On Thu, 30 Jul 2009, byzek wrote:
It's not about performance; a large percentage of the currently-deployed hardware can¹t do UDP checksum calculations during encapsulation because it doesn¹t have access to the entire packet. Most hardware is streamlined to only provide the first n bytes of a packet to the forwarding engine, where typically n < 128.
I'm somewhat sympathetic to this concern, but I've been assured that it's possible to compute the outer checksum by doing an incremental checksum calculation (see e.g. RFC1624) using the inner packet's checksum. This would not require the access to the whole packet. This might work at least when encapsulating IPv4 over IPv6 UDP; I don't see how you could do this with IPv6 over IPv6 UDP due to the lack of "base" checksum. Any thoughts on how applicable this could be?
From the point of view of AMT specification, I don't see the need forIPv6 UDP encapsulation, even if you buy the LAG argument (I'm not sure if I can see 10G+ of traffic being LISP encapsulated between a couple of routers), it doesn't apply to AMT due to different traffic patterns.
-- Pekka Savola "You each name yourselves king, yet the Netcore Oy kingdom bleeds." Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
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