Cisco WS-X6K-S2-PFC2 Software Guide - Page 343

Understanding How Policy-Based Forwarding Works, Hardware and Software Requirements - ws x6k s2 msfc2

Page 343 highlights

Chapter 16 Configuring Access Control Understanding How Policy-Based Forwarding Works PBF is described in these sections: • Understanding How Policy-Based Forwarding Works, page 16-47 • Hardware and Software Requirements, page 16-47 • Configuring Policy-Based Forwarding, page 16-48 • Policy-Based Forwarding Configuration Example, page 16-55 Understanding How Policy-Based Forwarding Works PBF configuration involves these steps: • Enabling PBF and specifying a MAC address for the PFC2 • Configuring VACLs for PBF • Configuring attached hosts for PBF You enable PBF by specifying a MAC address for the PFC2. The MAC address can be a default or user-specified MAC address. Packets have to be sent with the destination MAC address equal to the PFC2 MAC address. The PFC2 must think the packet is a Layer 3 packet or no rewrite operation occurs. If packets are not sent with the PFC2 MAC address, the PFC2 treats the packets as Layer 2 packets. The PBF VACL is created using the security ACL (VACL) commands (set security acl commands). The PBF VACL contains an adjacency table entry for the PFC2 and a redirect ACE. You must set VACLs on both VLANs that participate in PBF. When the packet from the source VLAN comes into the PFC2, it hits the PBF VACL. Based on the information provided in the adjacency table, the packet header is rewritten (destination VLAN and source and destination MAC addresses) and the packet is forwarded to the destination VLAN. The packets are forwarded between VLANs only if they hit the VACL entries that are associated with the adjacency information. Note Because VACLs are applied to incoming and outgoing traffic, you must configure all VACLs carefully when using PBF. If the VACLs are not specific, a rewritten packet could hit a deny statement in the outgoing VACL and be dropped. When a router is not present in the network, you need to specify static ARP entries on participating hosts. Hardware and Software Requirements PBF hardware and software requirements are as follows: • PBF requires Supervisor Engine 2 with the Policy Feature Card 2 (PFC2) (WS-X6K-S2-PFC2). • PBF is not supported with an operating (booted) Multilayer Switch Feature Card 2 (MSFC2) in the Catalyst 6000 family switch that is being used for PBF. If you try to configure PBF with an MSFC2 present and booted, the system responds with a message indicating the feature is not supported with an MSFC2. If an MSFC2 is present but has not booted, you can configure PBF. • PBF requires supervisor engine software release 6.3(1) or later releases. 78-13315-02 Catalyst 6000 Family Software Configuration Guide-Releases 6.3 and 6.4 16-47

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16-47
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
78-13315-02
Chapter 16
Configuring Access Control
Understanding How Policy-Based Forwarding Works
PBF is described in these sections:
Understanding How Policy-Based Forwarding Works, page 16-47
Hardware and Software Requirements, page 16-47
Configuring Policy-Based Forwarding, page 16-48
Policy-Based Forwarding Configuration Example, page 16-55
Understanding How Policy-Based Forwarding Works
PBF configuration involves these steps:
Enabling PBF and specifying a MAC address for the PFC2
Configuring VACLs for PBF
Configuring attached hosts for PBF
You enable PBF by specifying a MAC address for the PFC2. The MAC address can be a default or
user-specified MAC address. Packets have to be sent with the destination MAC address equal to the PFC2
MAC address. The PFC2 must think the packet is a Layer 3 packet or no rewrite operation occurs. If packets
are not sent with the PFC2 MAC address, the PFC2 treats the packets as Layer 2 packets.
The PBF VACL is created using the security ACL (VACL) commands (
set security acl
commands). The
PBF VACL contains an adjacency table entry for the PFC2 and a redirect ACE. You must set
VACLs on
both VLANs that participate in PBF.
When the packet from the source VLAN comes into the PFC2, it hits
the PBF VACL. Based on the information provided in the adjacency table, the packet header is rewritten
(destination VLAN and source and destination MAC addresses) and the packet is forwarded to the
destination VLAN. The packets are forwarded between VLANs only if they hit the VACL entries that are
associated with the adjacency information.
Note
Because VACLs are applied to incoming and outgoing traffic, you must configure all VACLs
carefully when using PBF. I
f the VACLs are not specific, a rewritten packet could hit a deny statement
in the outgoing VACL and be dropped.
When a router is not present in the network, you need to specify static ARP entries on participating hosts.
Hardware and Software Requirements
PBF hardware and software requirements are as follows:
PBF requires Supervisor Engine 2 with the Policy Feature Card 2 (PFC2) (WS-X6K-S2-PFC2).
PBF
is not
supported with an operating (booted) Multilayer Switch Feature Card 2 (MSFC2) in the
Catalyst 6000 family switch that is being used for PBF.
If you try to configure PBF with an MSFC2 present and booted, the system responds with a message
indicating the feature is not supported with an MSFC2.
If an MSFC2 is present but has not booted, you can configure PBF.
PBF requires supervisor engine software release 6.3(1) or later releases.