Branch router —A router that has more than one directly connected downstream routers. A router where packet replication occurs.
Bud router —An egress router that has one or more directly connected downstream routers. A bud node can be a branch node and a destination.
Crossover —A condition that occurs at an intersecting node when two or more incoming sub-LSPs that belong to the same LSP have different input interfaces and different output interfaces.
Egress router —One of potentially many destinations of the P2MP TE sub-LSP. Egress routers may also be referred to as tailend routers, leaf nodes, or leaves.
Data duplication —A condition that occurs when an egress router receives duplicate packets. The condition can happen as a result of re-optimization of LSPs, remerge, or crossover. It causes network bandwidth to be wasted and should be minimized.
Grafting —The process of adding a new sub-LSP to a P2MP TE tunnel.
Headend router —An ingress PE router that is at the “headend” of a P2MP tunnel.
Ingress router —The router that initiates the signaling messages that set up the P2MP TE LSP. Also known as the headend router.
MDT —A Multicast Domain/Distribution tree in the core that carries traffic and/or control messages for a given VPN. An MDT implicitly implies that we are discussing the Domain-Model. And MDT can have multiple types of encapsulation in the core, for example, GRE, IP-in-IP or MPLS.
MFI —MPLS forwarding infrastructure.
mLDP —Multicast signaling extensions to LDP
P2MP ID (P2ID) —A unique identifier of a P2MP TE LSP, which is constant for the whole LSP regardless of the number of branches and/or leaves.
P2MP LSP —One or more source to leaf sub-LSPs. It is identified by 5-tuple key:
Session
-
P2MP ID
-
Tunnel ID
-
Extended Tunnel ID
Sender Template
-
Tunnel sender address
-
LSP ID
P2MP Sub-LSP —A segment of a P2MP TE LSP that runs from the headend router to one destination. A sub-LSP is identified by the following 7-tuple key:
P2MP session
-
P2MP ID
-
Tunnel ID
-
Extended tunnel ID
Sender template
-
Tunnel sender address
-
LSP ID
-
Subgroup ID originator
-
Subgroup ID
P2MP-TE —point to multipoint traffic engineering
P2MP tree —The ordered set of routers and TE links that comprise the paths of P2MP TE sub-LSPs from the ingress router to all of the egress routers.
P2MP tunnel —A group of one of more P2MP LSPs. A tunnel has the following 3-tuple key:
-
P2MP ID
-
Tunnel ID
-
Extended tunnel ID.
PIM —Protocol Independent Multicast
PIM-SM —PIM Sparse Mode, see RFC 4601
PIM-SSM —PIM Source Specific Multicast, a subset of PIM-SM. See RFC 4601.
Pruning —The process of removing a sub-LSP from a a P2MP LSP.
Receiver —A recipient of traffic carried on a P2MP service supported by a P2MP sub-LSP. A receiver is not necessarily an egress router of the P2MP LSP. Zero, one, or more receivers may receive data through a given egress router.
Remerge —A condition that occurs at an intersecting node when two data streams belonging to the same P2MP LSP merge into onto one data stream as they exit the intersecting node.
Sibling LSP —Two LSPs that belong to the same P2MP tunnel, meaning that the session objects are the same for both LSPs.
Sibling sub-LSP —Two sub-LSPs that belong to the same P2MP LSP, meaning that the session and sender template objects are the same for both sub-LSPs.
Source —The sender of traffic that is carried on a P2MP service supported by a P2MP LSP. The sender is not necessarily the ingress router of the P2MP LSP.
Tailend router —An egress PE router that is at the “tailend” of a P2MP tunnel.