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MPLS and RSVP-TE
3.4.1.6
LSPs can be signaled with explicit reservation styles for the reservation of resources,
such as bandwidth. A reservation style describes a set of attributes for a reservation,
including the sharing attributes and sender selection attributes. The style information
is part of the LSP configuration. The 7705 SAR supports two reservation styles:
If the FRR option is enabled for the LSP and the facility FRR method is selected at
the head-end node, only the SE reservation style is allowed. If a 7705 SAR PLR node
receives a PATH message with fast reroute requested with facility method and the
FF reservation style, it will reject the reservation. The one-to-one backup method
supports both FF and SE styles.
3.4.1.7
The implicit null label option enables an eLER to receive MPLS packets from the
previous-hop LSR without the outer LSP label.
The implicit null label is included in RESV messages sent by the eLER to the
previous-hop LSR. When the implicit null label is signaled to the LSR, it pops the
outer label before sending the MPLS packet to the eLER; this is known as
penultimate hop popping.
The implicit null label option can be enabled for all RSVP-TE interfaces and for all
RSVP-TE LSPs for which the router is the eLER by using the implicit-null-label
command in the config>router>rsvp context.
RSVP-TE must be shut down before this command can be used.
52
RSVP-TE Reservation Styles
• fixed filter (FF) — the fixed filter (FF) reservation style specifies an explicit list of
senders and a distinct reservation for each of them. Each sender has a
dedicated reservation that is not shared with other senders. Each sender is
identified by an IP address and a local identification number, the LSP ID.
Because each sender has its own reservation, a unique label and a separate
LSP can be constructed for each sender-receiver pair. For traditional RSVP
applications, the FF reservation style is ideal for a video distribution application
in which each channel (or source) requires a separate pipe for each of the
individual video streams.
• shared explicit (SE) — the shared explicit (SE) reservation style creates a single
reservation over a link that is shared by an explicit list of senders. Because each
sender is explicitly listed in the RESV message, different labels can be assigned
to different sender-receiver pairs, thereby creating separate LSPs.
Implicit Null Label
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MPLS Guide
3HE 18686 AAAB TQZZA
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