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New Member

Traffic selection

I created one LSP on the headend routeur.

I want to reduce the part of trafic in this LSP. So, I want to do a traffic selection on my headend router based on the source address and source port.

I can't find the mean to do this traffic selection.

The only mean I found is to do class-based tunnel selection with the following command :

tunnel mpls traffic-eng exp 5

How can I do to do my trafic selection according to address pool and/or port field?

Cisco Employee

Re: Traffic selection


Do you use MPLS Traffic engineering in your network? If so, then you could either setup parallel tunnels and do load sharing (cef even allows to do unequal bandwidth loadsharing) or you can use PBR in a plain MPLS environment, i.e. no MPLS VPNs. If MPLS VPNs are involved, the whole story gets more complicated, but can also be done.

It really depends on what exactly you would like to achieve and what your network looks like. Can you provide more detailed information?

Regards, Martin

Re: Traffic selection

You will not be able to map traffic from a combination of source address and source port, as its not a valid FEC.

But to somewhat achieve the same you can try to step a little back and think of the managed CPE concept, where in you would be able to classify the ingress traffic entering the ingress PE. Here you can use your source address/port combination to map it to the appropriate PREC/DSCP, and the same gets mapped to the appropriate EXP value when it enters the PE, and there onwards you have the class based tunnel.

But the drawback is you can derive only as many number of combinations as the EXP values, which is 8. Which is true for any other traffic as well.

I believe this can be the closest in terms of putting a certain traffic with source address/port combination onto an LSP.



New Member

Re: Traffic selection

Thanks for your responses.

Actually, here what I would like to build:

I have two LAN which are connected to a PE routeur. I'm using MPLS-TE to dynamically create two LSP (LS1 and LSP2) according to traffic charge . I prioritize LSP1 before LSP2

in putting different priority coef.

So, now, I want to match trafic from LAN1 with LSP1 and trafic from LAN2 with LSP2.

I saw it could be possible with static method :

ip route Tunnel1

Martin, wrote me it could be possible in using policy-based routing? Which is the difference between using static method before PBS to make FEQ?

Re: Traffic selection

I am not sure what needs to be achieved.

In the original post you mentioned wanting to do a source address/port based selection.

(port : I have assumed higher transmission ports and not physical ports)

But using this static route you would be doing a destination based selection.

So all traffic going towards that subnet would go via the tunnel 1.

Using policy based routing you cannot influence VRF traffic. Only normal transit traffic.

To use policy based routing for VRF, you will have to create additional loopbacks per PE and manipulate the RT values received to point to this next-hop(new loopbacks created). You will be creating tunnels as usual with a static route pointing at each end to this new loopback via the tunnel.

So to sum it up, what needs to be achieved the appropriate solution would depend on that.



New Member

Re: Traffic selection

Thanks for your very clear response, I became to understand a little more how work traffic selection.

So the only mean to do a traffic selection is

to do a source based selection in using static route.

Or, do a class based selection in using class-based tunnel selection. I must use PBS in this case.Is it right?

But in case of, i need to use 8 values of EXP field to differenciate trafic type (mapping EF, AF.. class) for Qos and in a same case I want to do a source based selection (i.e : map trafic from LAN1 in LSP1, map trafic from LAN2 in LSP2...), how can I proceed?

Re: Traffic selection

To sum it,

1) For ATOM you can use Atom Tunnel selection feature to select the right tunnel for your ATOM treating it like a virtual leased circuit.

2) For all the traffic going to a certain destination from a PE you can use "Class Based Tunnel Selection"

3) For all traffic from a certain VRF and going to a destination PE you can use the RT manipulation with a Tunnel selection with static route.

4) options 1, 2 and 3 are destination based for source based you have only option of the EXP values, like you can map your actual source address/port to a certain EXP and then map that EXP onto an LSP using the "Class Based Tunnel Selection" But you have only 8 classifications available for the whole PE.

5) This option gives you the flexibility to assign a VRF to incoming traffic based on source IP address "VRF selection using PBR"

You can choose what you feel is appropriate from the above as you know the objective.



New Member

Re: Traffic selection

Thank you very much for all your responses Swaroop.

Traffic selection appear to be much more difficult than what I thought.

So I still need some clarifications:


In the case or I have two LAN (LAN1-> and LAN2-> connected to PE1. I created LSP1 which link PE1 and PE2. So If a want that only trafic from LAN1 use LSP1, I must use the next command :

ip route Tunnel1

And If a want that ALL traffic use this LSP, I can use the next command :

tunnel mpls traffic-eng autoroute announce.

Is it all right?

2) Can I use the command "ip route" (static method) to reduct utilization of my LSP (source based differenciation) and in a same time use the command "tunnel mpls traffic-eng exp" (class based tunnel selection) in order to reduct trafic of the LSP according to its type.

3) Does the last option you explain me "VRF selection using PBR" allow to use CBTS in a same time?

Re: Traffic selection

1) if the LAN 1 to LAN 2 traffic is not withing a VRF you can do it using the ip route method.

2) you can use the ip route and CBTS together if the traffic going via the 2 tunnels is not to the same destination.

3) I havent tried this, but logically you can.May be you can lab it up and let us know.



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