creating dlsw peers

[axfalk]

Can someone please point me out to the doc dor configuring dlsw peers. Also, do I need to create a loopback interface in the MSFC (Cat-6506) if it's one of the peers?

Thanks.

[Georg Pauwen]

Hello,

for the MSFC, since it does not have physical ports, you indeed need a Loopback interface for DLSw peering.

Check the following document for detailed information on how to configure the peers:

Configuring Data-Link Switching Plus

http://www.cisco.com/en/US/partner/products/sw/iosswrel/ps1831/products_configuration_guide_chapter09186a00800d9826.html

Regards,

GP

[Richard Burts]

The link that Georg posted is good and should include what you need to know to configure DLSW peers.

While a loopback may be desirable I do not think it is required. What is required is an IP address that is reachable from the remote device. I think it should work whether it is loopback or vlan.

HTH

Rick

[axfalk]

Thank you for your reply. we happened to have several different Vlan's that have hosts on them that generate the SNA traffic. do i need to define a bridge-group on every vlan interface or can i create a loopback interface, define the bridge-group on it and "funnel" all the vlan's sna trafffic through it?

Thanks again

[Georg Pauwen]

Hello,

wether or not you use the Loopback interface as the peer address, all the VLAN interfaces that have hosts connected that generate SNA traffic will need to be member of the bridge group.

HTH,

GP

[axfalk]

Thanks for shedding the light on how to use DLSw in conjunction with VLAN's. Unfortunately, that part is not covered in the DLSw docs, or at least I was not looking at the right docs. So, if the peer local router has 4 VLANs that happen to have the devices that generate SNA traffic, the peer remote router would have to have 4 separate remote peer connections defined to these 4 VLANs?? Currently, these 4 VLAN's are already defined as part of a bridged-group since the SNA traffic is being bridged to another router. The reason for DLSw is that we will be pushing the SNA traffic across WAN to another router that, in turn, will send it to the MainFrame.

Thanks again

[Richard Burts]

If you have a router with 4 VLANs which carry SNA traffic the remote router will not need 4 remote peer statements. It will need only a single remote peer statement. (The router peers with the router not with the VLAN.) The remote router will encapsulate the SNA using DLSW and send it to its peer (router). When the DLSW packet it received, the router will de-encapsulate it and forward the SNA frame based on the destination MAC address.

HTH

Rick

[axfalk]

Thanks for the clarification. What are the trade-offs in establishing a peer connection with a loopback int vs a vlan int?

thanks a lot again.

[Richard Burts]

The primary advantage is that you avaoid dependence on a single interface. If you were to peer with the VLAN address (of a single VLAN) and for some reason that VLAN became unavailable then you would lose the peering relationship with the entire router and potentially affect traffic to the other three VLANs. But if you peer to the loopback then as long as the loopback is available you will maintain the peering session and be able to get to any available VLAN - even if some VLANs have become unavailable.

HTH

Rick

[axfalk]

Thanks - that has been very educational and helpfull. I just have a quick follow-up question if you do not mind. currently, we have bridge-group 2 defined on all our vlans, so that the SNA traffic could be bridged to a local router. Can we bridge some vlans' SNA traffic to a local router (via one bridge-group) and send the other vlans' SNA traffic to a remote router via DLSw (via another bridge-group) or is it all or nothing? Thanks again.

[Richard Burts]

I have not done what you are asking so I can not answer it from experience. But based on having done DLSw in a number of places and on my understanding of the documentation, I believe it should work fine to have one bridge group which will bridge SNA to a local destination and to have another bridge group which will send SNA to a remote router using DLSw.

When you configure DLSw over Ethernet you use the dlsw bridge-group command to associate a particular bridge group with DLSw. I do not see why it would be a problem to have another bridge group (which would be on different interfaces) and would bridge SNA to local destinations. Any end station would have to be in one bridge group or another but can not be included in both. As long as your topology and traffic pattern fit this, I believe you could have two bridge groups without a problem.

HTH

Rick