Pbts Forward Class - Cisco ASR 9000 Series Configuration Manual
Aggregation services router mpls
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Also See for ASR 9000 Series:
- Command reference manual (1138 pages) ,
- Routing configuration manual (702 pages) ,
- Reference manual (696 pages)
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Implementing MPLS Traffic Engineering
• Classify the IPv4 packets based on DSCP/ToS/IPP value carried in the packet, configured via ACL.
• Classify the MPLS packets based on EXP bit value carried in the packet.
• Classify the MPLS packets based on remarked EXP value (i.e., the value after taking QoS marking
action).
• Ability to associate the class-map with forwarding group.
• Ability to define the forward-class for TE interface. Only one forward-class can be associated with a
TE at any time. The forward-class provides ability to map multiple/any EXP or multiple classes of
packets to the same forward-class.
• Support for default forward-class (0). If the TE interface is not explicitly associated with a forward-class,
it is by default associated with default forward-class (0).
• PBTS is turned on the ingress interface by applying the service-policy at the targeted input interface(s).
• PBTS can be enabled on any of the L3 interfaces—physical, sub-interface, and bundle interface.
• PBTS allows in-place modification of the configuration (both class-map and forward-group to TE
association).
Related Topics
Configuring Policy-based Tunnel Selection, on page 198
PBTS Forward Class
In PBTS, a class-map is defined for various types of packet, and associating this class-map with a forward-class.
The class-map defines the matching criteria for classifying a particular type of traffic, while the forward-class
defines the forwarding path these packets should take. Once a class-map is associated with a forwarding-class
in the policy map, all the packets that match the class-map are forwarded as defined in the policy-map. The
egress traffic engineering (TE) tunnel interfaces that the packets should take for each forwarding-class is
specified by associating the TE interface explicitly, or implicitly in the case of default value, with the
forward-group. When the TE interfaces are associated with the forward-class, they can be exported to the
routing protocol module using the auto-route command, which will then associate the route in the FIB database
with these tunnels. If the TE interface is not explicitly associated with a forward-class, it gets associated with
a default-class (0). All non-TE interfaces through the destination route was learned will be pushed down by
routing protocol to the forwarding plane with forwarding class set to default-class.
When PBR is configured, TE tunnel interfaces are selected to forward traffic based on matching class-types
in policy-class. When a forward-class value for a TE tunnel is configured, that TE process pass to LSD process
as part of the label rewrite for the tunnel head. The TE allows one 32-bit value for a forward-class per tunnel
that is opaque to TE and TE will use it to program the tunnel in forwarding.
PBTS supports a maximum of eight forward-class and eight TE tunnels with in each forward-class. A maximum
of 32 TE tunnels can be associated with the destination route.
Forward-class configuration is supported for auto-mesh tunnels and forward-class can be configured in the
attribute-set used by the auto-mesh tunnels. Changing the forward-class configuration does not affect the
tunnel state. TE updates the forwarding with the new forward-class value. For TE path protection, both primary
and standby LSPs use the same forward-class value for the tunnel. Unequal load-sharing of traffic is supported
for the ECMP TE tunnels across forward-classes.
Forward-class configuration does not apply to the FRR backup tunnels and will be ignored. The forward-class
configuration is not supported for the auto-backup tunnels and P2MP-TE (MTE) tunnels.
OL-28381-02
Cisco ASR 9000 Series Aggregation Services Router MPLS Configuration Guide, Release 4.3.x
Policy-Based Tunnel Selection
133
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