You are asked to implement an LDP-signaled VPLS network for a new customer. Which two
statements are correct regarding this implementation? (Choose two.)
A full mesh of LDP sessions between PEs must be configured.
The PE routers distribute VPLS to label mapping using MP-IBGP.
The same NLRI as Layer 2 VPNs is used.
The PE router advertises a label for each remote PE configured.
2 Comments on “Which two statements are correct regarding this implementation?”
A and D seem to be correct
Scaling Characteristics of LDP VPLS and BGP VPLS
There are two distinct VPLS control planes: LDP based and BGP based
To enable VPLS, all PE routers connected to common VPLS customers must be able to exchange VPLS signaling information amongst themselves.
As the number of PE routers in the network increases, scaling this signaling component of the VPLS control plane becomes essential.
For LDP-VPLS signaling, the exchange of VPLS signaling information is accomplished by setting up a full mesh of targeted LDP sessions between each pair of PE routers that have at least one VPLS in common. As the size of the VPLS network grows, the number of LDP targeted sessions increases exponentially on the order of O(N^2), where N is the number of LDP-VPLS PE routers in the network.
How Labels are Used in Label Blocks
Each PE router creates a mapping of the labels in the label block to the sites in a VPLS domain. A PE router advertising a label block with a block offset indicates which sites can use the labels to reach it. When a PE router is ready to advertise its membership to a VPLS domain, it allocates a label block and advertises the VPLS NLRI.
In this way, other PE routers in the same VPLS domain can learn of the existence of the VPLS and set up pseudowires to it if needed. The VPLS NLRI
advertised for this purpose is referred to as the default VPLS NLRI. The label block in the default VPLS NLRI is referred to as the default label block