Revision as of 14:59, 7 September 2010

Describing Routing Between VLANs

Inter-VLAN Routing Using an External Router

Inter VLAN Routing

Configuration

Configuring Inter-VLAN Routing Using an External Router

802.1Q Trunk configuration

802.1Q Trunk configuration

Explaining Multilayer Switching

Multilayer Switching

L3 Switching packet flow

Frame Rewrite

Packet rewrite

Content Addressable Memory

Ternary Content Addressable Memory

Describing Configuration Commands for Inter-VLAN Communication on a Multilayer Switch

Multilayer configuration

Describing Routed Ports on a Multilayer Switch

Routed switchport

Routed switchport configuration

Deploying CEF-Based Multilayer Switching

Explaining Layer 3 Switch Processing

Switch Processing

There is a wide range of CEF-based Cisco multilayer switches:

• Catalyst 2970
• Catalyst 3550
• Catalyst 3560
• Catalyst 3750
• Catalyst 4500
• Catalyst 4948
• Catalyst 6500

Identifying the Multilayer Switch Packet Forwarding Process

MLS lookup

ARP Throttling

MPLS operation

• Null adjacency: Packets destined for a null0 interface are dropped. This can be used as an effective form of access filtering.
• Glean adjacency: When a router is connected directly to several hosts, the FIB table on the router maintains a prefix for the subnet rather than for the individual host prefixes. The subnet prefix points to a glean adjacency. When packets need to be forwarded to a specific host, the adjacency database is gleaned for the specific prefix.
• Punt adjacency: Features that require special handling, or features that are not yet supported in conjunction with CEF switching paths, are forwarded to the next switching layer for handling. For example, the packet may require CPU processing. Features that are not supported are forwarded to the next-higher switching level.
• Discard adjacency: Packets are discarded.
• Drop adjacency: Packets are dropped, but the prefix is checked.

Describing CEF Configuration Commands

Configure CEF

Switching Methods

Summary

Chapter Summary