RE: OT : Multi ISP connections...

["Mark Harrison" <Mark.Harrison@xxxxxxx>]

Not quite, I'm afraid ;-)


The IP protocol was designed to support diverse routing by the addition
of other parts of the TCP/IP protocol suite such as RIP and its friend
(TRIP etc.) In practice, this additional stuff is only implented to
"hardcore" routers.

The problem you will have is that your (Phil's) PC will be presenting
two different IP addresses to the connected internet. One allocated by
each ISP for that dial-up connection.

As such, the server responding to the request "host with ip address
a.b.c.d wants to download file.name" has no way of knowing that the
other request from ip address e.f.g.h is, in fact, coming from the same
box.

In order to get the full aggregation, the WAN ports on both ISDN
channels need to be able to talk (RIP or whatever) to the same "Router
Pool". In practice, for dial-up ISPs, this means dialing both up to
the
SAME ISP.

It is very unlikely that two different ISPs would pass their end-users
IP addresses onto each other. Instead they'll use direct routing based
around allocated blocks, and dynamic next-hop stuff is more an issue for
backbone providers than local ISPs.


What may well be possible, however, is that Phil can use one connection
to do the single download, and use the other to carry on surfing as if
there was nothing else on the line. That single download will still take
just as long, but it won't make the PC feel "tied up".

This would take a bit of buggering around in the innards of Control
Panel/Networks (for a separate ISDN TA / Modem pair, or for a
single-channel router / modem pair), or the innards of the router... but
is possible.

The nice thing about surfing - well about the http protocol - is that
each "object" (page, or graphic / object on a page) is done as a
separate connection, so it does matter if 5 of the graphics on your site
come down one pipe, and 5 down the other - the "site" doesn't
realise
that they're the same PC, but doesn't care... (This is less true for
some of the fancier sites that make heavy, but naive, use of Cookies,
BTW!)


Sorry to those who didn't follow that if I've explained this badly...
even more apologies to those who DO understand this, and have been
wincing at every massive over-simplification ;-)


Mark Harrison
Head of Systems, eKingfisher

-----Original Message-----
From: Paul Gordon [mailto:paul_gordon@xxxxxxx]
Sent: 20 December 2001 08:41
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] OT : Multi ISP connections...


>
>To be honest, I doubt bonding across different ISPs would work without
>something at the other end performing the appropriate tasks for
splitting
>transmission across the two channels so I suspect you would end up with
two
>64K connections rather than one 128K connection anyway. Might work OK
for
>multiple downloads I suppose.
>


The way the internet and the TCP/IP protocols are designed is to fully
support and expect fragmentation and multiple routes for a connection,
so as
long as you can get two internet connections running simultaneously on
your
PC, the only "bonding" or aggregation that needs to take place is
there.
(on
YOUR PC that is..) - The web server (or whatever) at the other end does
not
need to know or care that you have multiple connections, even if they
are
through different ISPs..

So, there's no reason why this should not work as intended (AFAIK).  -
I.E.
2 64K connections to two different ISP's, aggregated at your end into a
single 128K pipe that you can then use as if it were a single 128K
connection..

As ever, all is AFAIK, so could be total arse!

Paul G.


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