Cisco Catalyst 4500 Series Software Configuration Guide

19-3
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 19 Configuring Layer 2 Ethernet Interfaces
About Layer 2 Ethernet Switching
VLAN Trunks
A trunk is a point-to-point link between one or more Ethernet switch interfaces and another networking
device such as a router or a switch. Trunks carry the traffic of multiple VLANs over a single link and
allow you to extend VLANs across an entire network.
Only 802.1Q trunking encapsulations is available on all Catalyst 4500 Ethernet interfaces.
Note Ports 3 to 18 are blocking Gigabit ports on the WS-X4418-GB module. Ports 1 to 12 are blocking
Gigabit ports on the WS-X4412-2GB-T module.
You can configure a trunk on a single Ethernet interface or on an EtherChannel bundle. For more
information about EtherChannel, see Chapter 27, “Configuring EtherChannel and Link State Tracking.”
Layer 2 Interface Modes
Table 19-1 lists the Layer 2 interface modes and describes how they function on Ethernet interfaces.
Note DTP is a point-to-point protocol. However, some internetworking devices might forward DTP frames
improperly. To avoid this problem, ensure that interfaces connected to devices that do not support DTP
are configured with the access keyword if you do not intend to trunk across those links. To enable
trunking to a device that does not support DTP, use the nonegotiate keyword to cause the interface to
become a trunk without generating DTP frames.
Table 19-1 Layer 2 Interface Modes
Mode Purpose
switchport mode access Puts the interface into permanent nontrunking mode and
negotiates to convert the link into a nontrunking link. The
interface becomes a nontrunk interface even if the neighboring
interface does not change.
switchport mode
dynamic desirable
Makes the interface actively attempt to convert the link to a
trunking link. The interface becomes a trunk interface if the
neighboring interface is set to trunk, desirable, or auto mode.
switchport mode dynamic auto Makes the interface convert the link to a trunking link if the
neighboring interface is set to trunk or desirable mode. It is the
default mode for all Ethernet interfaces.
switchport mode trunk Puts the interface into permanent trunking mode and negotiates to
convert the link into a trunking link. The interface becomes a
trunk interface even if the neighboring interface does not change.
switchport nonegotiate Puts the interface into permanent trunking mode but prevents the
interface from generating DTP frames. You must configure the
neighboring interface manually as a trunk interface to establish a
trunking link.

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E