HP Cisco Nexus 5000 Cisco Nexus 5000 Series Switch CLI Software Configuration - Page 216

Understanding Allowed VLANs, Configuring Access and Trunk Interfaces, Configuring a LAN Interface

Page 216 highlights

Configuring Access and Trunk Interfaces Chapter 12 Configuring Access and Trunk Interfaces Send feedback to [email protected] A trunk port can carry untagged packets simultaneously with the 802.1Q tagged packets. When you assign a default port VLAN ID to the trunk port, all untagged traffic travels on the default port VLAN ID for the trunk port, and all untagged traffic is assumed to belong to this VLAN. This VLAN is referred to as the native VLAN ID for a trunk port. The native VLAN ID is the VLAN that carries untagged traffic on trunk ports. The trunk port sends an egressing packet with a VLAN that is equal to the default port VLAN ID as untagged; all the other egressing packets are tagged by the trunk port. If you do not configure a native VLAN ID, the trunk port uses the default VLAN. Understanding Allowed VLANs By default, a trunk port sends traffic to and receives traffic from all VLANs. All VLAN IDs are allowed on each trunk. However, you can remove VLANs from this inclusive list to prevent traffic from the specified VLANs from passing over the trunk. You can add any specific VLANs later that you may want the trunk to carry traffic for back to the list. To partition spanning tree protocol (STP) topology for the default VLAN, you can remove VLAN1 from the list of allowed VLANs. Otherwise, VLAN1, which is enabled on all ports by default, will have a very big STP topology, which can result in problems during STP convergence. When you remove VLAN1, all data traffic for VLAN1 on this port is blocked, but the control traffic continues to move on the port. Configuring Access and Trunk Interfaces This section includes the following topics: • Configuring a LAN Interface as an Ethernet Access Port, page 12-4 • Configuring Access Host Ports, page 12-5 • Configuring Trunk Ports, page 12-6 • Configuring the Native VLAN for 802.1Q Trunking Ports, page 12-6 • Configuring the Allowed VLANs for Trunking Ports, page 12-7 Configuring a LAN Interface as an Ethernet Access Port You can configure an Ethernet port as an access port. An access port transmits packets on only one, untagged VLAN. You specify which VLAN traffic that the interface carries. If you do not specify a VLAN for an access port, the interface carries traffic only on the default VLAN. The default VLAN is VLAN1. The VLAN must exist before you can specify that VLAN as an access VLAN. The system shuts down an access port that is assigned to an access VLAN that does not exist. To configure an Ethernet access port, perform this task: Step 1 Step 2 Command switch# configure terminal switch(config)# interface {{type slot/port} | {port-channel number}} Purpose Enters configuration mode. Specifies an interface to configure, and enters interface configuration mode. 12-4 Cisco Nexus 5000 Series Switch CLI Software Configuration Guide OL-16597-01

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Send feedback to [email protected]
12-4
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01
Chapter 12
Configuring Access and Trunk Interfaces
Configuring Access and Trunk Interfaces
A trunk port can carry untagged packets simultaneously with the 802.1Q tagged packets. When you
assign a default port VLAN ID to the trunk port, all untagged traffic travels on the default port VLAN
ID for the trunk port, and all untagged traffic is assumed to belong to this VLAN. This VLAN is referred
to as the native VLAN ID for a trunk port. The native VLAN ID is the VLAN that carries untagged traffic
on trunk ports.
The trunk port sends an egressing packet with a VLAN that is equal to the default port VLAN ID as
untagged; all the other egressing packets are tagged by the trunk port. If you do not configure a native
VLAN ID, the trunk port uses the default VLAN.
Understanding Allowed VLANs
By default, a trunk port sends traffic to and receives traffic from all VLANs. All VLAN IDs are allowed
on each trunk. However, you can remove VLANs from this inclusive list to prevent traffic from the
specified VLANs from passing over the trunk. You can add any specific VLANs later that you may want
the trunk to carry traffic for back to the list.
To partition spanning tree protocol (STP) topology for the default VLAN, you can remove VLAN1 from
the list of allowed VLANs. Otherwise, VLAN1, which is enabled on all ports by default, will have a very
big STP topology, which can result in problems during STP convergence. When you remove VLAN1,
all data traffic for VLAN1 on this port is blocked, but the control traffic continues to move on the port.
Configuring Access and Trunk Interfaces
This section includes the following topics:
Configuring a LAN Interface as an Ethernet Access Port, page 12-4
Configuring Access Host Ports, page 12-5
Configuring Trunk Ports, page 12-6
Configuring the Native VLAN for 802.1Q Trunking Ports, page 12-6
Configuring the Allowed VLANs for Trunking Ports, page 12-7
Configuring a LAN Interface as an Ethernet Access Port
You can configure an Ethernet port as an access port. An access port transmits packets on only one,
untagged VLAN. You specify which VLAN traffic that the interface carries. If you do not specify a
VLAN for an access port, the interface carries traffic only on the default VLAN. The default VLAN is
VLAN1.
The VLAN must exist before you can specify that VLAN as an access VLAN. The system shuts down
an access port that is assigned to an access VLAN that does not exist.
To configure an Ethernet access port, perform this task:
Command
Purpose
Step 1
switch#
configure terminal
Enters configuration mode.
Step 2
switch(config)#
interface
{{
type
slot
/
port
} | {
port-channel
number
}}
Specifies an interface to configure, and enters interface
configuration mode.