Cisco Catalyst 4500 Series Administration Guide

18-4
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
OL_28731-01
Chapter 18 Configuring Layer 2 Ethernet Interfaces
Default Layer 2 Ethernet Interface Configuration
Default Layer 2 Ethernet Interface Configuration
Table 18-2 shows the Layer 2 Ethernet interface default configuration.
Layer 2 Interface Configuration Guidelines and Restrictions
When using (or configuring) Layer 2 interfaces, consider these guidelines and restrictions:
• In a network of Cisco switches connected through 802.1Q trunks, the switches maintain one instance
of spanning tree for each VLAN allowed on the trunks. Non-Cisco 802.1Q switches maintain only
one instance of spanning tree for all VLANs allowed on the trunks.
When you connect a Cisco switch to a non-Cisco device through an 802.1Q trunk, the Cisco switch
combines the spanning tree instance of the native VLAN of the trunk with the spanning tree instance
of the non-Cisco 802.1Q switch. However, spanning tree information for each VLAN is maintained
by Cisco switches separated by a cloud of non-Cisco 802.1Q switches. The non-Cisco 802.1Q cloud
separating the Cisco switches is treated as a single trunk link between the switches.
• Make sure the native VLAN for an 802.1Q trunk is the same on both ends of the trunk link. If the
VLAN on one end of the trunk is different from the VLAN on the other end, spanning tree loops
might result.
• Disabling spanning tree on any VLAN of an 802.1Q trunk can cause spanning tree loops.
Table 18-2 Layer 2 Ethernet Interface Default Configuration
Feature Default Value
Interface mode switchport mode dynamic auto
Trunk encapsulation switchport trunk encapsulation negotiate
Allowed VLAN range VLANs 1–1005
VLAN range eligible for pruning VLANs 2–1001
Default VLAN (for access ports) VLAN 1
Native VLAN (for 802.1Q only
trunks)
VLAN 1
STP
1
1. STP = Spanning Tree Protocol
Enabled for all VLANs
STP port priority 128
STP port cost
• 100 for 10-Mbps Ethernet LAN ports
• 19 for 10/100-Mbps Fast Ethernet ports
• 19 for 100-Mbps Fast Ethernet ports
• 4 for 1000-Mbps Gigabit Ethernet ports
• 2 for 10,000-Mbps 10-Gigabit Ethernet LAN ports

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