jheath@xxxxxxx writes:
> It looks like I misunderstood the way a multi-link bundle is negotiated
> via CCP. If they are separately negotiated,
RFC 1962:
2.1. Sending Compressed Datagrams
[...]
When using multiple PPP links to a single destination, there are two
methods of employing data compression. The first method is to
compress the data prior to sending it out through the multiple links.
The second is to treat each link as a separate connection, that may
or may not have compression enabled. In the second case, the PPP
Protocol field MUST be type hex 00FB (Individual link compressed
datagram).
RFC 1990:
5. PPP Link Control Protocol Extensions
[...]
Compression may be used separately on each member link, or run over
the bundle (as a logical group link). The use of multiple
compression streams under the bundle (i.e., on each link separately)
is indicated by running the Compression Control Protocol [5] but with
an alternative PPP protocol ID.
> as you say, then Individual
> Link Mode is not defined correctly. In fact that mode is probably not
> necessary at all since each link can negotiate and use Multi-Datagram
> mode, providing a history number is not needed to keep the links separate
> at the receiver.
Correct.
> Maybe the best thing would be to remove Individual Link Mode if multiple
> histories are not used in real PPP implementations anyway.
I can't say I've ever seen it used, except when doing testing. ;-}
The problem is that (in implementation) you need to have a reason to
want to use one history over another when deciding how to compress a
given packet. Other than hashing over the 5-tuple (and hoping that
the flows related to incompressible data cause only *some* of your
histories to thrash), I haven't seen any concrete ideas put forward.
Given the environments in which data compression is used (i.e., lower
speed links often associated with small numbers of users and flows),
it's not clear that there are important benefits to be gained.
--
James Carlson, Solaris Networking <james.d.carlson@xxxxxxxxxxxx>
Sun Microsystems / 1 Network Drive 71.234W Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757 42.497N Fax +1 781 442 1677
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