Advanced Configuration and Management Guide

Layer 3 Filters

Layer 3 filters control a device’s transmission and receipt of packets based on routing protocol information in the packets. The routing switches and switch provide the following types of Layer 3 filters:

•IP forwarding filters (same as IP access policies, see “IP Access Policies” on page C-7)

•IP/RIP route filters

•IP/RIP neighbor filters

•IPX forwarding filters

•IPX RIP route and neighbor filters

•IPX SAP service filters

•AppleTalk zone filters

•AppleTalk network filters

•BGP route address filters

•BGP route AS-path filters

•BGP route community filters

•IP/RIP redistribution filters

•OSPF redistribution filters

•BGP redistribution filters

IP Filters

IP filters control the IP packets that the device sends and receives and the routes that the device learns or advertises. IP forwarding filters (IP Access policies) control transmission and receipt of IP packets, while IP/RIP route and neighbor filters control the routes that the device leans or advertises. Route filters filter on specific network addresses while neighbor filters filter on the IP addresses of the IP/RIP neighbors.

IP Forwarding Filters

IP forwarding filters determine whether to forward or drop an IP packet. IP forwarding filters on a switch or routing switch are called “IP access policies”. See “IP Access Policies” on page C-7.

IP/RIP Route Filters

IP/RIP route filters control the routes that a device learns and advertises. Figure D.4 shows an example of a port with IP/RIP route filters. The port has filters for the inbound direction and the outbound direction. Notice that the same filter can be used for both directions. The inbound filters control the routes that the device learns; denied routes are not learned by the device. Outbound filters control the routes that the device advertises; denied routes are not advertised to RIP neighbors.

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