Friday, July 23, 2010

Types of Pseudowires

Introduction to TDM Pseudowires

Pseudowires(PWs) as a technology originate from the contributions made to
the IETF PWE3 working group, which defined the transport of legacy layer 2
services over an MPLS network. These papers were coined the Martini Drafts
(some were wryly dubbed Dry Martini) after one of the lead authors, Luca
Martini. As such, pseudowires have been in existence for nearly a decade,
mainly in the core and edge of the network, typically transporting ATM and
Frame Relay traffic over a carrier IP network.
RAD has pioneered TDM pseudowires in the access sector, introducing a TDM
pseudowire technology in 1999 at ITU World Telecom in Geneva. Known as
TDMoIP®, this implementation extended the original pseudowire definition into
the access network and to the customer premises. This technology has
enabled carriers and corporate customers alike to provide TDM connectivity
and services over a packet network. TDMoIP pseudowire supports all types of
TDM services: framed, unframed, with or without Channel Associated Signaling
(CAS), enabling a smooth migration to packet networks.

Available Pseudowire Types

Following the successful deployment of TDMoIP gateways by RAD, other
flavors of TDM pseudowires have been developed under the aegis of the IETF.
These pseudowires are known as Circuit Emulation over PSN (CESoPSN) and
Structure Agnostic TDM over Packet (SAToP).

CESoPSN TDM pseudowire technology supports framed and channelized TDM
services over packet switched networks. The main difference between TDMoIP
and CESoPSN is the way CESoPSN packetizes the TDM data. Where TDMoIP
packetizes TDM data in multiples of 48 bytes, CESoPSN uses multiples of the
TDM frame itself.

SAToP (RFC 4553), or Structure Agnostic TDM over Packet, is a TDM
pseudowire technology that differs from TDMoIP and CESoPSN in that it treats
the TDM traffic as a data stream and ignores the framing or the timeslots
(DS0). It provides functionality similar to TDMoIP in its unframed mode.
1] SAToP -- Unframed
2] TDMoIP -- Unfraed , Framed , Channelized
3] CESoPSN -- Framed , Channelized.

No comments:

Post a Comment