7-11
Cisco SCE 8000 10GBE Software Configuration Guide
OL-30621-02
Chapter 7 Configuring Line Interfaces
Tunneling Protocols
Disabling the L2TP Tunneling
Disables all IP tunnels except IPinIP and GRE.
Step 1
Shut down the linecard. (This is a root level command.)
From the SCE(config if)#> prompt, enter
shutdown
and press
Enter
.
Step 2
Disable L2TP tunneling.
From the SCE(config if)#> prompt, enter
no ip-tunnel l2tp skip
and press
Enter
.
Step 3
Restart the linecard.
From the SCE(config if)#> prompt, enter
no
shutdown
and press
Enter
.
Configuring GRE Tunneling
•
Enabling GRE Tunneling, page 7-11
•
Disabling GRE Tunneling, page 7-12
GRE tunneling is an IP-based tunneling protocol; therefore the system must be specifically configured
to recognize the flows inside the tunnel. The Cisco SCE platform will then skip the external IP header,
reaching the internal IP, which is the actual subscriber traffic. When GRE skip is disabled, the system
treats the external IP header as the subscriber traffic, resulting in all GRE traffic being reported as
generic IP.
Guidelines for configuring GRE tunnels:
•
GRE and other tunnels: GRE tunnels are supported simultaneously with plain IP traffic and any
other tunneling protocol supported by the Cisco SCE platform.
•
Overlapping IP addresses: There is no support for overlapping IP addresses within different GRE
tunnels.
•
DSCP marking: For GRE traffic, DSCP marking can be done on either the external or the internal
IP header exclusively. (See
“Configuring DSCP Marking” section on page 7-14
Caution
IP tunneling can be configured (enabled, disabled or DSCP marking configuration) only when there is
no application loaded or the linecard is shut down.
Fragmentation
Fragmentation should be avoided whenever possible. If it is not possible to avoid fragmentation, it is
recommended to opt for internal fragmentation. If that is also not possible, the Cisco SCE platform can
be operated under conditions of external fragmentation.
Enabling GRE Tunneling
By default, IP tunnel recognition is disabled. Use this command to configure recognition of GRE tunnels
and skipping into the internal IP packet.
Step 1
Shut down the linecard. (This is a root level command.)
From the SCE(config if)#> prompt, enter
shutdown
and press
Enter
.