Catalyst 3020 as pass-though?

Answered Question
Apr 3rd, 2008

I have not found a way to do this but I was wondering if I can configure one of the ports on a Catalyst 3020 in a blade server (HP in my case) as a pass-though port to one of the internal NIC's? Anyone know if this is possible?

We do not have the pass-though modules, just need one port to do this.

I have this problem too.
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Correct Answer by mslavin about 8 years 7 months ago

Hi Steve,

Just wanted to make sure, as the term pass-thru seems to be getting used in different ways by different people nowadays :-). In this case, the answer is that I do not know of a way to make a switch act like a physical pass-thru. The best that can be done is to dedicate a server port and an uplink port to a single common VLAN, or making use of PVLAN as noted before, to isolate traffic flows.

On that note, if you absolutely have to have physical isolation such as you desire, then a physical pass-thru is the only option.

I can tell you that I've worked with customers that have used blade switches for heartbeats, so I'm not so sure you need this complete isolation, but that is certainly an individual judgment call.

Thanks, Matt

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mslavin Fri, 04/04/2008 - 07:05

Hi Steve.

The 3020 is a switch with a fixed number of downlinks and uplinks, so it is definitely not a simple pass-thru. The uplinks can be used for any purpose, whether it be for EtherChanneling together or as individual ports for individual connections to various networks/devices.

Can you tell me what you're goal is with this single connection between the server and the upstream?

You may be able to do this with simple VLAN separation, but it may not be straight forward if you are using the same VLAN for this single server and other servers in the same enclosure. I believe the latest version of code for the 3020 also supports full PVLAN, which may be another approach, but would need to better understand you're ultimate goal.

Thanks, Matt

sdrossen2 Mon, 04/07/2008 - 08:01

Matt,

I have the switches setup in a VTP domain and I don't want to add a new vlan to the VTP domain. I was wondering if I can replicate the function of the pass-thru blade that HP makes or should I buy the pass-thru.

The reason I want it to be separate is this is for a heartbeat network that needs to run on a separate infrastructure that runs on its own switched network. I could just make a layer 2 only vlan for this one blade center but the 3020's are VTP and don't want to mix the two networks.

Steve

sdrossen2 Mon, 04/14/2008 - 07:11

yes, that this the module I am talking about. I want to replicate that functionality on a single port on the Cisco 3020.

Correct Answer
mslavin Tue, 04/15/2008 - 05:46

Hi Steve,

Just wanted to make sure, as the term pass-thru seems to be getting used in different ways by different people nowadays :-). In this case, the answer is that I do not know of a way to make a switch act like a physical pass-thru. The best that can be done is to dedicate a server port and an uplink port to a single common VLAN, or making use of PVLAN as noted before, to isolate traffic flows.

On that note, if you absolutely have to have physical isolation such as you desire, then a physical pass-thru is the only option.

I can tell you that I've worked with customers that have used blade switches for heartbeats, so I'm not so sure you need this complete isolation, but that is certainly an individual judgment call.

Thanks, Matt

sdrossen2 Tue, 04/15/2008 - 06:40

Thats what I thought but felt it was worth asking. I am for putting the heartbeat vlan on the main production infrastructure but the DBA's say no and its there call so they get to buy the extra hardware dedicated to a heartbeat network.

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