[lug] Anyone with PPP multilink experience?

[Frank Whiteley]

----- Original Message -----
From: "Charles Morrison" <cmorrison at greeleynet.com>

> Harris, James wrote:
>
> >Howdy all --
> >
> >I've hit a new low of desperation for speed and am looking into multilink
> >PPP as an option.  Looks pretty do-able, and FRII supports it for $35/mo
> >total.  I can get work to pay for half the total cost of the two phone
lines
> >and the ISP charge, so overall, it seems like I could get a pretty decent
> >boost for cheap.  I'm wondering if anyone has any experiences that they
> >would be able to share with this type of setup; gotcha's, things to
> >consider, recommendations, additional reading, etc.?
> >
> I'm doing this with a SUSE distro. It works pretty well most of the
> time. I'm in an area where 21k is a really fast connection. using
> multilink gets me up to ~56k speeds sometimes. At less ideal times it at
> least keeps a slower connection up instead of dropping regularly.
>
> Let's see, setup. Make sure this is supported in your kernel, which is
> to say you have to rebuild it. Make sure you select the
> incomplete/development option or you'll never find it. I'm using NAT so
> I had to do a bunch of ther kernel tweaks too.
>
Multilink is poor man's ISDN;^)  There is about 0.3% loss in the binding to
a single session.  Using two Lucent chipset modems together is not
recommended.  USR chipsets work very well together.  No comment on Rockwell,
one way or the other.  Another expensive option is a 3COM multilink LAN
modem, which is priced about the same as their ISDN LAN modem at $340.
Webramp also has a LAN modem which can accept a second external modem.  It
will likely net for a little less.
> >
> >
> >My intent is to use the 2.4.x series of PPP and the kernel to get true
> >multilink support.  I'm still a bit unclear about some of the technical
info
> >surrounding multilink.  My biggest question is: can I down the second
> >portion of the bundle if I need to use the second phone line, or do both
> >portions of the bundle _always_ have to be up for it to work?
> >
> Yes, the second portion can go down without problem, although it may
> slow you down, but not the first.
>
> >
> >I'd love to hear any feedback that anyone would have to offer.  I've
looked
> >into ISDN and with the extra cost of the hardware and setup, it seems
like
> >multilink would be an acceptably cheaper alternative (I already have the
> >phone lines and second, matched V.90 modem avail.)  Right now I'm
> >consistently getting about 43k when I dialup, so x2 = wouldn't be bad.  I
> >understand that the latency won't improve, but that's what Squid and DNS
> >caching are for right?  :-)
> >
A few more comments for someone considering this.  The larger problem is
your Qwest service.  Adding lines has pitfalls, in that to bring you an
additional dial tone, Qwest may install a UDC to split your existing copper
into two (or more) numbers but trash your connect speeds.  That's CM's
issue, as he was getting 40K+ on a single line before he added the second
number.  The UDC uses DSL signaling to accomplish this.  Though the
equipment is capable of 64K per channel, it's detuned by Qwest at the C.O.
or SLC.  Depending on the era when you dwelling was built, it may only have
two or three pairs from the cable head.  The UDC's may be installed on the
dwelling or remotely on a pole.

If you have two or more lines capable of 40K+, then you'll get 80K+ plus
compression.  Two 50K+ analog connections may burst faster than 128K ISDN.
Expect 2x the slower connection WRT binding.  At 100K, multilink rocks and
rolls.

It's not necessary to match modems in all cases.  There may be some pitfalls
to mixing and matching as with Lucent and even that may be fixed by now.
Check the web sites.

There's a business in Wiggins that's been using four lines with multilink to
support about 15 workstations.  Your ISP should be able to allow as many
simultaneous connections as you are willing to pay for.  There are ISDN
routers that are four line capable(>$1200), but I'm not aware of similarly
designed LAN modems.

Frank Whiteley
Greeley