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PAP , CHAP AND HOW AT&T WORKS 13 years 1 month ago #13093

1) what is the difference between PAP and CHAP
2) what is the difference between ppp over ethernet and ppp over atm
3) I work for AT&T I know something about the internal working of an ISP but I don't have the complete knowledge about how these things work
all that I know is :-
a) data comes from atm cloud to the central office/Remote terminal
b) atm signals are directed towards redback routers
c) from redback routers these signals enter a big atm switch
d) from this switch some of the signals go into the radius server through an L2TP tunnel and some of the signals go into the core dsl through tcp/ip. These signals are then forwarded to the Ldap through L2TP tunnel
e) also from the at&t network some signals go into the core (main) through tcp/ip from where again these signals are forwarded to the core dsl
f) from the core dsl some of these signals are forwarded to the SRVR form where these signals are forwarded to the dns and the secure server
g) and some signals are forwarded from the core dsl to the edge router
h) from the edge router the signals are forwarded to the backbone provider edge router through tcp/ip
i) from the backbone router the signals are forwarded to the internet

now these steps can can move from the internet to the atm cloud that is in the reverse order completely as well

Now I don't know all the devices involved in this process and as well as their individual functions
Pls give me a detailed description of the things and the technology involved so that I can work in AT&T with complete knowledge
In God we trust but for everything else we need data

Re: PAP , CHAP AND HOW AT&T WORKS 13 years 1 month ago #13094

seems like in the at&t network the data flow is a complete spaghetty!

the basic difference between pap and chap is that with pap you send your password in clear text and is a one way step process.
with chap, you dont send the password, instead the aaa servers or device sends a challenge packet, the client then sends the responde of the challenge, bute the passwords are never send over the media, so it is a superior option over pap.

of course in both cases the same username and passwords must match in both devices the client, and the server.

Re: PAP , CHAP AND HOW AT&T WORKS 13 years 1 month ago #13095

Links below should provide you with enough information to read and hopefully answer your questions. [PPP CHAP] [PPP PAP CHAP] [PPP Over Ethernet] [PPP Over Ethernet] [PPP Over ATM] [IETF-Compliant PPP Over ATM]
<= IИse©u®ity Is A ®esult Of T®ying To Be Se©u®e =>

.....guess work... 13 years 1 month ago #13256

Hi All,

The description of the network given is plausible and shows a picture is definately worth a lot of words. Here is what I think is going on:

Part 1 Customer Access to DSL network

[PC] <--Eth/USB--> [CPE/MODE] <---ATM over DSL

Part 2 DSLAM & access to core network (continues from above)

---> [DSLAM] <---(ATM Cloud)---> [BRAS (Redback)] <---

Part 3 Customer authentication

[Radius Server]
Fast Ethernet Link
using L2TP
[BRAS (Redback)]

Part 4 Access to IP Cloud (continue from part 2)

--Fast Ethernet / IP --> (IP CLOUD)<----> [Edge Router] <---> Internet

I'd expect the DNS & Secure servers to be connected to the IP Cloud.

The ATM switch would be part of the ATM cloud.

I hope this helps. Ask more questions and read the RFCs as recommended by Dead-NeurOns.


Patience - the last reserve of the any engineer
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