Specifications

CHAPTER 4
InterVLAN Routing
encapsulation dot1Q 20
ip address 10.1.20.1 255.255.255.0
!
interface FastEthernet0/1.99
description Native VLAN
encapsulation dot1Q 99 native
ip address 10.1.99.1 255.255.255.0
!
interface FastEthernet0/1.120
description Data VLAN
encapsulation dot1Q 120
ip address 10.1.120.1 255.255.255.0
InterVLAN Routing Using Multilayer Switches
A multilayer switch can do both Layer 2 switching and Layer 3 routing between VLANs. This section walks you through
the switching process and focuses on order of operations. The order in which things happen is extremely important for
two reasons. First, the order of events is good test material. Second, understanding the processing order allows you to
evaluate how the various filtering and forwarding mechanisms interact. (Examples include error checking, access-lists,
VLAN access-lists, routing, and QoS.)
The Layer 2 and Layer 3 Forwarding Process
A multilayer switch does Layer 2 forwarding when the destination MAC address is mapped to one of its interfaces. The
steps involved in Layer 2 forwarding are as follows:
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CCNP SWITCH 642-813 Quick Reference by Denise Donohue
9781587140112.qxd 11/23/09 11:35 AM Page 50
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