RSVP-TE: Resource
Reservation Protocol - Traffic Extension
The RSVP-TE protocol is
an addition to the RSVP protocol for establishing label switched paths (LSPs)
in MPLSnetworks. The extended RSVP protocol (RSVP-TE) supports the
instantiation of explicitly routed LSPs, with or without resource reservations.
RSVP-TE also supports smooth rerouting of LSPs, preemption, and loop detection.
RSVP-TE defines a
session as a data flow with a particular destination and transport-layer
protocol. When RSVP and MPLS are combined, a flow or session can be defined
with greater flexibility and generality. The ingress node of an LSP (Label
Switched Path) uses a number of methods to determine which packets are assigned
a particular label. Once a label is assigned to a set of packets, the label
effectively defines the flow through the LSP. Such an LSP is an LSP tunnel
because the traffic through it is opaque to intermediate nodes along the label
switched path. New RSVP Session, Sender and Filter Spec objects, called LSP
Tunnel IPv4 and LSP Tunnel IPv6 have been defined to support the LSP tunnel
feature.
In some applications it
is useful to associate sets of LSP tunnels, such as during reroute operations
or in spreading a traffic trunk over multiple paths, which sets are called
traffic engineered tunnels (TE tunnels). To enable the identification and
association of the LSP tunnels, two identifiers are carried. A tunnel ID is
part of the Session object. The Session object uniquely defines a traffic
engineered tunnel. The Sender and Filter Spec objects carry an LSP ID. The
Sender (or Filter Spec) object, together with the Session object, uniquely
identify an LSP tunnel.
Protocol Structure - RSVP-TE Resource Reservation Protocol - Traffic
Extension Apart from the existing message types listed in RSVPan additional message
type is available:
Value
|
Message type
|
14
|
Hello
|
In addition, the following additional Protocol Object Types exist:
Value
|
Object type
|
16
|
Label
|
19
|
Optical
|
20
|
Explicit Route
|
21
|
Record Route
|
22
|
Hello
|
207
|
Attribute Session
|
