Understanding Cef For Pfc2 - Cisco WS-X6066-SLB-APC - Content Switching Module Software Manual

Understanding How Layer 3 Switching Works
Understanding IP Multicast Rewrite
Received IP multicast packets are (conceptually) formatted as follows:
Layer 2 Frame Header
Destination Source
1
Group G1 MAC Source A MAC
1. In this example, Destination B is a member of Group G1.
After the switch rewrites an IP multicast packet, it is (conceptually) formatted as follows:
Frame Header
Destination Source
Group G1 MAC MSFC2 MAC

Understanding CEF for PFC2

These sections describe CEF for PFC2:
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CEF for PFC2 Overview
Supervisor Engine 2, PFC2, and MSFC2 provide Layer 3 switching with CEF for PFC2. CEF for PFC2
is permanently enabled on Supervisor Engine 2. Cisco IOS CEF is permanently enabled on the MSFC2
in support of CEF for PFC2.
CEF for PFC2 works with CEF (for unicast traffic) and PIM (for multicast traffic) on the MSFC2 to
support IP, IP multicast, and IPX traffic. CEF and PIM on the MSFC2 are enhanced to support CEF for
PFC2. CEF for PFC2 generates flow statistics for Layer 3-switched traffic that can be displayed at the
CLI or used for NDE.
CEF for PFC2 provides Layer 3 switching for all packets that match a complete forwarding information
base (FIB) entry (see the
packets that match an incomplete FIB entry (one where the MAC address has not been resolved) to the
MSFC2 to be routed until the MSFC2 resolves the MAC address.
CEF for PFC2 sends bridge traffic that is addressed at Layer 2 to the MSFC2 to be processed.
Note
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
13-4
Layer 3 IP Header
Destination
Group G1 IP
IP Header
Destination
Group G1 IP
CEF for PFC2 Overview, page 13-4
Understanding Forwarding Decisions, page 13-5
Understanding the FIB, page 13-5
Understanding the Adjacency Table, page 13-6
Partially and Completely Switched Multicast Flows, page 13-7
CEF for PFC2 Examples, page 13-7
"Understanding the FIB" section on page
Source TTL
Source A IP n
Source TTL
Source A IP n–1
13-5). CEF for PFC2 sends all
Chapter 13 Configuring CEF for PFC2
Data FCS
Checksum
calculation1
Data FCS
Checksum
calculation2
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