Pseudo-wire
From Wikipedia, the free encyclopedia
In computer networking and telecommunications, a pseudowire (PW) is an emulation of a native service over a Packet Switched Network (PSN). The native service may be ATM, Frame Relay, Ethernet, low-rate TDM, or SONET/SDH, while the PSN may be MPLS, IP (either IPv4 or IPv6), or L2TPv3.
The PW emulates the operation of a "transparent wire" carrying the native service, but it is realized that this emulation will rarely be perfect.
The first PW specifications were the Martini draft for ATM PWs, and the TDMoIP draft for transport of E1/T1 over IP.
In 2001, the IETF set up the PWE3 working group, which was chartered to develop an architecture for service provider edge-to-edge PWs, and service-specific documents detailing the encapsulation techniques. Other standardization forums, including the ITU and the MFA Forum, are also active in producing standards and implementation agreements for PWs.
There are now many PW standards, the most important of which are IETF RFCs
- RFC 3985 PWE3 Architecture
- RFC 4385 PWE3 Control Word for MPLS PSNs
- RFC 4448 Ethernet PWs
- RFC 4447 PW setup using LDP
- RFC 4553 Structure-Agnostic Time Division Multiplexing (TDM) over Packet (SAToP)
- RFC 4623 PW Fragmentation
- RFC 4618 PPP/HDLC PWs
- RFC 4619 Frame Relay PWs
- RFC 4720 FCS Retention
- RFC 4717 ATM PWs
- RFC 4816 ATM Transparent Cell Transport
- RFC 4842 SONET/SDH PWs (CEP)
- RFC 5087 Time Division Multiplexing over IP (TDMoIP)
- RFC 5086 Circuit Emulation Service over Packet Switched Network (CESoPSN)
- RFC 5085 Virtual Circuit Connectivity Verification (VCCV)
as well as ITU-T Recommendations
- Y.1411 ATM PWs
- Y.1412 AAL5 PWs
- Y.1413 TDM PWs
- Y.1414 Voice Services PWs
- Y.1415 Ethernet PWs
- Y.1452 Voice Services over IP
- Y.1453 TDM over IP
- X.84 Frame Relay PWs
