Cisco Cisco IOS Software Release 12.0(23)S
MPLS Traffic Engineering (TE)—Link and Node Protection, with RSVP Hellos Support
Bandwidth Protection Considerations
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Cisco IOS Release 12.0(23)S
Bandwidth Protection Considerations
There are numerous ways in which bandwidth protection can be ensured.
describes the
advantages and disadvantages of two methods.
Cisco implementation of FRR does not mandate a particular approach, and it provides the flexibility to
use either of the above approaches. However, given a range of configuration choices, be sure that the
choices constant with a particular bandwidth protection strategy.
use either of the above approaches. However, given a range of configuration choices, be sure that the
choices constant with a particular bandwidth protection strategy.
The following sections describe some important issues in choosing an appropriate configuration:
•
•
Using Backup Tunnels with Explicitly Signaled Bandwidth
There are two bandwidth parameters that must be set for a backup tunnel:
•
actual signaled bandwidth
•
backup-bandwidth
To signal bandwidth requirements of a backup tunnel, configure the bandwidth of the backup tunnel by
using the tunnel mpls traffic-eng bandwidth command.
using the tunnel mpls traffic-eng bandwidth command.
To configure the backup-bandwidth of the backup tunnel, use the tunnel mpls traffic-eng backup-bw
command.
command.
The signaled bandwidth is used by the LSRs on the path of the backup tunnel to perform admission
control and do appropriate bandwidth accounting.
control and do appropriate bandwidth accounting.
The backup-bandwidth is used by the PLR (the head-end of the backup tunnel) to decide how much
primary traffic can be rerouted to this backup tunnel if there is a failure.
primary traffic can be rerouted to this backup tunnel if there is a failure.
Both parameters need to be set to ensure proper operation. The numerical value of the signaled
bandwidth and the backup-bandwidth should be the same.
bandwidth and the backup-bandwidth should be the same.
Protected Bandwidth Pools and the Bandwidth Pool from which the Backup Tunnel Reserves its Bandwidth
The tunnel mpls traffic-eng bandwidth command allows you to configure the following:
•
Amount of bandwidth a backup tunnel reserves
•
The DS-TE bandwidth pool from which the bandwidth needs to be reserved
Table 14
Bandwidth Protection Methods
Method
Advantages
Disadvantages
Reserve bandwidth for
backup tunnels explicitly.
backup tunnels explicitly.
It is simple.
It is a challenge to allow bandwidth
sharing of backup tunnels
protecting against independent
failures.
sharing of backup tunnels
protecting against independent
failures.
Use backup tunnels that are
signaled with zero bandwidth.
signaled with zero bandwidth.
It provides a way to share
bandwidth used for protection
against independent failures, so
it ensures more economical
bandwidth usage.
bandwidth used for protection
against independent failures, so
it ensures more economical
bandwidth usage.
It may be complicated to determine
the proper placement of zero
bandwidth tunnels.
the proper placement of zero
bandwidth tunnels.