Every enterpries needs a remote access during roaming and vpnd is the best solution which can be used witout installing software on microsoft windows. This type of solutionis also known as ip dialing. For remote access laptop/pc should be connected to internet and able to reach the global internet ip address. If this option is available then its very easy to deploy the solution. I have tested it on a simple scenarion in which PC is connected via DSL and using simple PPTP(Point To Point Tunneling Protocol) to dial the public enterprise ip address.
Topology
PC—-DSL———–Internet———EnterpriseHO———Enterprise Network
In the above topolgy Enterprise HO router is enabled with VPDN(Virtual Dialup Network) so that it can work as LNS(Layer2 Nework Server). Now Remote PC will dial LNS public ip adress and after successfull authetication remote PC will be allocated with a public ip address and able to access its lan routers.
Authentication is done locally from router itself.
Configuration
int loopback 100
!Ip which is reahable from internet and remote PC will dial it
ip address 20.225.22.1 255.255.255.248
vpdn enable
vpdn-group 1
! Default PPTP VPDN group
accept-dialin
protocol pptp
virtual-template 5
local name CE_Router
interface Virtual-Template5
ip unnumbered Loopback100
peer default ip address pool TEST1
ppp authentication pap chap
ppp multilink
ip local pool TEST1 20.235.22.2 20.235.22.6
Explanation of each command
Vpdn enable – This command is used to make router as LNS.
accept-dialin – This command is used to accept dial services.
protocol pptp – This command is used to accept protocol as pptp during dialing which is used by microsoft PC.
virtual-template 5 – This command is used to bind virtual template 5 with vpdn-group1 becasue after dialing virtual access interface will come up.
local name – Host name will be used here.
ip local pool TEST1 – A pool with ip addresses as configured. It means only 5 persons can dial and able to access the lan from outer cloud.
Virtual template
peer default ip address pool TEST1 – Afer successful authentication ip address will be given form pool TEST1
ppp authentication pap chap – This command is used for autheication.