Consequently, the ability of VPN to scale on a remote user basis is dependent upon the amount of system memory installed in the gateway. Additional memory could enable a VPN-1 Gateway to support more that 4,500 tunnels. However, most VPN deployments will run into throughput limitations far before reaching 4,500 remote user tunnels. For example, at an average of 10K per remote user, the bandwidth required to support 4,500 remote users is 45 Mbps. In a site to site VPN deployment, many users share a single tunnel between two VPN gateways.
Many users can establish multiple connections through the same tunnel.
Scaling Concurrent Connections between Hosts As in the case of remote users, the ability of VPN-1 to support a large number of host connections between VPN gateways is dependent upon the amount of system memory installed in each VPN gateway. VPN Quality of Service Delivering sufficient data throughput and concurrent connection support does not guarantee reliable VPN performance. An organization could have more than enough VPN processing power but still experience poor performance as a result of congestion on shared Internet links. Too often, bandwidth hungry discretionary traffic overwhelms business critical traffic on these links. Over provisioning Internet bandwidth is not a viable, long-term solution to congestion problems.