Server/Wks (172.31.1.x)

Vlan 3 Internet (172.31.2.x)

Vlan 4 Wks (172.31.3.x)

Vlan 5 Wks (10.10.1.x)

From my testing here is what I found.

1) Interface fa0/1 (vlan2) is connected to the inside interface of a pix515

2) if I start a large download, I monitor the ifinoctetes/ifoutoctets of the pix firewall ( and get accurate data

3) I monitor the same stats for fa0/1 (physical port on the 3550) and I get the same statistics as what i am pulling from the pix

4) The workstation that is doing the download is on Vlan 5 (

5) If I monitor the physical port the workstation is attached to, I get the same statistics as the pix and fa0/1

6) if i monitor the stats for both Vlan 3 (internet) and Vlan 5 (wks), their is less than 1 percent of the octet count as represented by monitoring the physical port

I have tried this on two 3550 switches and have come up with the same problem.

For example. If I monitor the "PHYSICAL" port (fe0/5) with the following MIB, I get accurate data.



But, If I monitor the VIRTUAL port (VLAN5), I get inaccurate octet counts.



To summarize:

Octet counts on physical ports are accurate.

Octet counts on virtual (VLAN) ports are inaccurate

If I track data coming in on a physical port (Vlan3) and route it to another port (vlan5). I can see the accurate octet counts on the physical ports, but do NOT see the octet counts reflected on the virtual VLAN ports.

Has anyone run into this.....



Re: VLAN ifInOctets/ifOutOctets on 3550-24 EMI

There is a bug related to this. The correct values for the count may not be shown as per this bug. Your issue may be due to this. You can go to the bug toolkit and search for the bug.

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