Technical Documentation

Configuring CoS Forwarding Policy (NSM Procedure)

Class-of-service (CoS)-based forwarding (CBF) enables you to control next-hop selection based on a packet’s class of service and, in particular, the value of the IP packet’s precedence bits.

You can specify a particular interface or next hop to carry high-priority traffic while all best-effort traffic takes some other path. When a routing protocol discovers equal-cost paths, it can pick a path at random or load-balance across the paths through either hash selection or round robin. CBF allows path selection based on class.

To configure CoS forwarding policy in NSM:

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the configuration tree, expand Class of Service.
  4. Select Forwarding Policy.
  5. Add or modify forwarding policy settings as specified in Table 1.
  6. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 1: Forwarding Policy Configuration Details

Task Your Action

Specify the name of forwarding class and override the incoming packet classification.

  1. Click Add new entry next to Class.
  2. In the Name box, enter the name of forwarding class.
  3. Click Classification Override next to Class.
  4. In the Forwarding Class box, enter the name of the forwarding class.

Specify the map for CoS forwarding routes.

  1. Click Add new entry next to Next Hop Map.
  2. In the Name box, enter the map that defines next-hop routes.
  3. Click Forwarding Class next to next-hop-map.
  4. Click Add new entry next to Forwarding Class.
  5. In the Name box, enter the name of the forwarding class.
  6. Select the Non LSP Next Hop check box to use a non-LSP next hop for traffic sent to the forwarding class next-hop map of the forwarding policy.
  7. Select the Discard check box to discard the traffic sent to the forwarding class for the next-hop map referenced by the forwarding policy.
  8. Click Lsp Next Hop next to forwarding-class.
  9. Click New button next to Lsp Next Hop.
  10. In the New Lsp-next-hop dialog box, enter the LSP regular expression to which to map the forwarded traffic.
  11. Click Next Hop next to forwarding-class.
  12. In the New next-hop dialog box, enter the next-hop name or address to which to map forwarded traffic.

Published: 2009-08-23