I have recently built a VPN for my company using a T1 that we also use for internet access. What I am trying to figure out is how much Bandwidth a VPN connection uses. I don't want to find myself in a postion where the VPN connections effect our ability to access the internet.
What type of device are you using to terminate your VPN tunnels? If you are using something like the 3005 concentrator, then you can login to the administrative console of the concentrator and it will show you how much bandwidth has been used on a session-by-session basis.
It is a good idea to enable QoS so that your bandwidth is properly allocated. Bandwidth usage is slightly higher because of the packet header size but I dont think its dramatic. The biggest issue is the processing power and it doesnt sound like you are even terminating the tunnels on the router so this shouldnt be a problem for you. Theres a good paper that discusses bandwidth among other things at http://www.cisco.com/warp/public/cc/so/cuso/epso/sqfr/safev_wp.htm
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...