12-17
Cisco Systems IntelligentGigabit Ethernet Switch Modules for the IBM BladeCenter, Software Configuration Guide
24R9746
Chapter12 Configuring VLANs
Configuring VLAN Trunks
Default Layer 2 Ethernet Interface VLAN ConfigurationTable12-5 shows the de fault Layer 2 Ethernet interface VLAN configuration.
Configuring an Ethernet Interface as a Trunk PortBecause trunk ports send and receive VTP advertisements, to use VTP you must ensure that at least one
trunk port is configured on the switch and is connected to the trunk port of a second switch. Otherwise,
the switch cannot receive any VTP advertisements.
This section includes these procedures for configuring an Ethernet inte rface as a trunk port on the switch:
•Interaction with Other Features, page 12-18
•Defining the Allowed VLANs on a Trunk, page 12-19
•Changing the Pruning-Eligible List, page 12-20
•Configuring the Native VLAN for Untagged Traffic, page 12-21
Note The default mode for external interfaces is switchport mode dynamic desirable interface configuration
mode. If the neighboring interface supports trunking and i s configured to allow trunking, the link is a
Layer 2 trunk.
Table12-5 Default Layer 2 Ethernet Interface VLAN Configuration
Feature Default Setting
Interface mode trunk on the internal ports (ports 1 to 16).
dynamic desirable on the external ports (ports 17
to 20).
Allowed VLAN range VLANs 1 to 4094.VLAN ID range is 2 to 4094 on
the internal 1000 Mbps ports (ports 1 to 14).
VLAN ID range is 1 on the internal 100 Mbps
management module ports (ports 15 to 16).
VLAN ID range is 1 to 4094 on the external ports
(ports 17 to 20).
VLAN range eligible for pruning VLANs 2 to 1001
Default VLAN (for internal 100 Mbps
management module ports)
VLAN 1
Default VLAN (for external ports and
internal 1000 Mbps ports)
VLAN 2
Native VLAN (for IEEE 802.1Q trunks) VLAN 1 (for internal 100 Mbps management
module ports)
VLAN 2 (for external ports and internal 1000 Mbps
ports)