Code
Marcelo Araujo
Copyright © 2008 Marcelo Araujo
This research are based in some technologies existing in the market, all papers and documents used in this study are available on the Internet and are referenced in this document. If you want to use this document how reference in some project, please don't forget the credits.
Introduction
MPLS(Multi Protocol Label Switching) a new emerging technology's appears how proposal to resolve some overheads caused by IP ROUTING. Imagine a letter with a lot of informations and you need to take a decision in minor time, each information consume a time to read, after of read, you can send to the destination's. Now imagine that, you have only a field called CEP, you consume a minor time to identify the recipient. But we have much more thing's with MPLS technology's as TE(Traffic Engineering), VPN(Virtual Private Network), DiffServ(Differentiated Services) and partially RSVP(Resource ReSerVation Protocol) based on RFC 2205.
References
Finished
~~http://www.iec.org/online/tutorials/mpls_traffic/topic01.html~~
~~http://www.gta.ufrj.br/grad/01_2/mpls/mpls.htm~~
~~http://www.ietf.org/rfc/rfc3032.txt~~
Started
http://www.convergedigest.com/Bandwidth/archive/010910TUTORIAL-rgallaher1.htm
How this work
The concepts around of MPLS are described here, my research's is focused directly in QoS solutions on this case MPLS have a proposal for this.
Multi Protocol Label Switching defined by Cisco:
MPLS is an efficient encapsulation mechanism that uses 'Labels' appended to packets for transport of data. MPLS can run on other layer 2 technologies such as ATM, FR, PPP, POS, Ethernet. Other layer 2 technologies can be run over and MPLS network. MPLS is a technology for delivery of IP Services based on the label-swapping and forwarding paradigm.
The main concepts:
The main point is decrease of work within routers processing the IP header and to break the traditional routing paradigms such as IGP, RIP, OSPF, EGP and BGP4. Complete supporting in end-to-end QoS solutions and traffic engineering. Also important to remember the compatibility between networks IP and ATM.
How MPLS can decrease IP processing:
It is very common for the router open all packages to verify the destination before of send for the next hop, some time ago this techniques are efficient because we don't have VoIP, TV and another critical applications inside network Unlike this, the MPLS apply a LABEL between Layer 2 and 3 of OSI model and only manipulate this LABEL within NETWORK, the IP header don't exist any more inside of MPLS network, just the MPLS LABEL. The LABEL have 32bits of fixed size, specified by RFC 3032, this is a standard and not should be resized.
You must be thinking: IPv4 have 32bits too. You are right about that but you forgot to add some another values as: Frame Format and what the transport layer you use to transport your packages. As an example you must close look in RFC 894 that define as IP datagrams are transported over Ethernet Networks. But MPLS have much more functions and benefits although my focus is QoS.