Configuring a tunnel interface
Configure a Layer 3 virtual tunnel interface on each device on a tunnel so that devices at both ends can
send, identify, and process packets from the tunnel.
Configuration guidelines
Follow these guidelines when you configure a tunnel interface:
Before configuring a tunnel interface on a switch, you may need create a service loopback group
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with its service type as Tunnel, and add unused Layer 2 Ethernet interfaces of the switch to the
service loopback group.
On the switch, an encapsulated packet cannot be forwarded a second time at Layer 3 by using the
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destination address and routing table, but is sent to the loopback interface, which then sends the
packet to the forwarding module for Layer 3 forwarding. You must reference a service loopback
group on the tunnel interface. Otherwise, the tunnel interface will not be up and packets cannot be
transmitted over the tunnel. For creation and configuration of a service loopback group, see Layer
2—LAN Switching Configuration Guide.
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The tunnel bandwidth command does not change the actual bandwidth of the tunnel interface, but
sets a bandwidth value for dynamical routing protocols to calculate the cost of a tunnel path. You
can determine the value according to the bandwidth of the output interface.
You must configure a MTU no smaller than 1280 bytes for the tunnel (such as an IPv6 over IPv4
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tunnel or an IPv6 over IPv6 tunnel).
Configuration procedure
To configure a tunnel interface:
Step
1.
Enter system view.
2.
Create a tunnel
interface and enter its
view.
3.
Configure the
description for the
interface.
4.
Reference a service
loopback group.
5.
Set the MTU of the
tunnel interface.
Command
system-view
interface tunnel number
description text
service-loopback-group number
mtu mtu-size
125
Remarks
N/A
By default, no tunnel interface is created.
Optional.
By default, the description of a tunnel
interface is Tunnelnumber Interface.
By default, the tunnel does not reference
any service loopback group.
Optional.
64000 bytes by default.
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An MTU set on any tunnel interface is
effective on all existing tunnel
interfaces.
•
You can issue this command multiple
times, but only the last configuration
takes effect.