While I'll refine this technically in more detail later on, the basic idea behind MPLS is that with IP based switching of packets, the routing table lookup is a lengthy process with the longest prefix match algorithm. The routing table must be looked up for every packet destination and the routing table entry that matches to the maximum number of bit positions will determine the next hop neighbor and hence the outgoing interface. While hardware based caching is done to increase the speed of this process by different vendors, with loaded routers, this is going to be sub optimal. So, the idea is that you assign the same tag to all destinations that you switch in a similar manner. Now, even if this tag value is a 32 bit number, the comparison will be orders of magnitude simpler than comparing with all routing tale entries and determining the longest prefix match.
This idea was carried in from the world of deceased ATM, and was implemented in various forms by different vendors such as tag switching by Cisco Systems, and later IETF standardized it to MPLS, which is vastly similar to tag switching, yet different in subtle ways. Also, there exists an open source implementations of MPLS to run on Linux, that I am aware of and is availabe at SourceForge. There might be other implementations and implementations for other OSs as well, but we're not concerned with that.
Note that MPLS does not eliminate the need for a routing protocol. Routing tables still need to be built, but the switching of packets is much faster.
Postings related to my progress towards PhD research segment. I will post extracts of my readings. I might have to keep certain things to myself for some time, though, because those would be under development.
Tuesday, December 13, 2005
Sunday, December 11, 2005
Reading started
I met my advisor Dr. Zartash tonight and discussed my research process with him. He said that he'd be going to Korea for a couple of months or so, and meanwhile, I should read the following two:
I am to try to read these before he leaves, (and he doesnt have a schedule for when he will leave) and discuss it with him so that he can tell me where to go next.
I'll keep posting the extracts of what I am reading.
- Paper on IP switching by Peter Newman
- MPLS RFC 3031
I am to try to read these before he leaves, (and he doesnt have a schedule for when he will leave) and discuss it with him so that he can tell me where to go next.
I'll keep posting the extracts of what I am reading.
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