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New Member

RSPAN across VTP domains

Hello,

Since a picture says a thousand words. Here is my basic setup:

http://www.flickr.com/photos/31154535@N07/4690608002/sizes/l/

What I would like to do is capture vlan 222 on the closet siwtch in the diagram in VTP Domain A and send that traffic to a port on the switch in VTP Domain B. Sounds simple but I have never used RSPAN before and dont even know if this will work. The SVI for vlan 222 is on the core switch. Also if I have several closet switches (and I do) and I want to do the same with them does that change the solution if there is one?

Thanks for any help and advice you can give.

P.

5 REPLIES
New Member

Re: RSPAN across VTP domains

Thanks Andrew,

Good links.

Accoring to the documentation there are two things that strike me under RPAN guidelines:

As RSPAN VLANs have special properties, you  should reserve a few VLANs across your network for use as RSPAN VLANs;  do not assign access ports to these VLANs.

Access ports (including voice VLAN ports) on the  RSPAN VLAN are put in the inactive state.

In my case vlan 222 is the voice vlan. In fact this project is for capturing RTP and SIP for a voice aquisition server. The first point states RSPAN VLANS should not have ports assigned to that vlan. Perhaps I am not underatnding this, but does that mean if i have the command switcport access vlan 222 on s port that RSPAN wont work?

And point two I dont understand what they mean by inactive state

Thanks again,

P.

Re: RSPAN across VTP domains

Did you read all 3 links - all the way thru? You pointed out:-

- As RSPAN VLANs have special properties, you  should reserve a few VLANs across  your network for use as RSPAN VLANs;  do not assign access ports to these VLANs.

- Access ports (including voice VLAN ports) on the  RSPAN VLAN are put in the  inactive state.

Read Link -

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.1_19_ea1/configuration/guide/swspan.html#wp1081130

The RSPAN VLAN is used the TRANSPORT the captured VLAN traffic from the source to the destination. if you use an existing VLAN - you will break it.

HTH>

New Member

Re: RSPAN across VTP domains

Andrew,

Thanks again for your help. I did not read all three documents. I really just would like to know if I can do what I want to do, and then I will read all three if necessary, but from the little bit I did read, it looks like I cant use RPAN for an exsisting voice VLAN.

I will just have to run cables to the aquisition server from the closet switches.

Thank you!

P.

Cisco Employee

RSPAN across VTP domains

Hi


Here are the answers to your concerns:


1.  We can do the RSPAN across VTP domains without any problem because in RSPAN configuration, we make RSPAN vlan just for the     data to be sniffed     and carry the traffic on that vlan across to the other switch . And we make the same RSPAN vlan on the         other switch as well, so it does not create a problem if we have multiple VTP domains.

2. The inactive state means that if you put an access port in RSPAN vlan , it will go in inactive state because RSPAN is not              considered as regular access vlan on the switch, therefore the ports go into inactive state. So if you are sniffing the vlan 222

then you can put the port in the vlan , but will not make vlan 222 as the RSPAN vlan.

Hope it helps.

Prabhdeep Nijjar

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