[c-nsp] RSVP-TE was (no subject)

[adamv0025 at netconsultings.com]

> emmanuel manoni
> Sent: Tuesday, April 7, 2020 5:42 PM
> 
> Hi, I'm a Network Engineer in a Carrier Network, recently I have been
> learning MPLS TE. I have some questions regarding MPLS TE deployment in
> IOS XR.Kindly help
> 
> 1.Using forwarding-adjacency as a method of distributing traffic into the
TE
> Tunnels, is it possible to do unequal cost load-balance?Which commands I
> use in IOS XR??
> 
I guess if you put different IGP metric on each tunnel and then enable
unequal cost multipath (UCMP) load-balancing, subject to testing.  


> 2.Again,if I'm using forwarding-adjacency with two Tunnels with the same
> destination and I have setup equal metric in those Tunnels,how will the
> router load-balance the traffic into those Tunnels?will it loadbalance the
> traffic equally between the Tunnels?
> 
Yes it will use the same load-sharing algorithm like it would if you had two
physical links to the tunnel destination.
My advice,
Be careful with "forwarding-adjacency" -as it makes the head-end advertise
the tunnel in IGP to other nodes like it was a standard link -which might
really complicate your traffic flows if you're not careful.
Safer option is to use "autoroute-announce" -which also installs the
tail-end and all downstream nodes to local head-end's routing table -but
head-end will keep these to itself as a secret not advertising to anyone
else allowing for more deterministic routing in the MPLS network.
If head-end is a PE (edge-node) then autoroute-announce makes perfect sense.
However if head-end is some P-Core node then forwarding-adjacency might be
considered if you need to attract traffic to the core node hosting the
tunnel that is meant as a short-cut.  


> 3.The term signaled-bandwidth in TE,is that a limit for the traffic
carried by a
> tunnel? or is it just a reserved bandwidth for rsvp along the path of that
> tunnel?
>
It is just reserved BW for the RSVP signalled LSP.  
My advice,
Use RSVP-TE for traffic-engineering -i.e. steering traffic across the core
and not for QOS (RSVP-TE "QOS" aka Int-Serv is crazy complex).
Use standard simple QOS aka Diff-Serv to enforce quality of service in the
core.   

adam