Introduction to MPlS and GMPLS
(continued)

Where Networking Is Today

For years now the datacom and the telecom networks have existed in different worlds. Having different objectives and customer bases, each discipline has formed its own language, procedures, and standards.  Placing data on a telecom network was a challenging and often difficult task. Placing datacom traffic onto a voice network required encapsulating several layers.

In Figure 2 column a, we see data traffic stacked on top of an ATM layer.  In order to send this traffic on a SONET network, (figure 2 column b) it was restacked.  And, finally, to place this traffic on an Optical DWDM (figure 2 column c) network, it was stacked again.

Figure 2  Data, ATM, SONET, DWDM

Notice how each layer has its own management and control. This method of passing data onto a telecom network is inefficient and costly. Interfacing between layers required manual provisioning; each layer is managed separately by different types of service providers.  Reducing the number of interface layers promises to reduce over all operational cost and improve packet efficiency.  GMPLS concepts promise to fulfill the aspiration of one interface and one centralized automatic control.

As the telecom world marches towards its goal of an all-optical network, we find that data packets may need to cross several different types of networks before being carried by an optical network. These network types, which have been defined in several draft RFCs, include: packet-switch networks, Layer 2-switch networks, Lambda-switch networks, and fiber-switch (Figure 3).

Figure 3  Different Types of Networks

Where Networking is Going

In Figure 4, we see the promise of GMPLS.  Figure 4a represents where we are now in the datacom-to-optical network interface.  Data from routers goes to ATM switches.  The ATM switches connect to SONET switches, and SONET switches connect to DWDM networks.  As the network migrates, we will find that layers of this stack will begin to disappear.  First, with the elimination of ATM by using MPLS, then SONET for Thin Sonet with GMPLS, and finally to Packet over DWDM with switching (Figure 4d).

Figure 4  The Promise of GMPLS

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