(Optional) Configuring TE Attributes for a Link

TE attributes, such as the link bandwidth, administrative group, shared risk link group (SRLG), and affinity, can be configured to select a link for a CR-LSP.

Context

The TE link attributes are as follows:

Link bandwidth

This attribute is required to limit the CR-LSP bandwidth.

If no bandwidth is set for a link, the CR-LSP bandwidth may exceed the maximum reservable link bandwidth. If this happens, the CR-LSP cannot be established.
Link's TE metric

You can use the IGP metric or configure a TE metric for a link for the path calculation of a TE tunnel. If a TE metric is configured, the TE tunnel path computation is independent of the IGP, making path control of the TE tunnel more flexible.
Administrative group and affinity

An affinity determines attributes for links to be used by an MPLS TE tunnel. The affinity and the link administrative group attribute together are used to determine which links a tunnel uses.
An affinity can be set using either a hexadecimal number or a name.
- Hexadecimal number: This is traditionally used to configure the NetEngine 8000 F. A 32-bit hexadecimal number is set for each affinity and link administrative group attribute, making planning and computation complex.
- Name: This is a new mode supported by the NetEngine 8000 F. Each bit of the 128-bit administrative group and affinity attribute can be named, which simplifies configuration and maintenance. This mode is recommended.
SRLG

A shared risk link group (SRLG) is a set of links that share a physical resource (for example, an optical fiber). In an SRLG, if one link fails, the other links in the SRLG also fail.

An SRLG enhances CR-LSP reliability on an MPLS TE network with CR-LSP hot standby or TE FRR enabled. Two or more links share the same risk if they share a physical resource. For example, sub-interfaces share the same risks as their interface when links on an interface and its sub-interfaces are in an SRLG. If the interface goes down, so do its sub-interfaces. Similarly, if the links of a primary and a backup tunnel are in the same SRLG, the links of the backup tunnel share the same risks as those of the primary tunnel; so if the primary tunnel goes down, so does the backup tunnel.

Procedure

Configure the link bandwidth.
The bandwidth is set on outbound interfaces along the links of a TE tunnel that requires sufficient bandwidth.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The view of the interface on which the MPLS TE tunnel is established is displayed.
3. Run mpls te bandwidth max-reservable-bandwidth max-bw-value
  The maximum reservable link bandwidth is set.
4. Run mpls te bandwidth bc0 bc0-bw-value
  The BC bandwidth is set for the link.
  - The maximum reservable link bandwidth must not exceed the physical link bandwidth. A maximum of 80% of the link bandwidth is recommended for the maximum reservable link bandwidth.
  - The BC0 bandwidth must not exceed the maximum reservable link bandwidth.
5. Run commit
  The configuration is committed.
Set the TE metric for a link.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The view of the interface on which the MPLS TE tunnel is established is displayed.
3. Run mpls te metric metric-value
  The TE metric is set for a link.
4. Run commit
  The configuration is committed.
Configure an affinity and a link administrative group attribute in hexadecimal format.
- The modified administrative group takes effect only on subsequently established LSPs, not on LSPs that have already been established.
- The modified affinity takes effect on already established LSPs of a tunnel because the system will recalculate a path for the tunnel.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The view of the interface on which the MPLS TE tunnel is established is displayed.
3. Run mpls te link administrative group group-value
  An administrative group is configured for the link.
4. Run quit
  Return to the system view.
5. Run interface tunnel tunnel-number
  The view of the MPLS TE tunnel interface is displayed.
6. Run mpls te affinity property properties [ mask mask-value ] [ secondary | best-effort ]
  An affinity is set for the MPLS TE tunnel.
7. Run commit
  The configuration is committed.
Name hexadecimal bits of an affinity and a link administrative group attribute.
- The modified administrative group takes effect only on subsequently established LSPs, not on LSPs that have already been established.
- The modified affinity takes effect on already established LSPs of a tunnel because the system will recalculate a path for the tunnel.
1. Run system-view
  The system view is displayed.
2. Run path-constraint affinity-mapping
  An affinity name template is configured, and the template view is displayed.
  
  This template must be configured on each node that is used to calculate an MPLS TE tunnel path, and the mappings between affinity names and bits on each node must be consistent globally.
3. Run attribute bit-name bit-sequence bit-number
  A mapping between an affinity bit and name is configured.
  
  The affinity attribute contains 128 bits. You can run this command repeatedly to configure all or only some bits.
4. Run interface interface-type interface-number
  The view of the interface on which the MPLS TE tunnel is established is displayed.
5. Run mpls te link administrative group name { bit-name } &<1-32>
  An administrative group attribute is specified for the link.
  
  The bit-name value must be in the range specified in the affinity name template.
6. Run quit
  Return to the system view.
7. Run interface tunnel tunnel-number
  The view of the MPLS TE tunnel interface is displayed.
8. Run mpls te affinity { primary | secondary | best-effort } { include-all | include-any | exclude } bit-name &<1-32>
  An affinity is set for the MPLS TE tunnel.
9. Run commit
  The configuration is committed.
Configure an SRLG.

On the ingress of a hot-standby CR-LSP or a TE FRR tunnel, perform Steps 1 to 3. On the interface of each SRLG member, perform Step 5 and Step 6.
1. Run system-view
  The system view is displayed.
2. Run mpls
  The MPLS view is displayed.
3. Run mpls te srlg path-calculation [ preferred | strict ]
  An SRLG path calculation mode is configured.
  - If strict is configured, CSPF uses an SRLG as a constraint when calculating a path for a bypass or backup CR-LSP.
  - If preferred is configured, CSPF uses an SRLG as a constraint when calculating a path for a bypass or backup CR-LSP for the first time; if calculation fails, CSPF no longer uses the SRLG as a constraint.
4. Run quit
  Return to the system view.
5. Run interface interface-type interface-number
  The view of the interface on which the MPLS TE tunnel is established is displayed.
6. Run mpls te srlg srlg-number
  The interface is added to an SRLG.
  
  On a network with hot standby or TE FRR, the SRLG attribute needs to be configured for the outbound interface of the ingress on a tunnel and other members of the SRLG. A link joins an SRLG after the SRLG attribute is configured on any outbound interface of the link.
  
  To delete the SRLG attribute from all interfaces on a device, run the undo mpls te srlg all-config command in the MPLS view.
7. Run commit
  The configuration is committed.