LDP Commands

‎06-04-2019 05:56 AM

Hi All,

during my studies about LDP as Signaling Protocol i found the below:



set routing-instances MPLS-VPLS-VLAN20 protocols vpls neighbor
set protocols ldp session authentication-key "abcdef"


The first one should be

"Specify each of the PE routers participating in the VPLS domain. Configuring this statement enables LDP for signaling VPLS."


The second one is for:

"Configure LDP session parameters by specifying the session destination address."


As far as I understood the first one is needed for enabling LDP, so is a must to have command 

The second command is only in case we want to use authentication between the LDP peers.

Could you please someone confirm?

More, analising the network, I have only 2 PE devices and MPLS/LDP is active between them.

Is there any way to distinguish, in the configuration, which signaling protocol is used to establish the transport tunnel(outer label)

and which signaling protcol is instead used for the inner label? (In this case the "service" which use the mpls is vpls).

As far as i understood so far, from my studies, the typical situation is

PE1 <-> P <-> PE1


In this case are needed 2 LDP session between 

PE1 <->P


P <-> PE2

for creating the transport protocol


and LDP session (targeted LDP session i guess) beetwen

PE1 <->PE2 

for exchange the "inner" label.

In my case the topolgy is simple

PE1 <-> PE2 and is confusing me on how can i distinguish the 2 case above mentioned.


Thanks all!!


Re: LDP Commands

‎06-04-2019 07:09 AM



***set routing-instances MPLS-VPLS-VLAN20 protocols vpls neighbor 

this command is mandatory for enabling LDP to signal VPLS as opposed to BGP-signaled VPLS , check difference between draft kompella and martini , but not mandatory to enable LDP on router as basically all you need is 

  1. set protocols ldp interface <interface-name>
  2. set interface <interface-name> family mpls




and you will be able to enable LDP.


***set protocols ldp session authentication-key "abcdef"


this command "set protocols ldp session" is used for creating targeted LDP sessions and this is created between remote peers and it is needed for VPLS , command itself has some options for the session like authentication and those options are not mandatory

"Is there any way to distinguish, in the configuration, which signaling protocol is used to establish the transport tunnel(outer label)"
you can refer to the following link for configuration of BGP based VPLS and LDP based VPLS


for inner label signalling it depends on the service you are configuring L3VPN , L2circuits , VPLS , .. etc