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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

RFC1483 Bridged vs Bridged Mode Only



 
 
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  #1  
Old May 21st 06, 02:57 PM posted to uk.telecom.broadband
Simon Dean
external usenet poster
 
Posts: 58
Default RFC1483 Bridged vs Bridged Mode Only

When connecting my ethernet modem to my smoothwall router/firewall,
could someone please explain, on the modem, what the difference is
between RFC1483 Bridged and Bridged Mode Only?

Which ones can be used in the UK?

You see, I keep coming back to the fact that in the UK, we're PPPoA, but
when you want to connect your modem to your router, you can't specify
PPPoA, it's RFC1483 Bridged, or Bridged Mode Only.

In Bridged Mode Only, we get to use PPPoE to authenticate from our
router, our Linux box, or our Windows XP, as suggested he
http://www.adslguide.org.uk/hardware...nksysADSL2.asp

So then presumably, rather than connecting by PPPoA, we go by PPPoE
because the computer takes control of the connection.

I've seen references for RFC 1483 - Multiprotocol Encapsulation over ATM.

So then I start to wonder, what does that mean? If we set up in RFC1483,
will the modem convert PPPoE from the router to PPPoA?

Try discussing this with Americans, and they can't quite understand PPPoA.

Cya
Simon

  #2  
Old May 21st 06, 03:15 PM posted to uk.telecom.broadband
Christopher
external usenet poster
 
Posts: 33
Default RFC1483 Bridged vs Bridged Mode Only


"Simon Dean" wrote in message
...
When connecting my ethernet modem to my smoothwall router/firewall, could
someone please explain, on the modem, what the difference is between
RFC1483 Bridged and Bridged Mode Only?

Which ones can be used in the UK?

You see, I keep coming back to the fact that in the UK, we're PPPoA, but
when you want to connect your modem to your router, you can't specify
PPPoA, it's RFC1483 Bridged, or Bridged Mode Only.

In Bridged Mode Only, we get to use PPPoE to authenticate from our router,
our Linux box, or our Windows XP, as suggested he
http://www.adslguide.org.uk/hardware...nksysADSL2.asp

So then presumably, rather than connecting by PPPoA, we go by PPPoE
because the computer takes control of the connection.

I've seen references for RFC 1483 - Multiprotocol Encapsulation over ATM.

So then I start to wonder, what does that mean? If we set up in RFC1483,
will the modem convert PPPoE from the router to PPPoA?

Try discussing this with Americans, and they can't quite understand PPPoA.

Cya
Simon


Simon - this from a forum

QUOTE

How can I tell if I am using PPPOE or RFC1483?

PPPOE - If your ISP assigned you a username and password; you are using
PPPOE

If your ISP assigned you a public static IP address, Subnet Mask, Default
Gateway and primary and secondary DNS addresses; you are using RFC1483.

Note: If you are not sure please contact your ISP.

UNQUOTE

hope it helps


  #3  
Old May 21st 06, 04:12 PM posted to uk.telecom.broadband
Moonshine
external usenet poster
 
Posts: 13
Default RFC1483 Bridged vs Bridged Mode Only

On Sun, 21 May 2006 15:15:50 +0100, "Christopher"
wrote:


"Simon Dean" wrote in message
...
When connecting my ethernet modem to my smoothwall router/firewall, could
someone please explain, on the modem, what the difference is between
RFC1483 Bridged and Bridged Mode Only?

Which ones can be used in the UK?

You see, I keep coming back to the fact that in the UK, we're PPPoA, but
when you want to connect your modem to your router, you can't specify
PPPoA, it's RFC1483 Bridged, or Bridged Mode Only.

In Bridged Mode Only, we get to use PPPoE to authenticate from our router,
our Linux box, or our Windows XP, as suggested he
http://www.adslguide.org.uk/hardware...nksysADSL2.asp

So then presumably, rather than connecting by PPPoA, we go by PPPoE
because the computer takes control of the connection.

I've seen references for RFC 1483 - Multiprotocol Encapsulation over ATM.

So then I start to wonder, what does that mean? If we set up in RFC1483,
will the modem convert PPPoE from the router to PPPoA?

Try discussing this with Americans, and they can't quite understand PPPoA.

Cya
Simon


Simon - this from a forum

QUOTE

How can I tell if I am using PPPOE or RFC1483?

PPPOE - If your ISP assigned you a username and password; you are using
PPPOE

If your ISP assigned you a public static IP address, Subnet Mask, Default
Gateway and primary and secondary DNS addresses; you are using RFC1483.

Note: If you are not sure please contact your ISP.

UNQUOTE

hope it helps



PPPoE is support in the UK by most ISP's - if you have an ethernet WAN
interfaced router that you want to connect to a DSL Modem so that it
gets the Public IP address you can configure the DSL Modem for
rfc1483 bridging and then configure your Router to use PPPoE (and
enter your DSL login details).
  #4  
Old May 21st 06, 05:07 PM posted to uk.telecom.broadband
Simon Dean
external usenet poster
 
Posts: 58
Default RFC1483 Bridged vs Bridged Mode Only

Moonshine wrote:


PPPoE is support in the UK by most ISP's - if you have an ethernet WAN
interfaced router that you want to connect to a DSL Modem so that it
gets the Public IP address you can configure the DSL Modem for
rfc1483 bridging and then configure your Router to use PPPoE (and
enter your DSL login details).


Hypothetically, assume ISP's only support PPPoA. Would Ethernet modems
still work in either the "RFC1483 Bridged" mode, or "Bridged Mode Only"?

I mean people still come out with stuff like "So as it supports RFC1483
(Bridge mode), you need to set it up in that mode to get it to work. In
bridge mode the modem acts as a protocol converter converting ethernet
into ADSL, this means that the host behind it has to handle all of the
login and IP stuff. "

Converts to ADSL? But is it PPPoA, or PPPoE? After the modem (if UK
ISP's did not support PPPoE), would it really matter? Is it PPPoE
because of the router?

Then there's things like "As far as Smoothwal [my router] is concerned,
there is no difference between PPPoA and PPPoE. It just cares about the
"PPP" (authentication) part, as the "oA" (over ATM) or "oE" (over
Ethernet) is an issue that needs to be handled by the modem/bridge to
which Smoothwall's RED interface is connected"

But then when you setup the modem in Bridged mode, you cannot specify
PPPoA, or PPPoE. So the choice of modes, oA or oE must surely be handled
by the router?

And, what's the difference between RFC1483 Bridged, and "Bridged Mode Only".

Cheers
Simon
  #5  
Old May 21st 06, 07:46 PM posted to uk.telecom.broadband
Bob
external usenet poster
 
Posts: 53
Default RFC1483 Bridged vs Bridged Mode Only

On Sun, 21 May 2006 18:07:35 +0100, Simon Dean wrote:

And, what's the difference between RFC1483 Bridged, and "Bridged Mode
Only".


I don't think that any UK ISP uses RFC1483 on ADSL, you want the other
one.



  #6  
Old May 21st 06, 07:59 PM posted to uk.telecom.broadband
Simon Dean
external usenet poster
 
Posts: 58
Default RFC1483 Bridged vs Bridged Mode Only

Moonshine wrote:


The best thing you can do is take a look at a diagram that shows the
various ADSL protocol stack implementations.

http://www2.rad.com/networks/2005/modems/ADSLprst.htm

Hopefully that way you can see where the various bits fit.

Bottom line is that in the UK at the user end PPP must be involved
somewhere for IP address allocation and end user authentication.

If you have 2 devices the functions can be split amongst them so long
as the right stack layering is used.


Yup. I get all that.

But in this instance, being in bridged mode, the choice of oA or oE is
decided by the device that does the authentication, in this case, the
router. The PPPoE that's setup in the router, won't get magically
changed by the modem to PPPoA, and it doesn't matter whether RFC1483 or
"Bridged Mode Only" do, they both just pass "PPPoE" across.

Bottom line, Is it physically impossible to have a bridged modem and a
PPPoA connection when the router only does PPPoA??? So if ISP's did not
support PPPoE, I would be stuffed unless I got an integrated router with
PPPoA, or some other router that could do PPPoA through the modem via
Ethernet....
  #7  
Old May 21st 06, 08:04 PM posted to uk.telecom.broadband
Simon Dean
external usenet poster
 
Posts: 58
Default RFC1483 Bridged vs Bridged Mode Only

Bob wrote:
On Sun, 21 May 2006 18:07:35 +0100, Simon Dean wrote:


And, what's the difference between RFC1483 Bridged, and "Bridged Mode
Only".



I don't think that any UK ISP uses RFC1483 on ADSL, you want the other
one.




That's what ADSLGuide suggest too. And all indications, as far as I can
tell, suggest that when the modem is put into Bridged Mode,
authentication passes to the router, or in my case smoothwall. Therefore
in my mind, my smoothwall establishes a PPPoE connection. So ergo (in my
mind) physically impossible to obtain a PPPoA connection when the modem
is bridged.

But that's what people suggest.

Which then begs the question, if ISP's didn't support PPPoE, I couldn't
have this setup, because it's physically impossible to do PPPoA (for
this setup)

ADSLGuide also say RFC1483 is irrelevent in the UK. Yet large numbers of
people suggest it. I also don't know what it is, or how it differs to
Bridged Mode Only, of which, there are no docs I can find.

Cya
Simon
  #8  
Old May 21st 06, 09:37 PM posted to uk.telecom.broadband
Bob
external usenet poster
 
Posts: 53
Default RFC1483 Bridged vs Bridged Mode Only

On Sun, 21 May 2006 21:04:14 +0100, Simon Dean wrote:

Bob wrote:
On Sun, 21 May 2006 18:07:35 +0100, Simon Dean wrote:


And, what's the difference between RFC1483 Bridged, and "Bridged Mode
Only".



I don't think that any UK ISP uses RFC1483 on ADSL, you want the other
one.




That's what ADSLGuide suggest too. And all indications, as far as I can
tell, suggest that when the modem is put into Bridged Mode,
authentication passes to the router, or in my case smoothwall. Therefore
in my mind, my smoothwall establishes a PPPoE connection. So ergo (in my
mind) physically impossible to obtain a PPPoA connection when the modem
is bridged.


It's really better to think of it as PPPoEoA

Which then begs the question, if ISP's didn't support PPPoE, I couldn't
have this setup, because it's physically impossible to do PPPoA (for
this setup)

ADSLGuide also say RFC1483 is irrelevent in the UK. Yet large numbers of
people suggest it. I also don't know what it is, or how it differs to
Bridged Mode Only, of which, there are no docs I can find.


IIRC RFC1483 is just an extra header that's slapped-on the front of the
AAL5 frame and doesn't do much except say: "this is ethernet", which isn't
much use unless there is the possibility it might be something else.

When I was recently looking for a modem, I looked into PPPoE and decided
against it. I just found so many problem reports about it. Some people say
that it wouldn't work until the ISP turned it on for them, someone said
Tiscali's support told him they didn't support it at all - but he still
got it to work. Lots of people complained that it's difficult to get
technical support on it, even from good ISPs, the frontline people often
just deny all knowledge of it. There is also the problem that it's only
widely supported because it's a BT feature, if you move to LLU, or you ISP
migrates to LLU, it may fail to work. There are also hassles with PPPoE
and mtu sizes.

I'm using FreeBSD so I went for an XModem, an Ethernet modem which
terminates PPPoA itself and hands over the public address by DHCP. For
Linux I'd probably go with an internal PCI modem. I think these are both
better solutions.

  #9  
Old May 21st 06, 10:34 PM posted to uk.telecom.broadband
Graham Murray
external usenet poster
 
Posts: 207
Default RFC1483 Bridged vs Bridged Mode Only

Bob writes:

There is also the problem that it's only widely supported because
it's a BT feature, if you move to LLU, or you ISP migrates to LLU,
it may fail to work. There are also hassles with PPPoE and mtu
sizes.


Yet I believe that almost everywhere else in the world ADSL is
provided using PPPoE not PPPoA. So there should be lots of support etc
available on the web.
  #10  
Old May 22nd 06, 12:21 AM posted to uk.telecom.broadband
Bob
external usenet poster
 
Posts: 53
Default RFC1483 Bridged vs Bridged Mode Only

On Sun, 21 May 2006 23:19:45 +0100, Simon Dean wrote:

Bob wrote:
On Sun, 21 May 2006 21:04:14 +0100, Simon Dean wrote:


Bob wrote:

On Sun, 21 May 2006 18:07:35 +0100, Simon Dean wrote:



And, what's the difference between RFC1483 Bridged, and "Bridged
Mode Only".


I don't think that any UK ISP uses RFC1483 on ADSL, you want the
other one.





That's what ADSLGuide suggest too. And all indications, as far as I
can tell, suggest that when the modem is put into Bridged Mode,
authentication passes to the router, or in my case smoothwall.
Therefore in my mind, my smoothwall establishes a PPPoE connection. So
ergo (in my mind) physically impossible to obtain a PPPoA connection
when the modem is bridged.



It's really better to think of it as PPPoEoA


PPPoE, over the ATM network?

Which then begs the question, if ISP's didn't support PPPoE, I
couldn't have this setup, because it's physically impossible to do
PPPoA (for this setup)

ADSLGuide also say RFC1483 is irrelevent in the UK. Yet large numbers
of people suggest it. I also don't know what it is, or how it differs
to Bridged Mode Only, of which, there are no docs I can find.


IIRC RFC1483 is just an extra header that's slapped-on the front of the
AAL5 frame and doesn't do much except say: "this is ethernet", which
isn't much use unless there is the possibility it might be something
else.


That explains why it's not much use in the UK then I guess.


When I was recently looking for a modem, I looked into PPPoE and
decided against it. I just found so many problem reports about it. Some
people say that it wouldn't work until the ISP turned it on for them,
someone said Tiscali's support told him they didn't support it at all -
but he still got it to work. Lots of people complained that it's
difficult to get technical support on it, even from good ISPs, the
frontline people often just deny all knowledge of it. There is also the
problem that it's only widely supported because it's a BT feature, if
you move to LLU, or you ISP migrates to LLU, it may fail to work. There
are also hassles with PPPoE and mtu sizes.


Bringing me back to one of the original questions... with the modem in
bridged mode, it functions just like a modem, so I would need my Linux
box to do PPPoA authentication.


Yes

I personally found setting it up rather easy. It's just trying to figure
which bit of it decides on PPPoE or PPPoA and what the different
bridging modes are. As I say, there's some people that say that PPPoE or
PPPoA is decided and handled in the modem, which sounds like balls
because once you set the bridging mode, you don't specify whether you
wana oA or oE so I assert that's handled on the router itself. Why do
things have to be so difficult. then they say "it really doesn't matter
as long as the PPP bit is done". Then why do we have different modes?


You have to run PPP over something. In the US they use mostly ethernet, in
Europe it's mostly ATM. BT added a hybrid version where ppp runs over
ethernet, which in turn runs over their ATM network.

I'm using FreeBSD so I went for an XModem, an Ethernet modem which
terminates PPPoA itself and hands over the public address by DHCP. For
Linux I'd probably go with an internal PCI modem. I think these are
both better solutions.


Ahh. That would be an infamous half bridge solution of sorts? You got a
link for the XModem?


adslnation.co.uk , but there are other similar products

the less things I stick inside the box the better. I don't trust things
like the USB support, and PCI on Linux. sounds like it's asking for
trouble trying to find the right devices that work. But it's always a
possibility.



Bear in mind that the majority of ADSL routers are based on Linux.


 




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