[Bloat] Random idea in reaction to all the discussion of TCP flavours - timestamps?

Jonathan Morton chromatix99 at gmail.com
Wed Mar 16 19:23:11 EDT 2011


On 17 Mar, 2011, at 12:48 am, Fred Baker wrote:

>> This reminds me of a related concept, using the TTL really as 'Time To Live' (in today's IP, it's more of a 'Remaining Hop Count). According to RfC 791, a router that buffers a packet by n seconds must decrease its TTL by n. I doubt that many routers implement this properly.
> 
> There is, of course, a fundamental bug in that, noted in RFC 970.
> 
> RFC 1812, which I edited, contains this text (that I didn't write):
> 
>      In this specification, we have reluctantly decided to follow the
>      strong belief among the router vendors that the time limit
>      function should be optional.

The major problem with the original TTL spec was that a router generally doesn't keep a packet for an integer number of seconds (at least, not in anything but the most ancient of hardware).  If three separate routers each buffer for 350ms, that's about 1 second elapsed, but there is no way for the routers to indicate this to each other.  Yet the TTL field was an integer number of seconds.

The later hop-count spec is much saner.

 - Jonathan




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