Cisco WS-C6506 Software Manual page 1439

Configuring the MSFC Cisco IOS Features
This chapter describes the Cisco IOS features that are used with the Catalyst operating system to provide
feature functionality and parity between these operating systems.
These sections describe the Cisco IOS features that are used with the Catalyst operating system:
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IP-in-IP Tunneling
IP-in-IP tunneling allows a mobile host to move between networks without changing its IP address.
IP-in-IP tunneling allows an IPv4 datagram to be encapsulated within another IPv4 datagram and carried
as a payload to its destination. This IPv4 within IPv4 encapsulation is a type of Generic Routing
Encapsulation (GRE) that is similar to GRE tunneling.
The PFC3 and DFC3s support the following tunnel commands:
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Other supported types of tunneling are run in the software on the MSFC3.
Enter the tunnel ttl command (default 255) to set the TTL of encapsulated packets.
Enter the tunnel tos command, if present, to set the ToS byte of a packet when it is encapsulated. If the
tunnel tos command is not present and you do not enable QoS, the ToS byte of a packet sets the ToS
byte of the packet when it is encapsulated. If the tunnel tos command is not present and you enable QoS,
the ToS byte of a packet as modified by PFC QoS sets the ToS byte of the packet when it is encapsulated.
To configure GRE tunneling and IP-in-IP tunneling, refer to these URLs:
http://www.cisco.com/en/US/docs/ios/12_2/interface/configuration/guide/icflogin.html
To configure the tunnel tos and tunnel ttl commands, refer to this URL:
http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/12s_tos.html
OL-8978-04
IP-in-IP Tunneling, page 56-1
WCCP, page 56-2
tunnel destination
tunnel mode gre
tunnel mode ipip
tunnel source
tunnel ttl
tunnel tos
C H A P T E R
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
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56-1