H3C Technologies H3C SR8800 - Manual (Page 80)

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Configuring Cooperation of RSVP-TE and BFD
On an MPLS TE network, if a link between neighboring LSRs fails, the corresponding MPLS TE tunnel will
fail to forward packets. MPLS TE itself cannot detect a link failure in time. To address this issue, you can
enable Bidirectional Forwarding Detection (BFD) for RSVP-TE on the two peers of an RSVP-TE tunnel. Then,
MPLS TE can be quickly aware of link failures between the peers, ensuring that data can be switched
from the main path to the backup path.
To configure BFD for an RSVP-TE-enabled interface:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter the view of an MPLS
RSVP-TE enabled interface. interface interface-type
tunnel-number
N/A
3. Enable BFD on the RSVP-TE
enabled interface.
mpls rsvp-te bfd enable Disabled by default
Tuning CR-LSP setup
A CR-LSP is established through the signaling protocol based on the path calculated by CSPF using TEDB
and constraints. MPLS TE can affect CSPF calculation in many ways to determine the path that a CR-LSP
can traverse.
Configuration prerequisites
The configuration tasks described in this section are about CSPF of MPLS TE. They must be used in
conjunction with CSPF and the dynamic signal protocol (CR-LDP or RSVP-TE). Before performing them, be
aware of each configuration objective and its impact on your system.
Configuration procedure
Configuring the tie breaker in CSPF
CSPF only calculates the shortest path to the end of a tunnel. If multiple paths are present with the same
metric, only one of them is selected. Tie-breaking methods, in the descending order of selection priority,
include: selecting a path with the lowest bandwidth usage ratio (the used bandwidth to the maximum
reservable link bandwidth), selecting a path with the highest bandwidth usage ratio (the used bandwidth
to the maximum reserved link bandwidth), and selecting a path randomly.
To configure the CSPF tie-breaking method:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter MPLS view. mpls N/A
3. Specify the tie breaker that a
tunnel uses to select a path
when multiple paths with the
same metric are present on
the current node.
mpls te tie-breaking { least-fill |
most-fill | random }
Optional.
The random keyword applies by
default.