Is Your Wire Really A Pseudo-Wire?

The animated TECHTip tutorial available here.

PWE [Pseudo Wire Emulation] provides, among other things:

• Multi-protocol tunnels - Multi-Protocol Label Switching, GRE [Generic Routing Encapsulation], IPSec [Internet Protocol Security], etc.

• Emulated VC [Virtual Circuit]/channels inside tunnels (above) with multicast features
• Sub IP Layers for SONET or sub-wavelength transmission
• Attachment VC [Virtual Channels] based on Frame Relay model of DLCI [Data Link Connection Identifiers] mapped to emulated (act like) VCs.

PWE3 was also conceived as a means of emulating Ethernet, Frame Relay, ATM [Asynchronous Transfer Mode], TDM [Time Division Multiplexing], and SONET/SDH

Synchronous Optical NETworks - Synchronous Data Hierarchy and other services across an MPLS/IP network. The term “Dry Martini” comes from the name of one of the members Luca Martini. However, “Martini” is also used to describe a “draft” specification. Virtual Connections across the UNI-User-to-Network-Interface and is 10 bits.

The DLCI is a network routing code, however each carrier may assign their own DLCIs as the packets go from carrier to carrier.

Different DLCIs can be also assigned for each protocol, examples might be:

• DLCI21 assigned IP for access to internet

• DLCI22 assigned DECnet or IBM SNA for mainframe
• DLCI23 assigned IPX for LAN-to-LAN

In addition, sub DLCIs contained in proprietary (company-specific) hardware for integration of voice/data on same PVC such as voice or video over frame relay. In a PWE3-PPVPN [Provider Provisioned Virtual Private Network], there may be more than label. To begin with, IP [Internet Protocol] packets may have a number of labels or “tags” attached to them. MPLS [Multi-Protocol Label Switching] is just one type of label. Here are some terms associated with labeling:

• Push - add a label

• Swap - replace the label
• Pop - remove the label

As if one label was not enough, PPVPNs may add more labels. These labels may exist within the network but may be removed or “popped” as they leave the network to the customer premise or “edge” or LER [Label Edge Routers].

A PPVPN control module adds “pushes” labels and determines routing via LSR [Label Switch Routers] where labels may be “swapped” as they change or cross to other networks called AS [Autonomous Systems]. The term LVC [Label Virtual Channel] has been associated with this emerging concept. As long as each carrier or AS [Autonomous System] knows what value of QoS [Quality of Service] for the label and routes it accordingly, each carrier can determine their own labeling system. That is, if each AS carrier routers video as video or email as e-mail or other known rules, then the packets will be treated with the desired QoS.

TECHtionary Corporation, founded in 2001 and headquartered in Boulder, Colorado, is the world’s first and largest animated (rich media) library/magazine on technology. Get the analyses and more than 2,603+ free tutorials on data, Internet, wireless, VoIP (Internet telephony), PBX systems, central office switching, protocols, telephony, telecommunications, networking, routing, power systems, broadband, Wi-Fi, and other technologies. TECHtionary.com provides “just enough - just in time” critical success information. TECHtionary produces Web infomercials proven to “increase revenues, decrease customer support costs, and increase customer satisfaction.”