Mpls-Te Forwarding Adjacency Restrictions; Mpls-Te Forwarding Adjacency Prerequisites; Unequal Load Balancing - Cisco CRS Configuration Manual

Unequal Load Balancing

Related Topics
Configuring MPLS-TE Forwarding Adjacency, on page 277
Configure Forwarding Adjacency: Example, on page 349

MPLS-TE Forwarding Adjacency Restrictions

The MPLS-TE Forwarding Adjacency feature has these restrictions:
• Using the MPLS-TE Forwarding Adjacency increases the size of the IGP database by advertising a TE
• The MPLS-TE Forwarding Adjacency is supported by Intermediate System-to-Intermediate System
• When the MPLS-TE Forwarding Adjacency is enabled on a TE tunnel, the link is advertised in the IGP
• MPLS-TE forwarding adjacency tunnels must be configured bidirectionally.
• Multicast intact is not supported with MPLS-TE Forwarding Adjacency.

MPLS-TE Forwarding Adjacency Prerequisites

Your network must support the following features before enabling the MPLS -TE Forwarding Adjacency
feature:
• MPLS
• IP Cisco Express Forwarding
• Intermediate System-to-Intermediate System (IS-IS)
Unequal Load Balancing
Unequal load balancing permits the routing of unequal proportions of traffic through tunnels to a common
destination. Load shares on tunnels to the same destination are determined by TE from the tunnel configuration
and passed through the MPLS Label Switching Database (LSD) to the Forwarding Information Base (FIB).
Load share values are renormalized by the FIB using values suitable for use by the forwarding code. The
Note
exact traffic ratios observed may not, therefore, exactly mirror the configured traffic ratios. This effect is
more pronounced if there are many parallel tunnels to a destination, or if the load shares assigned to those
tunnels are very different. The exact renormalization algorithm used is platform-dependent.
There are two ways to configure load balancing:
Explicit configuration
Cisco IOS XR MPLS Configuration Guide for the Cisco CRS Router, Release 5.1.x
184
tunnel as a link.
(IS-IS).
network as a Type-Length-Value (TLV) 22 without any TE sub-TLV.
Using this method, load shares are explicitly configured on each tunnel.
Implementing MPLS Traffic Engineering