Sdp Encapsulation Types - Alcatel-Lucent 7750 SR OS Service Manual

SDP Encapsulation Types

The Alcatel-Lucent service model uses encapsulation tunnels through the core to interconnect SR-
Series service edge routers. An SDP is a logical way of referencing the entrance to an
encapsulation tunnel.
The following encapsulation types are supported:
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GRE
GRE encapsulated tunnels have very low overhead and are best used for Best-Effort class of
service. Packets within the GRE tunnel follow the IGP (Interior Gateway Protocol) shortest path
from edge to edge. If a failure occurs within the service core network, the tunnel will only
converge as fast as the IGP itself. If ECMP (Equal Cost Multi-Path) routing is used in the core,
many loss-of-service failures can be minimized to sub-second timeframes.
MPLS
Multi-Protocol Label Switching (MPLS) encapsulation has the following characteristics:
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7750 SR OS Services Guide
L2 within Generic Routing Encapsulation (GRE)
L2 within RSVP signaled, loose hop non-reserved MPLS LSP
L2 within RSVP signaled, strict hop non-reserved MPLS LSP
L2 within RSVP-TE signaled, bandwidth reserved MPLS LSP
L2 with LDP signaled
LSPs (label switched paths) are used through the network, for example, primary,
secondary, loose hop, etc. These paths define how traffic traverses the network from point
A to B. If a path is down, depending on the configuration parameters, another path is
substituted.
Paths can be manually defined or a constraint-based routing protocol (e.g., OSPF-TE or
CSPF) can be used to determine the best path with specific constraints.
An MPLS SR-Series router supports both signaled and non-signaled LSPs through the
network.
Non-signaled paths are defined at each hop through the network.
Signaled paths are communicated via protocol from end to end using Resource
ReserVation Protocol (RSVP).
Because services are carried in encapsulation tunnels and an SDP is an entrance to the
tunnel, an SDP has an implicit Maximum Transmission Unit (MTU) value. The MTU for
Services
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