Supported Hardware Features - Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual

MPLS Label Switching
For a native IP packet (when the penultimate router has popped the label), the PFC3B performs a route
lookup in the FIB TCAM.
For a MPLS VPN packet, after the Interior Gateway Protocol (IGP) label is popped at penultimate router,
the VPN label remains. The operation that the PFC3B performs depends on the VPN label type. Packets
carrying aggregate labels require a second lookup based on the IP header after popping the aggregate label.
For a nonaggregate label, the PFC3B performs a route lookup in the FIB TCAM to obtain the IP next
hop information.
For the case of a packet with an IGP label and a VPN label, when there is no penultimate hop popping
(PHP), the packet carries the explicit-null label on top of the VPN label. The PFC3B looks up the top
label in the FIB TCAM and recirculates the packet. Then the PFC3B handles the remaining label as
described in the preceding paragraph, depending on whether it is an aggregate or nonaggregate label.
Packets with the explicit-null label for the cases of EoMPLS, MPLS, and MPLS VPN an MPLS are
handled the same way.
MPLS VPN Forwarding
There are two types of VPN labels: aggregate labels for directly connected network or aggregate routes,
and nonaggregate labels. Packets carrying aggregate labels require a second lookup based on the IP
header after popping the aggregate label. The VPN information (VPN-IPv4 address, extended
community, and label) is distributed through the Multiprotocol-Border Gateway Protocol (MP-BGP).
Recirculation
In certain cases, the PFC3B provides the capability to recirculate the packets. Recirculation can be used
to perform additional lookups in the ACL or QoS TCAMs, the Netflow table, or the FIB TCAM table.
Recirculation is necessary in these situations:
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Packet recirculation occurs only on a particular packet flow; other packet flows are not affected.The
rewrite of the packet occurs on the modules; the packets are then forwarded back to the PFC3B for
additional processing.

Supported Hardware Features

The following hardware features are supported:
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Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
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To push more than three labels on imposition
To pop more than two labels on disposition
To pop an explicit null top label
When the VPN Routing and Forwarding (VRF) number is more than 511
For IP ACL on the egress interface (for nonaggregate (per-prefix) labels only)
Label operation— Any number of labels can be pushed or popped, although for best results, up to
three labels can be pushed, and up to two labels can be popped in the same operation.
IP to MPLS path—IP packets can be received and sent to the MPLS path.
MPLS to IP path—Labeled packets can be received and sent to the IP path.
MPLS to MPLS path—Labeled packets can be received and sent to the label path.
MPLS Traffic Engineering (MPLS TE)—Enables an MPLS backbone to replicate and expand the
traffic engineering capabilities of Layer 2 ATM and Frame Relay networks.
Chapter 21 Configuring Multiprotocol Label Switching
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