Policy Routing Triad

   

Policy Routing Triad

Back in Chapter 2, "Policy Routing Theory," you were introduced to the concept of the Triad of Policy Routing. This concept was developed through theory and implementation within the context of the IPv4 networking structure. The core provisions for this concept consist of the definition and scope of action for the three main elements of Policy Routing structures. In review, the three elements are

  • Address ”Provides the mechanism of service location.

  • Route ”Provides the guide to reaching the address.

  • Rule ”Provides the logic structure for selecting route.

As you have seen and explored, each of these elements contains a wealth of detail in use and construct. The interactions between these multi- faceted elements defines the range of actions possible under Policy Routing.

What you saw in Chapter 9, "IPv6," was how the nascent format of IPv6 has made use of some of these constructs and yet seems not to have implemented the core. This will change. As discussed in that chapter, IPv6 is still a very young and sparsely used protocol. Even IPv4 did not need to use Policy Routing in the first few decades.

IPv6 will become the new Internet protocol suite. Many of the uses of the Internet are, as with everything Internet, changing at a rapid pace. Think back merely five years , to the release of the first IPv6 RFC in December of 1995, to see the difference. In 1995, not having a Web address was normal and having one was "cutting edge." Cutting edge is a polite way of saying "too risky" and "fit only for the severely bored." Microsoft was busy dismissing the Internet as a fad and trying to release Windows 95. Novell's NetWare still pretty much ruled the corporate network with IPX. Ethernet was just overtaking TokenRing as the corporate LAN topology.

Now think of today. Not having a Web site or at least an email address indicates you are a nobody. Even if that address is on AOL or MSN or Hotmail, at least you "get it" (whatever "it" is). And that's what makes this entire sequence so downright funny to those of us who remember ARPAnet, BITnet, Vaxen, that newfangled Usenet (remember the old uselessnet jokes ), and specifying email addresses in terms of gateways and uucp paths. Back then many of us looked down on those poor local users (lusers in the trade ) who did not grok the wonders of communicating the computer way.

What will you think when the next generation, or even the one beyond that, walk up to you and tell you about how wonderful this Policy networking stuff is, and how you old fogeys don't get "it"? It will happen. You stand today on the shoulders of shoulders of giants. Much of what is so gee-whiz today has been around for eons as translated into Internet time, and you see that nothing really has changed in computing terms. However, in human terms the change is fundamental.

So it will be when IPv6 finally becomes the only reality in the Internet. The fundamental definitions of the Triad will probably be reworded, but they will exist. And the decisions that drove Policy Routing to what it is today will re-emerge. Networking defines a continuous, multiconnected structure.

Consider the evolution of networks themselves . Think of the early point-to-point structures, such as a mainframe with terminals. Note the evolution into multiconnected structures such as LANs. A LAN defines a group of points that each connect at one location, with the allowance that any particular point may talk to any other point. Now consider that a LAN can be thought of as a single point on a network. Initially, you may have connected your LAN points with a WAN. Traditionally you had a point-to-point WAN, then you evolved into a multipoint FrameRelay, where any point in your corporate network can talk to any other point. Step back once more and look at your entire corporate network as a point, and the Internet as the WAN to all the other points. And for the final consideration, think of your point as having more than one connection into this WAN.

At this stage you see how Policy Routing has entered the game. But that could have happened at any of the transitions between single to multiple connections. Today, IPv6 usage on the current Internet is at the point-to-point LAN stage. When we grow into the full multiconnected WAN, Policy Routing will be implemented yet again to suit the new structures.

In this manner, the basics of the Triad have not and will not change. The implementation and the actual uses will probably differ , in some cases substantially. And new uses not yet dreamed of will burst into life much as the Web transformed the use of the Internet in 1993. The ride will be fun, so long as you want the thrill.


   
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Policy Routing Using Linux
Policy Routing Using Linux
ISBN: B000C4SRVI
EAN: N/A
Year: 2000
Pages: 105

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