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| Broadband and Dial up. |
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| message from Donald McTrevor on 27 Jun 2005 |
Is this possible?
When mine (brooadband) was installed I was told to delete all my dialup
connection entries (against my wishes) however I have added
some since, but not used them.
Can I use them or will it confuse my computer?
Could I just plug in my telephone modem now and dial one up
(whilst still connected by my cable modem) or would I
have to disconnect the cable modem (which causes my
computer to crash, I believe).
I guess I could try but, that would cost a few pence :O)
Cheaper to ask.
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| Alex Monro replied to Donald McTrevor on 28 Jun 2005 |
Unless you set up some special routing to split your traffic between cable
& dialup you're likely to get things very confused. You don't say what
OS you're using, but I believe most versions of Windows can't handle
routing very well. I tried something similar with Linux once, but I
didn't manage to get it to work.
It might be worth keeping the dialup connections & modem as a backup in
case the cable modem fails sometime.
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| AnthonyL replied to Alex Monro on 28 Jun 2005 |
I regularly do a dial-up to one particular ISP whilst connected on
broadband to a different ISP. (I have a small web site on the dial-up
ISP). With nothing especially setup the dial-up connection seems to
take precedence. My broadband connection uses a network card.
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| Donald McTrevor replied to AnthonyL on 28 Jun 2005 |
I am using windows98,
I thought that this might be possible.
There is nothing in theory as to why it should not happen.
(barring microsoft et all being shhhhite).
Not sure what you mean my takke precedence, both can exist
at the same time?
It is always useful to have a backup.
I will give it a try sometime.
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| AnthonyL replied to Donald McTrevor on 29 Jun 2005 |
The connection uses the dial-up route rather than the broadband route.
It is actually what I want because I can only amend my website if I am
connected via the dial-up ISP. I used to go to the trouble of
disabling my network connection and dialling up until I realised it
was not necessary.
I read somewhere else (in this thread) that the most recent connection
takes precedence though I have not tested it.
Setting the metric in the route table could force different
destinations to use your choice of connection but exactly how to do
that is beyond me.
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| Jim Howes replied to AnthonyL on 29 Jun 2005 |
I'm not a fan of windows routing, but each connection will establish a
default route, which would make the most recent connection take precedence.
Windows does have a route command, but it's syntax is particularly
crufty. It should be possible, if you know all of the IP addresses
involved, to tell the system to route packets to the web server over the
dialup link, and maintain a default route via your ADSL router/modem.
There is documentation in windows help on the route command, but having
read it, I find myself needing to go and make a very large drink...
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| AnthonyL replied to Jim Howes on 29 Jun 2005 |
I was on a site which had two broadband connections. One was for
general use and the other specifically intended for incoming VPN.
However if the main connection on the 192.168.1.x network was down I
could force myself onto the other (192.168.0.x) connection using:
route add -p 192.168.0.0 mask 255.255.255.0 192.168.1.250
-p makes it permanent
where 192.168.1.250 was the router.
I can't recall if I had to change my IP to suit but I suspect I did.
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| John Ewing replied to Alex Monro on 28 Jun 2005 |
[snip]
Also very useful to get on to your ISP's website to find out if a
connectivity problem is at their end.
John
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| Donald McTrevor replied to Donald McTrevor on 30 Jun 2005 |
Because I could only partially read my NTL installation disk I had to call
the
support line for assistance, there were still some problems which is when,
I think, he told be to delete all my dial up connections, so I could hardly
refuse especially as he was rather bossy "Just DO as I say..!".
The installition was sort of hacked togeather as I could not read all the
files on the disk.
It works fine now,one or two probs but I have always be able to recover
from them quickly do it was probably something at my end.
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| Colin Wilson replied to Donald McTrevor on 28 Jun 2005 |
Certainly possible. Both at the same time if you so wish.
The guy was a muppet.
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| Martin Underwood replied to Colin Wilson on 28 Jun 2005 |
Indeed he was. The only dialler entry that would become superfluous (but
it's OK to keep it there) is one which dials to a freephone number, because
most ISPs remove your access to this at the same time as upgrading you to
broadband. However you retain the ability to dial up on a pay-as-you-go
number.
I'm not too sure how TCP would react if you had a broadband and a dialup
session at the same time. It would probably do one of two things: a)
initally send packets over both transports and learn that it always got a
faster response over broadband and so use it; or b) send packets randomly
according to which transport had no packets queued to send, thus sending
most data over broadband and occasional packets over dialup. It's a similar
situation to a PC with both a cable and a wireless link to a router (eg take
your PC which has a wireless link established and plug it into a LAN) - I
imagine traffic ends up being sent mainly or exclusively over the faster
link.
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| Donald McTrevor replied to Martin Underwood on 28 Jun 2005 |
Yes I recall there is some 7 layer model for comms, although only a few
may be used, its quite a compliacted thing which I would have thought
would cover things like this but... I guess if you have two lines of
communication open things get rather confusing as there is no way you
can specify which 'link' to use.
Obviously with dial up you can hang up, but with a cable modem its not
so simple. I seem to recall that if I disconnect the cable modem it
causes major problems essentially 'disable' the computer entirely.
I am not sure if this would happen if I had a dial up conection at the
same time.
Also I doon't think my computer will boot properly if the cable modem
is disconnected. Probably a way around that (one would hope!! (new PC? -
lol))
I will have to look into it and try a few thing out sometime.
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| Colin Wilson replied to Martin Underwood on 28 Jun 2005 |
I tried it a while ago, and IIRC, the "newest" connection took precedence
on Win98SE
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| Donald McTrevor replied to Colin Wilson on 28 Jun 2005 |
It might be sensible to close any open connections I suppose.
Things could get awefully confusing, you would have two domain
name servers for instance......
I seem to recall the names of some layers were call the physical,
session, transport, appllication?... anyway google gives...
http://www.freesoft.org/CIE/Topics/15.htm
although I am not sure how it all hangs togeather and whether or where
this situation is covered.
Still not a major problem anyway.
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| Donald McTrevor replied to Donald McTrevor on 28 Jun 2005 |
actually....
" it's the danger of IETF turning into another ISO - a big, overgrown
standards
organization run by committees, churning out thousands of pages of rubbish"
Thats the impressioni I have alway got from reading about it!!! lol.
Ah the joys of electrical engineering, worse than newsreading!!
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| Donald McTrevor replied to Colin Wilson on 28 Jun 2005 |
True I kind of realised this, however I had little choice but to
follow his instructions, especially as there could have been a
genuine reason for this.
I guess leaving me with no backup connection it would make
me more reliant on there suppport (presumably at premium rates).
However I have not really needed a backup so far but I don't want
to put all my eggs in one basket.
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| "David G. Bell" replied to Donald McTrevor on 29 Jun 2005 |
On Tuesday, in article
I'm going by hazy recollection of some reading I once did.
The 7-layer model (and variants -- I don't know of any widely used
system that use the 7-layers of theory) doesn't really matter to this.
But there are layers, and all this stuff is sorted out lower down, where
the user doesn't usually look.
Anyway, here's my summary:
A computer can have multiple network connections, and each will have its
own IP address.
Usually there are rules which specify which ranges of IP addresses are
connected to which network connection. A box running as a firewall is
an example of this: two ethernet ports, two IP addresses, two networks.
A router is doing some of the same.
But two different network connections can cover an overlapping range of
addresses. There are ways of specifying the "cost" of the alternative
routes to the same IP address.
Connecting to a dial-up ISP to collect email is going to allow an
overlap, but it's possibly enough to describe that connection as only
being connected to the DUISP's address space. And you could still use
the DUISP's DNS server. It's converting a domain name to an IP address,
and you're deciding just how you make the connection. Different
layers...
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