MPLS LDP filtering

[daniel-nilsson]

Hi
What is the difference between these to?
MPLS LDP - Local Label Allocation Filtering
MPLS LDP - Inbound Label Binding Filtering

Thanks
/Daniel

[Victor Acevedo]

Hey Daniel,

Local Label Allocation Filter refers to how we will allocate labels on this particular device. For example if we have a device, PE1, by default this device will allocate a label for each prefix received from an IGP. We can change that so this device only allocates a label for let's say, /32 Loopback IP addresses. Hence, it reduces the amount of labels we allocate and advertise to our LDP peers.

This filtering can be accomplished via:

enable
configure terminal
mpls ldp label
allocate global prefix-list {list-name | list-number}

Local Label Allocation Filtering

Inbound Label Binding Filtering

With Inbound binding filtering, we are filtering on the label bindings being advertised from our MPLS LDP peers. Let's say we have PE1 which is connected to P1 router. P1 router is getting a lot of unnecessary label bindings and is advertising all of them to PE1. What we can do on PE1 is configure an ACL to only accept certain prefix label bindings from this peer or from any peer. 

configure terminal
access-list 1 permit 10.63.0.0 0.63.255.255 
mpls ldp neighbor 10.110.0.10 labels accept 1 

Inbound Label Filtering

Thx,

Victor Hugo Acevedo

[daniel-nilsson]

So i can use either of them to allocate only PE loopbacks for MPLS VPN?

[Victor Acevedo]

Hey Daniel,

You can use "Local Label Allocation Filtering" to only generate labels for your loopback and/or configure "Inbound Label Binding Filtering" to only accept Label bindings for your other PE's loopback addresses. So either option will accomplish what you are looking for, the key difference being with the 2nd option, you will also advertise all other label bindings but will ultimately be dropped at our peers. 

Thx,

Victor Hugo Acevedo