Let's say that your ISP is company A. Then the packets leaving your router pass through servers belonging to A. At some point you change your ISP to company B. Then the packets will go through the servers belonging to B.
For xDSL networks, your packets reach routers operated by A or B,
because your router authenticates and creates a PPP tunnel to A or B,
all traffic then travels through the tunnel.
Spiros Bousbouras wrote:
Let's say that your ISP is company A. Then the packets leaving your router pass through servers belonging to A. At some point you change your ISP to company B. Then the packets will go through the servers belonging to B.
For xDSL networks, your packets reach routers operated by A or B,
because your router authenticates and creates a PPP tunnel to A or B,
all traffic then travels through the tunnel.
On Sun, 25 Jul 2021 10:52:07 +0100
Andy Burns <usenet@andyburns.uk> wrote:
Spiros Bousbouras wrote:
Let's say that your ISP is company A. Then the packets leaving your router >>> pass through servers belonging to A. At some point you change your ISP to >>> company B. Then the packets will go through the servers belonging to B.
For xDSL networks, your packets reach routers operated by A or B,
because your router authenticates and creates a PPP tunnel to A or B,
all traffic then travels through the tunnel.
How does my router know whether to communicate with the routers of A or B ? How does it know their IP addresses for example ?
Regarding authentication , how does it know the right credentials ? For example en.wikipedia.org/wiki/Challenge-Handshake_Authentication_Protocol says
CHAP requires that both the client and server know the plaintext of the
secret, although it is never sent over the network.
So I guess that my router and the router of the ISP must know some common secret. How does this get established ?
On Sun, 25 Jul 2021 10:52:07 +0100
Andy Burns <usenet@andyburns.uk> wrote:
Spiros Bousbouras wrote:
Let's say that your ISP is company A. Then the packets leaving
your router pass through servers belonging to A. At some point
you change your ISP to company B. Then the packets will go
through the servers belonging to B.
For xDSL networks, your packets reach routers operated by A or B,
because your router authenticates and creates a PPP tunnel to A or
B, all traffic then travels through the tunnel.
How does my router know whether to communicate with the routers of A
or B ? How does it know their IP addresses for example ?
Spiros Bousbouras <spibou@gmail.com> wrote:
On Sun, 25 Jul 2021 10:52:07 +0100
Andy Burns <usenet@andyburns.uk> wrote:
For xDSL networks, your packets reach routers operated by A or B,
because your router authenticates and creates a PPP tunnel to A or
B, all traffic then travels through the tunnel.
How does my router know whether to communicate with the routers of A
or B ? How does it know their IP addresses for example ?
You tell it via the "default route" you setup when you configure it.
Let's say that your ISP is company A. Then the packets leaving your
router pass through servers belonging to A. At some point you change
your ISP to company B. Then the packets will go through the servers
belonging to B.
Which device(s) decide where to send the packets leaving your router
and how does it/they know to which provider to send them ?
I understand that there are probably many different set ups , I'm
just asking for an idea how it might work.
For ADSL the wiring will need to be changed in the exchange (aka central office) to connect you to company B's equipment, for VDSL it's usually a logical change, by the line provider to let you reach company B, rather
than a physical wiring change.
Spiros Bousbouras wrote:
On Sun, 25 Jul 2021 10:52:07 +0100
Andy Burns <usenet@andyburns.uk> wrote:
For xDSL networks, your packets reach routers operated by A or B,
because your router authenticates and creates a PPP tunnel to A or B,
all traffic then travels through the tunnel.
How does my router know whether to communicate with the routers of A or B ? How does it know their IP addresses for example ?
depends, you're not giving many clues in terms of which continent you're
on, or what connection type you have, these things do vary a bit.
If it's ADSL, your router hasn't got much choice, the wires from your
house lead straight to the equipment (DSLAM) for your ISP
Regarding authentication , how does it know the right credentials ? For example en.wikipedia.org/wiki/Challenge-Handshake_Authentication_Protocol says
CHAP requires that both the client and server know the plaintext of the
secret, although it is never sent over the network.
In this country, only BT doesn't require authentication, because they
know which phone line you're on and use that instead
I'm asking for my general education so any reply for any location
and any set up would be interesting to me.
So if it's an xDSL network then it is physically possible for the
packets to travel from any home router to several ISPs.
Who owns the routers which decide which ISP the packets go to ? Is
it BT ?
On 7/25/21 3:42 AM, Spiros Bousbouras wrote:
Let's say that your ISP is company A. Then the packets leaving your
router pass through servers belonging to A. At some point you change
your ISP to company B. Then the packets will go through the servers belonging to B.
Please clarify the timing that you're talking about when you say "at
some point". Are you referring to a one time change - say ISP B is new
and offers a sale to get you to switch to them,
or are you referring to
some special connection that uses both ISP A and ISP B /concurrently/ (depending on various configurations)?
If it's ADSL, your router hasn't got much choice, the wires from your
house lead straight to the equipment (DSLAM) for your ISP
In this country, only BT doesn't require authentication, because they
know which phone line you're on and use that instead
all other ISPs either require you to put a username and password in the router, or they pre-configure it before they send the router out to you,
or use an automatic configuration system TR-069 which uses an identifier (e.g. serial number) of the router to setup the parameters for you.
On 7/25/21 8:31 AM, Andy Burns wrote:
If it's ADSL, your router hasn't got much choice, the wires from your
house lead straight to the equipment (DSLAM) for your ISP
ADSL in particular, and xDSL in general as I understand it, supports
common DSLAMs. (See my reply a few minutes ago for more details.)
ATM based DSL supports multiple PVCs across the single physical
connection.
-- This would be called a Service Access Loop in ATM
parlance. -- Thus ATM based DSL /technically/ /supports/ concurrent connections to multiple ISPs through the use of different PVCs.
I have used ATM DSL modems that supported up to eight different PVCs. As
in the modem itself established the PVC using the PVI and SVI provided
by the router.
In this country, only BT doesn't require authentication, because they
know which phone line you're on and use that instead
That's because there is association with the physical port on the DSLAM
with the phone line that is connected. This pre-defined circuit makes
it from the DSLAM through the provider's telco network to the router on
the far side. The router has different logical interfaces that
represent the physical DSLAM port. So there is a one-for-one mapping.
As long as the association / mapping is maintained properly, you can
easily know that logical port XYZ123 is phone number ABC-9876.
all other ISPs either require you to put a username and password in
the router, or they pre-configure it before they send the router out
to you,
That may be the case where you are. But where I'm from, all three of
the ADSL ISPs (1 x ILEC and 2 x independent) used the one-for-one
mapping described above.
The PPPoE / DHCP / static configuration is
actually (bridged / encapsulated) Ethernet frame riding across the DSL network -- which is more akin to point-to-point logical Ethernet links
in this regard -- to the ISP who provides the counterpart for PPPoE /
DHCP / static configuration.
or use an automatic configuration system TR-069 which uses an
identifier (e.g. serial number) of the router to setup the parameters
for you.
Things started with DHCP & static configuration and then progressed to
PPPoE where I'm from.
The PPPoE enabled providers to care less (or not
at all) about the one-for-one mapping described above and instead rely
on PPPoE's authentication capabilities. Thus the DSL became even more
of a point-to-point Ethernet LAN. Or, more accurately point (ISP) to multi-point (DSL subscribers) as subscriber to subscriber still needed
to pass through the ISP's head end, for both layer 2 and layer 3.
For ADSL smaller ISPs here likely use BT's DSLAMs, larger ISPs have
provided their own, that's changing as more move to VDSL and use common
MSANs where the fibre backhaul reaches the street cabinet.
But do any providers make use of that? Technically it's possible but
here it's never used.
It might have been nice to provision a home ISP and a work ISP on
the same line using different VCI/VPI numbers,
most providers used the same VCI/VPI nunbers,
I can only think of one that even used different numbers, then decide
on a split of bandwidth for each, but in practice most home ADSL
users want more bandwidth than is available, so you either end up
using home's bandwidht for work, or having a separate line.
But do they *use* that where you are either?
Yep, but the only ISP that uses that here is the one who is BT, the
owner of the kit in the exchanges (ok there's an arm's length separation between BT Openreach who own the kit and the wires, and BT Internet who
are the ISP)
I'm sure it varies around the planet, here ADSL uses ATM and PPPoE, VDSL
uses PPPoE
PPoE still uses authentication here.
Where "this country" means the U.K. So if it's an xDSL network then it is >physically possible for the packets to travel from any home router to several >ISPs. Who owns the routers which decide which ISP the packets go to ? Is
it BT ?
Where I'm from there is a lot of rural area where a single DSLAM may
have trouble covering line length to connect to 32 houses. So 8 and 16
port DSLAMs were common. In such sparse areas, each ISP deploying their
own DSLAM would be *EXTREMELY* inefficient if not wasteful.
I did my best to avoid PPPoE because of the complications related to MTU
/ MSS.
Grant Taylor <gtaylor@tnetconsulting.net> wrote:
Where I'm from there is a lot of rural area where a single DSLAM may
have trouble covering line length to connect to 32 houses. So 8 and 16 >port DSLAMs were common. In such sparse areas, each ISP deploying their >own DSLAM would be *EXTREMELY* inefficient if not wasteful.
Where I am, we have low population density, but only one DSL provider,
namely the telco that owns the local loops. So that's who owns the
DSLAM and when you get out onto the vast and dizzying internet, you are
doing so from an IP address owned by them. This is typical of much of
rural America.
You tell it via the "default route" you setup when you configure it.
I never did any such configuring on my current router. But , since it was provided by my ISP , it probably came preconfigured.
But this leads to another question : what if someone enters a route
not for an ISP they are subscribing to ?
I never did any such configuring on my current router. But , since
it was provided by my ISP , it probably came preconfigured.
But this leads to another question : what if someone enters
a route not for an ISP they are subscribing to ?
I'm guessing that some authentication will fail but if they somehow
manage to crack the authentication process then they can get internet
access without paying an ISP , right ?
I was reading earlier en.wikipedia.org/wiki/TR-069
and they say that routers are crackable.
The setting is different but if an outsider can crack a router then
I'm guessing that the owner can too.
DHCP's not the only option, PPP is also used apparently since others mentioned it.
My country implemented ADSL usually with RFC1483 where ethernet
packets are stuffed into ATM cells. Awful for efficiency, about 15%
wasted on framing total (TCP+IP+Ethernet+ATM headers). Although I
assume PPP doesn't help with that much.
Your router only talks to the ISP's router ....
Routers route what they're configured to route where they are
configured to route it. And if no route exist, well, your bits aren't
going to go anywhere.
There are other was to put IP, and likely PPP(oE) on ATM, but they are
seldom done as (over) Ethernet has become the defacto standard.
Your router only talks to the ISP's router ....
Likely not even that.
The OPs router will send frames into the ether looking for the router
it's configured to talk to. It will extremely likely be unable to
find said router, thus won't talk to any router.
I'm asking for my general education so any reply for any location and any
set up would be interesting to me.
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