VPNs using two T1s & CEF

vpoon87 · ‎11-10-2008

Hi All,

We are looking into getting two T1 lines and bonding them using CEF. Our primary use for these T1s is VPN usage. Our ISP is saying that there could be problems if we bonded them together on one router using CEF. Has anyone had problems with this type of configuration?

Thanks

VP

Richard Burts · ‎11-10-2008

VP

Perhaps it might help to clarify some terminology. Most of the time when people talk about bonding T1s they are talking about using PPP Multilink. When they talk about CEF it is ususally for Load Sharing or Load Balancing. So perhaps you could clarify which one you are talking about?

IPSec which is usually the foundation of VPN does check incoming packets and out of order packets can be an issue since IPSec is checking to be sure that someone is not intercepting or modifying packets going through the VPN. Since there is some opportunity for out of order packets when Load Sharing over T1s I would think that it might be somewhat more safe to use PPP Multilink for the VPN connection.

HTH

Rick

HTH

Rick

vpoon87 · ‎11-10-2008

Hi Rick,

Thanks for the prompt reply and clarification.

It looks like my ISP will just be using CEF and not PPP Multilink. Should I find an ISP that will provide a PPP Multilink connection instead?

VP

Richard Burts · ‎11-10-2008

VP

I am not sure that the difference between using PPP Multilink or using CEF is important enough to be worth changing providers. If it were in the selection process it might be interesting to compare providers based on whether they support PPP Multilink or not. But once the provider is selected I am not sure it is worth trying to change over this question.

HTH

Rick

HTH

Rick