Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 784)

760 Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide
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How BGP-based auto-discovery for VPLS works
8
Terms introduced in this chapter
BGP-based auto-discovery for VPLS – Also called VPLS auto-discovery, this feature enables
automatic discovery of VPLS Provider Edge (PE) devices that are part of the same VPLS domain,
and the ability to detect and converge when other PE routers are added to or removed from the
VPLS domain.
BGP L2VPN VPLS Routing Information Base (RIB) – Also called the BGP L2VPN RIB, this is the
database that contains information about VPLS endpoints that are automatically discovered
through VPLS auto-discovery.
L2VPN VPLS address family or L2VPN address family – This is the BGP-based auto-discovery
mechanism used to distribute information about VPLS endpoints. Information is stored in the BGP
L2VPN VPLS Routing Information Base.
Label Switch Router (LSR) ID – This is the router ID. LDP assigns the default loopback address as
the router ID. Because VPLS auto-discovery uses the services of LDP, a valid loopback address
must be configured on the Brocade device before VPLS auto-discovery can be enabled.
Route Distinguisher (RD) – The address qualifier used within a single Internet Service Provider's
(ISP’s) Multi-Protocol Label Switching (MPLS) network. The qualifier is used to distinguish the
distinct Virtual Private Network (VPN) routes of separate customers who connect to the service
provider.
Route Target (RT) Extended Community – Defines the import and export policies applied to a VPLS
instance. Each VPLS instance is associated with one or more route target extended communities.
Subsequent Address Family Identifier (SAFI) – An ID number that provides additional information
about the NLRI type for a given attribute.
VPLS Virtual Circuit Identifier (VPLS VCID) or VPLS ID – Identifies the endpoints of a VPLS instance.
All Provider Edge (PE) routers that are part of the same VPLS instance have the same VPLS VCID.
How BGP-based auto-discovery for VPLS works
The devices use the services of LDP and BGP4 to automatically discover VPLS endpoints that are
part of the same VPLS domain. To enable the Brocade device to distribute information about VPLS
endpoints, the user must configure a L2VPN VPLS address family, activate BGP peering on the
L2VPN VPLS address family, then enable BGP-based auto-discovery for VPLS. When BGP L2VPN
VPLS update messages are exchanged between PE routers, the device can start discovering VPLS
peer addresses.
For every VPLS instance on which BGP-based auto-discovery is enabled, the device automatically
generates a Route Distinguisher (RD) value based on the BGP Autonomous System (AS) number
and the VPLS Virtual Circuit Identifier (VCID) for PE routers. The RD Is an address qualifier used by
the PE router to distinguish VPN routes of separate customers. Also, when not manually configured,
the device automatically generates import and export route targets that define the policies that
each VPLS instance uses. A local VPLS endpoint Network Layer Reachability Information (NLRI) and
import route-target tree are also created and sent to BGP peers with the L2VPN VPLS capability.
When the device receives information about a VPLS endpoint, it checks when its extended
community matches any locally-configured VPLS import route targets. When a match is found,
information about the VPLS endpoint is stored in the BGP L2VPN routing table and a notification is
sent to VPLS for peering information. Once VPLS receives the information, it creates a VPLS peer
and starts a peering session.