Mpls traffic engineering

[carl_townshend]

Hi guys

ive been doing some reading on mpls traffic engineering.

They talk about the ingress router using rsvp and setting up tunnels to the egress router.

are they really tunnels? Or just predetermined label switched paths?

Does your typical ISP like BT in the UK use this kind of configuration on their mpls network ?

Is the main purpose of mpls te to use all links in the network or for other things ?

Cheers

[balaji.bandi]

As per my understanding i know - Most of the SP/ISP take advantage of MPLS of their CORE network to delivery the Service using best of their infrastructure and Links - it's a very big subject to understand deeper, and also good to simulate some MPLS Labs like SP network to get understand how that works.

MPLS uses  IP tunnels 

how TE to be achieved based on requirement and design.

Good start :

https://www.cisco.com/c/en/us/td/docs/routers/crs/software/crs_r3-9/mpls/configuration/guide/gc39crs1book_chapter4.html

[MHM Cisco World]

are they really tunnels? Or just predetermined label switched paths? NO really tunnel, it predetermined label, the TE header router send RSVP and each hope reply with it Label, 
the TE header then use this label to forward traffic through MPLS

Is the main purpose of mpls te to use all links in the network or for other things ? 
I dont understand exactly your Q but 
if MPLS run OSPF and there are many link to same destination, the OSPF calculate the best path and ignore other path, this loss of resource, so solution using TE which you can config specific criteria like BW to select link i.e. run additional SPF to calculate the path.

[Harold Ritter]

Hi @carl_townshend ,

> are they really tunnels? Or just predetermined label switched paths?

The tunnel is a logical interface that is used to instantiate the label switch path.

> Does your typical ISP like BT in the UK use this kind of configuration on their mpls network ?

Many service providers use MPLS TE.

> Is the main purpose of mpls te to use all links in the network or for other things ?

The are many reasons for deploying MPLS TE. It might be to optimize the utilization of the links in the core network or to offer differentiated services to customer paying a premium, just to name a few.

Regards,

[MHM Cisco World]

I will share lab for the RSVP message showing how tunnel is build 
hope share it tonight