Traffic Flow over MPLS TE

Unanswered Question
Jun 25th, 2010


Please refer the attach sample netwok diag.

I would like to ask few Question related to MPLS TE .

1] MPLS TE is only used to flow traffic as we requried ? If  Yes,  Then this option is available in IGP Protocol then why MPLS TE is preffer or used ?

2] In Tunnel configuration if we used multiple path option both explicit path & Dynamic path , Then whether it will load balance with Explicit & Dynamic Path  with single tunnel if NO then why two potion path is used ?

3] Two Tunnels are configured with different path option , So it will load balance & Only FRR used for reroute if the tunnel failed.

4] If i am having three links which is used to reach destination, an each link is having 1 MB of link & I requried total 2.5 MB to transfer data. So whether i can use single tunnel to achive the requried bandwidth.

6] Can sone one brief about Priority ? How it work ?

7] In attach diag , If i want to use  PE-1 AS1 -- P1 AS1 -- PE2 AS1    &   PE-1 AS1 -- P2 AS1 -- PE2 AS1 to load balance &


  PE-1 AS1 -- P3 AS1 -- PE2 AS1 path uses as a backup then how may tunnel need to configured.


Chetan Kumar


Chetan Kumar

I have this problem too.
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Giuseppe Larosa Fri, 06/25/2010 - 10:01

Hello Chetan,

1) with MPLS TE you can move traffic over multiple hops over a deterministic pre-established path signalled by RSVP TE compare to use PBR on each router hop

2) when multiple path options are present they act as primary and secondary path not in load balancing there is a preference and the lowest is preferred.

if the primary path fails after a link failure (for example because it is an explicit path)  the secondary path may be used instead of attempting to use another tunnel or an LSP LDP

3) see above

4) MPLS TE performs call admission control only when the tunnel is setup you can put 3 Mbps of traffic over a tunnel with 1Mbps signalled RSVP bandwidth

6) if multiple tunnels are in competition to be setup during call admission control one tunnel can be preferred and it is setup first if remaining resources are enough also the other one is setup

7) two PE tunnels with each  tunnel with two options each , or 4 tunnels using FRR to define one backup tunnel for each primary tunnel

Hope to help


Chetan Kumar Ress Fri, 06/25/2010 - 10:36

Hi Giuslar

Thanks for you explanation .

Can you brief what you said , I am not able to understand exactly ?

7) two PE tunnels with each  tunnel with two options each , or 4 tunnels using FRR to define one backup tunnel for each primary tunnel.

As per my Understanding :

Frist Way :

1st Tunnel :  Two Option : 1st RED line & Blue Line .

2nd Tunnel : Two Option : 2st RED line & Blue Line.

Second way : using FRR

Please can you define is more to understand.

As per me  Three Tunnel will be Primary & Using FRR  to define backup tunnel for each primary tunnel and FRR Tunnel need to create in                      P1-AS1 and P3-AS1.


Chetan kumar


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