Routing
Routing

MPLS explicit-null

10.12.17   |  
a week ago

Hi Team,

 

What is the benifit of configuring the explicit-null under protocols/mpls at the EDGE level (LER) ?

In other term, what is the use case of configuring it at LER level ?

 

BR/

Zakour

2 REPLIES
Routing

Re: MPLS explicit-null

10.12.17   |  
a week ago

Hi Zakor,

 

When you configure MPLS explicit-null labels, label 0 is advertised to the egress router of an LSP. When label 0 is advertised, the egress router (instead of the penultimate router) removes the label. Ultimate-hop popping ensures that any packets traversing an MPLS network include a label

 

We can say the implicit-null label is used by default and works well if the network has not particular QoS requirement, or if the QoS is end to end between the CPEs. On the other hand, the explicit-null label is used when the MPLS core network needs to know the QoS values.

 

Hope this helps

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Routing

Re: MPLS explicit-null

10.12.17   |  
a week ago

Hello,

 


mzakour wrote:

Hi Team,

 

What is the benifit of configuring the explicit-null under protocols/mpls at the EDGE level (LER) ?

 


This is "explicit-null"/EN for RSVP, LDP explicit-null/EN is configured at different stanza.

And AFAIK, since JUNOS supports "ultimate-hop-popping"/UHP in recent releases https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/mpls-ultimate-hop-poppin..., there isn't any EN benefit remaining, in my view.

You may see that EN is internally processed differently than any other label on certain platforms like PTX with FPC1/2 cards although I agree that PTX as LER is not a common use case.

HTH

Thx

Alex

 

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