Bgp Vpls; Figure 79: Bgp Vpls Solution - Alcatel-Lucent 7750 SR Manual

BGP VPLS

The Alcatel-Lucent BGP VPLS solution, compliant with RFC 4761, is described in this section.
Figure 79
components and the deltas from LDP VPLS with BGP AD are explained below:
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Figure 79: BGP VPLS Solution

depicts the service representation for BGP VPLS mesh. The major BGP VPLS
Data plane is identical with the LDP VPLS solution: for example, VPLS instances
interconnected via pseudowire mesh. Split horizon groups may be used for loop avoidance
between pseudowires.
Addressing is based on two (2) bytes VE ID assigned to the VPLS instance.
→ BGP-AD for LDP VPLS: 4 bytes VSI-ID (system IP) identifies the VPLS instance.
The target VPLS instance is identified by the Route Target (RT) contained in the MP-BGP
advertisement (extended community attribute).
→ BGP-AD: a new MP-BGP extended community is used to identify the VPLS. RT is
used for topology control.
Auto-discovery is MP-BGP based. Same AFI, SAFI used as for LDP VPLS BGP-AD.
→ The BGP VPLS updates are distinguished from the BGP-AD ones based on the value
of the NLRI prefix length: 17 bytes for BGP VPLS, 12 bytes for BGP-AD
→ BGP-AD NLRI is shorter since there is no need to carry pseudowire label information
as T-LDP does the pseudowire signaling for LDP VPLS
Pseudowire label signaling is MP-BGP based. As a result the BGP NLRI content includes
also label related information – for example, block offset, block size and label base.
→ LDP VPLS: target LDP (T-LDP) is used for signaling the pseudowire service label.
→ The L2 extended community proposed in RFC 4761 is used to signal pseudowire
characteristics – for example, VPLS status, control word, sequencing
7750 SR OS Services Guide