What is
MPLS (MultiProtocol Label-Switching) ?
MPLS (MultiProtocol
Label-Switching) is a standard proposed by IETF, the Internet standards
body for all architectures and high-level protocols (IP, IPX, AppleTalk, etc.).
However, his most typical implementation concerns the IP protocol only.
The specific transfer nodes used in MPLS are called LSR
(Label Switched Router). The LSR act as switches for user data streams and as
routers for signaling. To route user frames, use references or labels. At an
input reference is a reference output. The succession of reference defines the
route followed by all frames containing the stream of IP packets.
MPLS
Features
MPLS is
the logical culmination of all the proposals that were made in the 1990s of the
IETF The idea was to propose a common standard for transporting IP packets over
subnets working in switched mode. The nodes are switch-capable routers back or
at the IP level for performing routing, either at frame level for switching.
The most important features of the
MPLS standard are as follows:
• Specify the mechanisms for transporting IP packet
streams with various grain sizes of the waves between two points, two machines
or two applications. Granularity refers to the size of the stream, which may
include more or fewer user waves.
• Independence of the frame level and the
packet level, although only transport IP packets to be really taken into
account.
• Linking the IP address of the recipient
with an input reference in the network.
• Recognition by the edge routers of the
type of OSPF routing protocols and signaling such as RSVP.
• Use of different types of frames.
Some additional features are worth noting:
• Opening the path based on the topology,
although other possibilities are also defined in the standard.
• Assignment of references made by the
downstream, that is to say, at the request of a node issues a message in the
direction of the transmitter.
• Granularity variable references.
• Stock references managed according to
“last in, first served” method.
• Ability to prioritize requests.
• Use of TTL timer.
• Encapsulation of a reference in the
frame including a TTL and a quality of service .
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