On Mar 6, 2008, at 10:11 AM, Bengt Ahlgren wrote:
"William Herrin" <bill@herrin.us> writes:Loose and strict source routing existed in IPv4 for a reason. Therewere some security issues, some performance issues and the network gotwider than they could support but they weren't fundamentally a bad idea. Indeed, if loose source routing was still valid, our map-encap schemes might not need the encap part at all.This is IMO an important point. You can get the same function as a tunnel, but without requiring the other end to decap. In NIIA we call it routing hint, but it has basically the same function.
You can also avoid certain path MTU issues of tunnels, all while making the underlying intentions for the packet more visible / explicit.
I think some folks may equate tunnel endpoints with "a small number of specifically configured routers", and source routing with "no control because any router could be a source routing way-point". This is really a question of the usage model, though, not an inherent property of tunneling vs. source routing mechanisms. I think you could use source routing in a controlled way as well, where only a small number of specifically configured nodes are configured to act as way-points.
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