05-23-2011 10:34 PM - last edited on 05-24-2011 09:09 AM by Vince_02
Dropped VPN connections
I experienced a similar issue a few years ago with my LinkSys WRT54G router with dropped connections to my corporate network using the Cisco VPN Client. To make a long story short the problem was the result of the following:
1. The default ""Client Lease Time" on LinkSys routers is 0 which means 1 day or 24 hours.
2. By DHCP Protocol definition, DHCP clients must renew the DHCP client IP address lease at the 1/2 life cycle
of the lease (12 hours if using the router's default setting). This is deadly for VPN clients as the short period
of time when the client IP address is no longer valid, the VPN client considers this a loss of network connection.
The LinkSys E-series routers further aggravate the situation by randomly assigning new IP addresses to
DHCP clients instead of reassigning the client's previous IP address and tends to favor higher host IP addresses
in the defined range.
Suggestions to prevent lost VPN client connections:
1. Change the "Client Lease Time" on the router to 8640 minutes (6 days 00:00:00).
2. Prior to establishing a VPN client connection, use the Windows Command Prompt to issue the "ipconfig /renew"
command to obtain a new IP address from the router that will be good for 3 days (72 hours).
3. Configure your E-series router to use the <DHCP Reservation> option to pre-assign IP addresses to your systems
making sure they are outside the range of the dynamically assigned DHCP addresses. Using default settings,
these would be in the range of 192.168.1.2 thru 192.168.1.99 as the router starts at 192.168.1.100 thru
192.168.1.149. This will guarantee you system will get the same IP address at all renewals.
(Mod note: Thank you for the suggestion. We made this a sticky for other users to see. Kudos to you!)
12-26-2011 04:57 AM
VPN is a network that uses primarily public telecommunication infrastructure, such as the Internet, to provide remote offices or traveling users access to a central organizational network.
VPNs may serve any network functionality that is found on any network, such as sharing of data and access to network resources, printers, databases, websites, etc.