Default Layer 2 Ethernet Interface Configuration - Cisco Catalyst 4500 Series Software Configuration Manual

Default Layer 2 Ethernet Interface Configuration

Default Layer 2 Ethernet Interface Configuration
Table 19-2
Table 19-2
Feature
Interface mode
Trunk encapsulation
Allowed VLAN range
VLAN range eligible for pruning VLANs 2–1001
Default VLAN (for access ports) VLAN 1
Native VLAN (for 802.1Q only
trunks)
STP
STP port priority
STP port cost
1. STP = Spanning Tree Protocol
Layer 2 Interface Configuration Guidelines and Restrictions
When using (or configuring) Layer 2 interfaces, consider these guidelines and restrictions:
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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
19-4
shows the Layer 2 Ethernet interface default configuration.
Layer 2 Ethernet Interface Default Configuration
1
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.
Chapter 19
Default Value
switchport mode dynamic auto
switchport trunk encapsulation negotiate
VLANs 1–1005
VLAN 1
Enabled for all VLANs
128
• 100 for 10-Mbps Ethernet LAN ports
• 19 for 10/100-Mbps Fast Ethernet ports
19 for 100-Mbps Fast Ethernet ports
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4 for 1000-Mbps Gigabit Ethernet ports
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2 for 10,000-Mbps 10-Gigabit Ethernet LAN ports
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Configuring Layer 2 Ethernet Interfaces