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How to set MPLS Labels?

I have a C2600 router. I wish to take packets entering from one link (ex. WAN link from ISP#1) and set them with a specific MPLS label, and take packets entering from another link (ex. WAN link from ISP#2) and set them with a different MPLS label, before sending the packets out the LAN interface.

I cannot quite find the correct combination of IOS commands to achieve this. Can anyone please offer some pointers?

13 REPLIES
New Member

Re: How to set MPLS Labels?

Use class-map's, policy-maps and service-poicies. You'd define the traffic in class-maps, apply the MPLS to the defined traffic on the policy-map and apply that policy to an interface. Check up on MQC on www.cisco.com

Re: How to set MPLS Labels?

Ok, now how's that? The only MPLS option that MQC offers is the ability to change the experimental bits, for the purposes of some QoS strategy. But looks like Mr. Copeland doesn't want to change the experimental bits, he wants to change the actual label.

New Member

Re: How to set MPLS Labels?

I guess your right. You need an ATM switch from Cisco. I saw the mpls in the policy map, but never hit a question mark after it to see the ex value.

Re: How to set MPLS Labels?

I don't believe there is a way to set explicit LSP's in the way you are describing, at least not in any publicly available IOS (12.2[4]T or 12.0[19]ST). You can create explicit LSP's in JunOS, so if that's what you really want to do, I recommend getting some M-5's.

The problem is that in dynamic labeling you may recall that whether you use LDP/TDP or RSVP-TE, it's actually the downstream LSR that determines what labels will be used. So the C2600 in question has no power to determine what labels it will push. You might be able to play some games with TE tunnels combined with PBR, but even then, I have the gut feeling that something will break. Like I said, IOS does not offer the feature of allowing you to explicitly assign the labels you want to assign (unless you want to use a MPLS label range, but even then, it would still be dynamically assigned, just using a smaller range).

New Member

Re: How to set MPLS Labels?

Thank you for your response. I wasn't able to find a way to do this either, however I thought I may have missed something. You have validated that what I want to do isn't possible with Cisco IOS. I noted the other reply about ATM switches, but these are not present in my environment.

New Member

Re: How to set MPLS Labels?

Hi,

I have a C4500 and a C7505 router. They are not directly connected, but are directly linked by a tunnel, through a production network. I am trying to get them to exchange label bindings via LDP.

I am using basic hello discovery. When debugging, I realise that they have "discovered" each other through the hello messages received via the multicast address. However, TCP connection always fails. Has anyone encountered this problem before?

Or does anyone know the reason for this?

Thanks a lot!

New Member

Re: How to set MPLS Labels?

I would like to help, but I am confused on what you are wishing MPLS to accomplish. Are you attempting to implement MPLS VPNs or are you looking to use MPLS to perform some type of TE on you LAN? Also are your WAN interfaces running LDP and are your ISPs LDP neighbors? In other words are you purchasing some type of MPLS service from your ISPs? What do you hope to accomodate by inserting a different label?

If you wouldn't mind responding I'd probably be able to provide some recommendationds.

CC

Re: How to set MPLS Labels?

Well there's an interesting statement right there: "...are your WAN interfaces running LDP and are your ISPs LDP neighbors? In other words are you purchasing some type of MPLS service from your ISPs". I take it you're referring to the RFC2547 carrier-of-carriers [CoC] model, because after all, why else would you want to establish LDP sessions with your provider? I frequently hang out at Nanog, and as far as I know not a single provider in the world offers commercial CoC at this time. The two providers that were fairly close to doing so are Global Crossing and Level3, and let's just say that both of them have more important things on their plate, like avoiding bankruptcy like Level3, or getting out of bankruptcy without excessive damage like Global. Neither one seems to be particularly interested in developing more high-end services at this time, nor should they be.

New Member

Re: How to set MPLS Labels?

I realised my earlier problem was due to the LDP identifier (router-id). I just had to set it to an interface's value and it worked fine.

Thanks anyway!

New Member

Re: How to set MPLS Labels?

One other thing, if you are attempting to perform TE label imposistion it is not supported on the 2600 series platform. It support begins on the 3640 and is also supported on the 3660, 4500, 7200 and 7500.

New Member

Re: How to set MPLS Labels?

Hello,

The big question here is why? If you 2600 is an edge MPLS device with its LAN interface the only connection into the MPLS cloud. Labels are base on FEC and are assign by the upstream router facing the 2600. If you want packets destine for ISP1 to take a different path through the MPLS cloud then ISP2, then implement MPLS-TE.

Don Lakey

Re: How to set MPLS Labels?

Exactly.

New Member

Re: How to set MPLS Labels?

Hi,

From the docs around, they demonstrate how to implement Diffserv over MPLS using E-LSPs, that is setting the EXP bits and using class/policy maps.

But how about for MPLS for ATM? The way to implement DS over MPLS will be through L-LSPs whereby the COS is determined by the label and the drop precedence is determined by CLP.

But, I can't seem to find docs on how to implement L-LSPs for ATM-MPLS networks. Anyone can help?

Thanks a lot in advance!

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