The paper indeed gave insight on the how’s and why’s of the Internet architecture. It is interesting to see the problems that the architecture they designed have, and made me wonder of the progress that has been made to solve this today. A quick “google” and light reading on some of the problems gave me these results:
1) Lack of sufficient tools for distributed management (especially in the area of routing):
• To help with the issue of routing between gateways, different protocols have been invented to do dynamic configuration of the routing table. Routing Information Protocol (RIP) is a dynamic routing protocol used in local and wide area networks. RIP versions 1 and 2 are considered technically obsolete and more advanced techniques such as OSPF, IS-IS and EIGRP are highly recommended. (For auto-configuration of hosts, DHCP is used.) [2]
• Regarding general management of resources, i.e. services and applications, one popular tool for this is Nagios (I haven’t used this before, just heard of it).
2) Few tools for Accounting:
• Whenever I hear accountability for the Internet, one phrase comes into my mind, Google Analytics; this solution gives the ability to view and analyze website traffic only.
3) Better building blocks to solve the above 2 problems:
• So far, the current major innovation for IP is IPv6 but this doesn’t solve the mentioned problems. Notable features of IPv6 are larger address space and simplified processing of routers [3].
Other problems that I failed to see any progress on:
1) IP header is fairly big, actually the option-less headers of IPv6 is as twice as large as IPv4.
2) The goal of robustness, which led to the method of fate-sharing, which led to host resident algorithms, contributes to a loss of robustness if the host misbehaves.
3) How to give guidance to the designer of a realization, guidance which would relate the engineering of the realization to the types of service?
4) No formal method to describe performance.
In relation with my previous post, it is evident that the end to end principle influenced the design of the Internet; for example, by placing the state of information which describes the on-going conversation at the hosts in order to achieve reliability, rather than to the network. Another example is that the Internet architecture achieves flexibility by making a minimum set of assumptions of functions which the net will provide; this lets the applications choose the type of services that they will need. [1]
Given the goals of the DARPANET, if I were to design my own internet architecture, what would be its goals?
1. The Internet architecture must permit distributed management of its resources.
2. Internet communication must continue despite loss of networks or gateways.
3. The Internet must support multiple types of communications service.
4. The Internet architecture must accommodate a variety of networks.
5. The resources used in the internet architecture must be accountable.
6. The Internet architecture must be cost effective.
7. The Internet architecture must permit host attachment with a low level of effort.
I placed distributed management on top because if different resources are managed by different organizations, then the lost of one resource will not disrupt others and internet communication will still continue. Adhering to the principle of end to end argument, the Internet must support multiple types of service as well as networks in order to be flexible and place function at the end points. Something that is manageable can also be accountable; understanding and monitoring the usage of resources within the internet can help in optimizing it according to usage. As memory and computing power increases, sacrificing cost to achieve the higher goals is acceptable. The idea of host resident algorithms makes host attachment hard because a lot of function is placed on the host; nevertheless, because there is already a large amount of experience in protocols, implementations are now available for a wide variety of machines.
References:
[1] D. D. Clark, "The design philosophy of the DARPA Internet protocols," ACM SIGCOMM Computer Communication Review, vol. 18, issue 4, August 1988.
[2] http://en.wikipedia.org/wiki/Routing_Information_Protocol
[3] http://en.wikipedia.org/wiki/IPv6
No comments:
Post a Comment