msgid "" msgstr "" "Project-Id-Version: English (cnp3-ebook)\n" "Report-Msgid-Bugs-To: \n" "POT-Creation-Date: 2026-04-18 17:29+0200\n" "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n" "Last-Translator: FULL NAME \n" "Language-Team: English \n" "Language: en\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n" "Plural-Forms: nplurals=2; plural=n != 1;\n" "X-Generator: Weblate 5.14.3\n" #: ../../protocols/ppp.rst:7 #, read-only msgid "The Point-to-Point Protocol" msgstr "The Point-to-Point Protocol" #: ../../protocols/ppp.rst:9 #, read-only msgid "" "Many point-to-point datalink layers [#flapb]_ have been developed, starting " "in the 1960s. In this section, we focus on the protocols that are often used " "to transport IP packets between hosts or routers that are directly connected " "by a point-to-point link. This link can be a dedicated physical cable, a " "leased line through the telephone network or a dial-up connection with " "modems on the two communicating hosts." msgstr "" "Many point-to-point datalink layers [#flapb]_ have been developed, starting " "in the 1960s. In this section, we focus on the protocols that are often used " "to transport IP packets between hosts or routers that are directly connected " "by a point-to-point link. This link can be a dedicated physical cable, a " "leased line through the telephone network or a dial-up connection with " "modems on the two communicating hosts." #: ../../protocols/ppp.rst:13 #, read-only msgid "" "The first solution to transport IP packets over a serial line was proposed " "in :rfc:`1055` and is known as `Serial Line IP` (SLIP). SLIP is a simple " "character stuffing technique applied to IP packets. SLIP defines two special " "characters : `END` (decimal 192) and `ESC` (decimal 219). `END` appears at " "the beginning and at the end of each transmitted IP packet and the sender " "adds `ESC` before each `END` character inside each transmitted IP packet. " "SLIP only supports the transmission of IP packets and it assumes that the " "two communicating hosts/routers have been manually configured with each " "other's IP address. SLIP was mainly used over links offering bandwidth of " "often less than 20 Kbps. On such a low bandwidth link, sending 20 bytes of " "IP header followed by 20 bytes of TCP header for each TCP segment takes a " "lot of time. This initiated the development of a family of compression " "techniques to efficiently compress the TCP/IP headers. The first header " "compression technique proposed in :rfc:`1144` was designed to exploit the " "redundancy between several consecutive segments that belong to the same TCP " "connection. In all these segments, the IP addresses and port numbers are " "always the same. Furthermore, fields such as the sequence and acknowledgment " "numbers do not change in a random way. :rfc:`1144` defined simple techniques " "to reduce the redundancy found in successive segments. The development of " "header compression techniques continued and there are still improvements " "being developed now :rfc:`5795`." msgstr "" "The first solution to transport IP packets over a serial line was proposed " "in :rfc:`1055` and is known as `Serial Line IP` (SLIP). SLIP is a simple " "character stuffing technique applied to IP packets. SLIP defines two special " "characters : `END` (decimal 192) and `ESC` (decimal 219). `END` appears at " "the beginning and at the end of each transmitted IP packet and the sender " "adds `ESC` before each `END` character inside each transmitted IP packet. " "SLIP only supports the transmission of IP packets and it assumes that the " "two communicating hosts/routers have been manually configured with each " "other's IP address. SLIP was mainly used over links offering bandwidth of " "often less than 20 Kbps. On such a low bandwidth link, sending 20 bytes of " "IP header followed by 20 bytes of TCP header for each TCP segment takes a " "lot of time. This initiated the development of a family of compression " "techniques to efficiently compress the TCP/IP headers. The first header " "compression technique proposed in :rfc:`1144` was designed to exploit the " "redundancy between several consecutive segments that belong to the same TCP " "connection. In all these segments, the IP addresses and port numbers are " "always the same. Furthermore, fields such as the sequence and acknowledgment " "numbers do not change in a random way. :rfc:`1144` defined simple techniques " "to reduce the redundancy found in successive segments. The development of " "header compression techniques continued and there are still improvements " "being developed now :rfc:`5795`." #: ../../protocols/ppp.rst:15 #, read-only msgid "" "While SLIP was implemented and used in some environments, it had several " "limitations discussed in :rfc:`1055`. The `Point-to-Point Protocol` (PPP) " "was designed shortly after and is specified in :rfc:`1548`. PPP aims to " "support IP and other network layer protocols over various types of serial " "lines. PPP is in fact a family of three protocols that are used together :" msgstr "" "While SLIP was implemented and used in some environments, it had several " "limitations discussed in :rfc:`1055`. The `Point-to-Point Protocol` (PPP) " "was designed shortly after and is specified in :rfc:`1548`. PPP aims to " "support IP and other network layer protocols over various types of serial " "lines. PPP is in fact a family of three protocols that are used together :" #: ../../protocols/ppp.rst:17 #, read-only msgid "" "The `Point-to-Point Protocol` defines the framing technique to transport " "network layer packets." msgstr "" "The `Point-to-Point Protocol` defines the framing technique to transport " "network layer packets." #: ../../protocols/ppp.rst:18 #, read-only msgid "" "The `Link Control Protocol` that is used to negotiate options and " "authenticate the session by using username and password or other types of " "credentials" msgstr "" "The `Link Control Protocol` that is used to negotiate options and " "authenticate the session by using username and password or other types of " "credentials" #: ../../protocols/ppp.rst:19 #, read-only msgid "" "The `Network Control Protocol` that is specific for each network layer " "protocol. It is used to negotiate options that are specific for each " "protocol. For example, IPv4's NCP :rfc:`1548` can negotiate the IPv4 address " "to be used, the IPv4 address of the DNS resolver. IPv6's NCP is defined in " ":rfc:`5072`." msgstr "" "The `Network Control Protocol` that is specific for each network layer " "protocol. It is used to negotiate options that are specific for each " "protocol. For example, IPv4's NCP :rfc:`1548` can negotiate the IPv4 address " "to be used, the IPv4 address of the DNS resolver. IPv6's NCP is defined in " ":rfc:`5072`." #: ../../protocols/ppp.rst:21 #, read-only msgid "" "The PPP framing :rfc:`1662` was inspired by the datalink layer protocols " "standardized by ITU-T and ISO. A typical PPP frame is composed of the fields " "shown in the figure below. A PPP frame starts with a one byte flag " "containing `01111110`. PPP can use bit stuffing or character stuffing " "depending on the environment where the protocol is used. The address and " "control fields are present for backward compatibility reasons. The 16 bit " "Protocol field contains the identifier [#fpppid]_ of the network layer " "protocol that is carried in the PPP frame. `0x002d` is used for an IPv4 " "packet compressed with :rfc:`1144` while `0x002f` is used for an " "uncompressed IPv4 packet. `0xc021` is used by the Link Control Protocol, " "`0xc023` is used by the Password Authentication Protocol (PAP). `0x0057` is " "used for IPv6 packets. PPP supports variable length packets, but LCP can " "negotiate a maximum packet length. The PPP frame ends with a Frame Check " "Sequence. The default is a 16 bits CRC, but some implementations can " "negotiate a 32 bits CRC. The frame ends with the `01111110` flag." msgstr "" "The PPP framing :rfc:`1662` was inspired by the datalink layer protocols " "standardized by ITU-T and ISO. A typical PPP frame is composed of the fields " "shown in the figure below. A PPP frame starts with a one byte flag " "containing `01111110`. PPP can use bit stuffing or character stuffing " "depending on the environment where the protocol is used. The address and " "control fields are present for backward compatibility reasons. The 16 bit " "Protocol field contains the identifier [#fpppid]_ of the network layer " "protocol that is carried in the PPP frame. `0x002d` is used for an IPv4 " "packet compressed with :rfc:`1144` while `0x002f` is used for an " "uncompressed IPv4 packet. `0xc021` is used by the Link Control Protocol, " "`0xc023` is used by the Password Authentication Protocol (PAP). `0x0057` is " "used for IPv6 packets. PPP supports variable length packets, but LCP can " "negotiate a maximum packet length. The PPP frame ends with a Frame Check " "Sequence. The default is a 16 bits CRC, but some implementations can " "negotiate a 32 bits CRC. The frame ends with the `01111110` flag." #: ../../protocols/ppp.rst:27 #, read-only msgid "PPP frame format" msgstr "PPP frame format" #: ../../protocols/ppp.rst:31 #, read-only msgid "" "PPP played a key role in allowing Internet Service Providers to provide dial-" "up access over modems in the late 1990s and early 2000s. ISPs operated modem " "banks connected to the telephone network. For these ISPs, a key issue was to " "authenticate each user connected through the telephone network. This " "authentication was performed by using the `Extensible Authentication " "Protocol` (EAP) defined in :rfc:`3748`. EAP is a simple, but extensible " "protocol that was initially used by access routers to authenticate the users " "connected through dial-up lines. Several authentication methods, starting " "from the simple username/password pairs to more complex schemes have been " "defined and implemented. When ISPs started to upgrade their physical " "infrastructure to provide Internet access over `Asymmetric Digital " "Subscriber Lines` (ADSL), they tried to reuse their existing authentication " "(and billing) systems. To meet these requirements, the IETF developed " "specifications to allow PPP frames to be transported over other networks " "than the point-to-point links for which PPP was designed. Nowadays, most " "ADSL deployments use PPP over either ATM :rfc:`2364` or Ethernet :rfc:`2516`." msgstr "" "PPP played a key role in allowing Internet Service Providers to provide dial-" "up access over modems in the late 1990s and early 2000s. ISPs operated modem " "banks connected to the telephone network. For these ISPs, a key issue was to " "authenticate each user connected through the telephone network. This " "authentication was performed by using the `Extensible Authentication " "Protocol` (EAP) defined in :rfc:`3748`. EAP is a simple, but extensible " "protocol that was initially used by access routers to authenticate the users " "connected through dial-up lines. Several authentication methods, starting " "from the simple username/password pairs to more complex schemes have been " "defined and implemented. When ISPs started to upgrade their physical " "infrastructure to provide Internet access over `Asymmetric Digital " "Subscriber Lines` (ADSL), they tried to reuse their existing authentication " "(and billing) systems. To meet these requirements, the IETF developed " "specifications to allow PPP frames to be transported over other networks " "than the point-to-point links for which PPP was designed. Nowadays, most " "ADSL deployments use PPP over either ATM :rfc:`2364` or Ethernet :rfc:`2516`." #: ../../protocols/ppp.rst:34 #, read-only msgid "Footnotes" msgstr "Footnotes" #: ../../protocols/ppp.rst:35 #, read-only msgid "" "`LAPB `_ and `HDLC `_ were widely used datalink layer protocols." msgstr "" "`LAPB `_ and `HDLC `_ were widely used datalink layer protocols." #: ../../protocols/ppp.rst:37 #, read-only msgid "" "The IANA maintains the registry of all assigned PPP protocol fields at : " "http://www.iana.org/assignments/ppp-numbers" msgstr "" "The IANA maintains the registry of all assigned PPP protocol fields at : " "http://www.iana.org/assignments/ppp-numbers"