As some of you can tell I'm on a VPN-related kick lately. Sorry. I just finished reading an interview with Luca Martini and that got me interested in finding out more about L2 VPNs. I'm already getting fairly familiar with RFC 2764-style L3 VPNs, particularly Qwest's PRN offering. After reading the interview I checked into Level3's (3)Packet Data Services solution and it seems to be pretty cool, as well. However, I'm still leaning toward L3 VPNs and here's why.
Right now we have a frame relay network where most of our locations has at least two or three PVCs and sometimes as many as four or five that carry the bulk of their traffic. When considering a move to VoIP or expanded video conferencing this can create some traffic shaping issues. For example, in frame relay you want to shape your traffic such that no PVC can burst over its CIR. If you have three PVCs that limits each of them to 512k even when no critical traffic is present! This is not flexible, and during our VoIP testing it really irritated our LAN group who were used to transferring large amounts of data at night to these locations. As I understand L2 VPNs, at least the Martini/Level3 variety, we'd still end up with a large, hub-and-spoke, point-to-point network and hence would have similar traffic shaping issues. Perhaps the big benefit is that we don't have the CIR limitation so we might not have to be so restrictive with our traffic shaping. In fact, traffic shaping might not be necessary; LLQ might be all that is necessary. I'll have to ponder that some more. Regardless, with a 2764-style VPN like the Qwest PRN we'd end up with a fully-meshed network where all nodes appear to be one-hop away from all other nodes. It's a multipoint solution where each location gets to use the full access pipe into the network without worrying about shaping or queueing on a per-PVC basis. Since we're still considering moving to IP Telephony and we're expanding our use of video conferencing this provides some amazing benefits from a functional perspective but it also greatly reduces the complexity of our router configuration. There are some operational trade-offs but I think those are workable. My feeling after spending a few days reading about this is that given a moderately large hub-and-spoke network, a L3 VPN might be of more benefit than a L2 VPN. Any thoughts? Thanks, John Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=73255&t=73255 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
