3Com Switch 8800 Family IPsec Module Configuration and Command reference Guide

360 CHAPTER 21: GRE CONFIGURATION COMMANDS
upon the expiration of a specified period, the SecBlade resends the keepalive
packet. If no response is received yet after the number of resending attempts
exceeds the specified limit, the protocol of the local tunnel interface goes down.
Related command: interface tunnel.
Example
# Configure the security gateway to send GRE keepalive messages up to five times
at intervals of 20 seconds.
[SecBlade_VPN-Tunnel0] keepalive 20 5
source Syntax
source { ip-addr | interface-type interface-num }
undo source
View
Tunnel interface view
Parameter
ip-addr: Specifies IP address of the real interface sending GRE packets in the
address format of A.B.C.D.
interface-type interface-num: Specifies the real interface sending packets by
specifying its interface name and number.
Description
Use the tunnel source command to specify the source IP address to be filled in
the added IP header at the time of tunnel interface encapsulation.
Use the undo tunnel source command to delete the defined source address.
By default, source address of tunnel is not specified in the system.
The specified source address of the tunnel is the real interface address sending
GRE packets, which should keep accordance with the specified destination
address at the opposite tunnel interface.
The same source address and destination address cannot be configured on two or
more tunnel interfaces using the same encapsulation protocol.
Related command: interface tunnel, destination.
Example
# Configure the interface Tunnel5 on SecBlade_VPN1, on which the physical
output interface of the encapsulated packet is GigabitEthernet0/0.1 (with the IP
address of the interface being 192.100.1.1).
[SecBlade_VPN1-Tunnel5] source 192.100.1.1
Alternatively, you may specify the actual physical interface:
[SecBlade_VPN1-Tunnel5] source GigabitEthernet0/0.1