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jayd2k
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[WORKAROUND] VPLS-LDP/RSVP-TE tunnels simultaneously?

Tue Aug 05, 2014 10:09 am

Hi *,

I'm having some trouble understanding how to operate VPLS and TE tunnels in parallel between a pair of routers.

I'd like to operate multiple TE and VPLS tunnels in parallel between a pair of routers. Right now when creating a VPLS tunnel, a pair of TE tunnels is automatically generated for bi-directional transport. If ever there are any existing TE tunnels on the head and/or tail-end router that are matching the transport address of the respective VPLS tunnel, those will be used instead.

That means that all the bandwidth constraints in-place for those TE tunnels, automatically also applies to the VPLS tunnels that are running on top. Since the TE tunnel pair is selected automatically during initialization phase it's somehow impossible to predict which TE tunnels are going to be used used for transport.

My question: How to operate multiple VPLS-LDP tunnels in parallel to RSVP-TE tunnels between a pair of routers w/o having the VPLS tunnels being randomly placed on any of the existing TE tunnels?

During my research I used to came across a post where someone suggested to just use a different set of loopback addresses for the TE tunnels as well as the respective VPLS tunnel to 'steer' the tunnel onto a specific pair. I've tried this but even the TE tunnels wouldn't come up. The loopback addresses are configured and are being advertised using OSPF within the backbone area.

Of course, using one set of loopback addresses per VPLS tunnel would produce a massive overhead in regards to IP address management. However, as long as "preferred path selection" wasn't implemented with ROS I don't see any way to make it work). It was confirmed by the MT support that preferred path selection wasn't implemented yet (!).

I'm attaching a diagram that hopefully helps you guys understanding what is outlined above.

I consider this a valid use-case for an MPLS domain to run multiple VPLS and/or TE tunnels in parellel between two routers.

Now I'd like to know how you guys are dealing with this? It's a valid use case which IMHO renders the platform useless if it can't be accomplished. However, if you think that running multiple L3+L2 tunnels in parallel between two routers isn't a valid use-case at all please let me know.

Thanks
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Last edited by jayd2k on Fri Aug 29, 2014 9:48 am, edited 2 times in total.
By 2016 total internet traffic will be 3x 2011
 
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jayd2k
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Joined: Tue Sep 10, 2013 6:46 am
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Re: Operating VPLS-LDP and RSVP-TE tunnels simultaneously?

Thu Aug 07, 2014 4:00 am

Guess I'll have to work around things then.

Well, establishing TE tunnels between different pairs of transport/loopback addresses is working. I had a twist on my lab gear that as I figured last night.

In regards to VPLS - the workaround is to establish VPLS tunnels using the main loopback addresses - here 10.99.238.1 (R1) and 10.99.238.3 (R3) respectively.

To apply traffic engineering (incl. LSP selection + backups) one has to pre-create TE tunnels for transport between 10.99.238.1 and 10.99.238.3.

Keep in mind that in the end ALL VPLS tunnels between R1 and R3 will use these tunnels as a transport. Meaning, all constraints (e.g. like guaranteed bandwidth, LSP selection and rate limiting) will apply to them (shared queue for each direction). Individual rate-limiting of VPLS tunnels can be achieved by using connection markers and simple queues. Don't place any additional TE tunnels for L3VPN on this transport but use separate loopback addresses instead as illustrated in the diagram (10.100.0.1 <-> 10.100.0.3 etc.).

This approach isn't flexible and comes with an administrative overhead. I consider *MPLS preferred path selection* as (e.g. as implemented by CISCO) a mandatory feature in order to fully utilize the flexbility that MPLS offers. Preferred path selection allows for pushing VPLS transport across a preferred set of TE tunnels:
To configure routing by explicitly selected tunnels, use either the MPLS preferred-path tunnel selection option under pseudowire-class or the route-via option under the virtual-ethernet transport configuration. At first release, MPLS preferred-path tunnel selection is supported; the route-via option will be supported in a future release.
Source: http://www.cisco.com/c/en/us/solutions/ ... 02184.html

If anyone knows a better way to achieve this or perhaps even a workaround on how to force VPLS tunnels to utilize a specific pair of TE tunnels for transport, please let me know.
By 2016 total internet traffic will be 3x 2011

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