The tunnel Id of the VPDN group.
For Cisco IOS 12.05T and later, the tunnel id matches
the remote name configured on the HGW router. The
following is an example:
vpdn-group 1
accept dialin l2tp virtual-template 1 remote isp1
local name hg
For old Cisco IOS releases, the tunnel id matches the
incoming statement:
vpdn incoming isp1 hgw virtual-template 1
In above examples, the object has the value isp1.