Point-to-Point Protocol over ATM: Difference between revisions
imported>NOTAROBOT1101 m Expand some acronyms, add some links, use proper dashes |
imported>Kvng match title. MOS:NOTSEEALSO. WP:DUPLINK. |
||
| Line 1: | Line 1: | ||
{{Short description|Computer network protocol}} | {{Short description|Computer network protocol}} | ||
In [[computer networking]], the '''[[Point-to-Point Protocol]] over [[Asynchronous Transfer Mode]]''' ('''PPPoA''') is a [[OSI model|layer 2]] data-link protocol typically used to connect domestic broadband [[Modem|modems]] to [[Internet service provider|ISPs]] via phone lines. It is used mainly with [[DOCSIS]] and [[Digital subscriber line|DSL]] carriers, by [[Encapsulation (networking)|encapsulating]] Point-to-Point Protocol (PPP) frames in ATM [[AAL5]]. PPPoA is specified by the [[Internet Engineering Task Force|Internet Engineering Task Force (IETF)]] in RFC 2364.<ref name=RFC2364>{{cite journal|title=RFC 2364, PPP over AAL5|year=1998|url=http://tools.ietf.org/html/rfc2364|accessdate=2013-04-15|publisher=IETF|ref=rfc:2364 |last1=Malis |first1=Anew G. |last2=Lin |first2=Arthur Y. |last3=Stephens |first3=John |last4=Gross |first4=George |last5=Kaycee |first5=Manu }}</ref> | |||
In [[computer networking]], the '''[[Point-to-Point Protocol]] over [[Asynchronous Transfer Mode|ATM]]''' ('''PPPoA''') is a [[OSI model|layer 2]] data-link protocol typically used to connect domestic broadband [[Modem|modems]] to [[Internet service provider|ISPs]] via phone lines. It is used mainly with [[DOCSIS]] and [[Digital subscriber line|DSL]] carriers, by [[Encapsulation (networking)|encapsulating]] Point-to-Point Protocol (PPP) frames in ATM [[AAL5]]. PPPoA is specified by the [[Internet Engineering Task Force|Internet Engineering Task Force (IETF)]] in RFC 2364.<ref name=RFC2364>{{cite journal|title=RFC 2364, PPP over AAL5|year=1998|url=http://tools.ietf.org/html/rfc2364|accessdate=2013-04-15|publisher=IETF|ref=rfc:2364 |last1=Malis |first1=Anew G. |last2=Lin |first2=Arthur Y. |last3=Stephens |first3=John |last4=Gross |first4=George |last5=Kaycee |first5=Manu }}</ref> | |||
It offers standard [[Point-to-point protocol|PPP]] features such as [[authentication]], [[encryption]], and [[Data compression|compression]]. It also supports the encapsulation types: [[VC-MUX]] and [[Logical Link Control|LLC]] — see [https://tools.ietf.org/html/rfc2364 RFC 2364]. | It offers standard [[Point-to-point protocol|PPP]] features such as [[authentication]], [[encryption]], and [[Data compression|compression]]. It also supports the encapsulation types: [[VC-MUX]] and [[Logical Link Control|LLC]] — see [https://tools.ietf.org/html/rfc2364 RFC 2364]. | ||
If it is used as the connection encapsulation method on an ATM based network it can reduce overhead significantly compared with [[Point-to-Point Protocol over Ethernet|PPPoEoA]] — by between 0 and ~3.125% for long packets, depending on the packet length and also on the choices of header options in PPPoEoA — see [[Point-to-Point Protocol over Ethernet#Use with DSL – PPPoE over ATM (PPPoEoA)|PPPoEoA protocol overheads]]. This is because it uses headers that are short so imposes minimal overheads, 2 bytes for PPP and 8 bytes for PPPoA (with the RFC2364 VC-MUX option) = '''10 bytes'''.<ref>Dirk Van Aken, Sascha Peckelbeen [http://wand.cs.waikato.ac.nz/~513/2006/readings/adsl-2.pdf Encapsulation Overhead(s) in ADSL Access Networks], June 2003</ref><ref>[https://tools.ietf.org/html/rfc2364 RFC 2364]</ref><ref>[https://tools.ietf.org/html/rfc2684 RFC 2684]</ref> | If it is used as the connection encapsulation method on an ATM based network, it can reduce overhead significantly compared with [[Point-to-Point Protocol over Ethernet|PPPoEoA]] — by between 0 and ~3.125% for long packets, depending on the packet length and also on the choices of header options in PPPoEoA — see [[Point-to-Point Protocol over Ethernet#Use with DSL – PPPoE over ATM (PPPoEoA)|PPPoEoA protocol overheads]]. This is because it uses headers that are short so imposes minimal overheads, 2 bytes for PPP and 8 bytes for PPPoA (with the RFC2364 VC-MUX option) = '''10 bytes'''.<ref>Dirk Van Aken, Sascha Peckelbeen [http://wand.cs.waikato.ac.nz/~513/2006/readings/adsl-2.pdf Encapsulation Overhead(s) in ADSL Access Networks], June 2003</ref><ref>[https://tools.ietf.org/html/rfc2364 RFC 2364]</ref><ref>[https://tools.ietf.org/html/rfc2684 RFC 2684]</ref> | ||
It also avoids the issues that PPPoE suffers from, related to sometimes needing to use an IP [[MTU (networking)|MTU]] of 1492 bytes or less, lower than the standard 1500 bytes. | It also avoids the issues that PPPoE suffers from, related to sometimes needing to use an IP [[MTU (networking)|MTU]] of 1492 bytes or less, lower than the standard 1500 bytes. | ||
| Line 21: | Line 22: | ||
* Multiplexing (Method): such as [[VC-MUX]] or [[Logical Link Control|LLC]] | * Multiplexing (Method): such as [[VC-MUX]] or [[Logical Link Control|LLC]] | ||
ATM configuration can either be performed manually, or it may be hard-coded (or pre-set) into the [[firmware]] of a | ATM configuration can either be performed manually, or it may be hard-coded (or pre-set) into the [[firmware]] of a DSL modem provided by the user's ISP; it cannot be automatically negotiated. | ||
==See also== | ==See also== | ||
*[[PPPoX]] | *[[PPPoX]] | ||
*[[L2TP]] | *[[L2TP]] | ||
== Notes == | == Notes == | ||
Latest revision as of 14:00, 22 June 2025
In computer networking, the Point-to-Point Protocol over ATM (PPPoA) is a layer 2 data-link protocol typically used to connect domestic broadband modems to ISPs via phone lines. It is used mainly with DOCSIS and DSL carriers, by encapsulating Point-to-Point Protocol (PPP) frames in ATM AAL5. PPPoA is specified by the Internet Engineering Task Force (IETF) in RFC 2364.[1]
It offers standard PPP features such as authentication, encryption, and compression. It also supports the encapsulation types: VC-MUX and LLC — see RFC 2364.
If it is used as the connection encapsulation method on an ATM based network, it can reduce overhead significantly compared with PPPoEoA — by between 0 and ~3.125% for long packets, depending on the packet length and also on the choices of header options in PPPoEoA — see PPPoEoA protocol overheads. This is because it uses headers that are short so imposes minimal overheads, 2 bytes for PPP and 8 bytes for PPPoA (with the RFC2364 VC-MUX option) = 10 bytes.[2][3][4]
It also avoids the issues that PPPoE suffers from, related to sometimes needing to use an IP MTU of 1492 bytes or less, lower than the standard 1500 bytes.
The use of PPPoA over PPPoE is not geographically significant; rather, it varies by the provider's preference.
Configuration
Configuration of a PPPoA requires PPP configuration and ATM configuration. These data are generally stored in a cable modem or DSL modem, and may or may not be visible to—or configurable by—an end-user.
PPP configuration generally includes: user credentials, user name and password, and is unique to each user.
ATM configuration includes:
- Virtual channel link (VCL) – virtual path identifier and virtual channel identifier (VPI/VCI), such as 0/32 (analogous to a phone number)
- Modulation (Type): such as G.dmt
- Multiplexing (Method): such as VC-MUX or LLC
ATM configuration can either be performed manually, or it may be hard-coded (or pre-set) into the firmware of a DSL modem provided by the user's ISP; it cannot be automatically negotiated.
See also
Notes
External links
- A typical PPPoA architecture diagram (out of date and no longer maintained)