MPLS
(Multi – Protocol Label Switching)
MPLS Overview (What is MPLS?)
Over the last few years, the Internet has developed very quickly. So, it can drive a variety of
new applications to evolve too. These new applications also know as real time application, including
new voice, picture and multimedia services are being developed and deployed into present-day
network technologies. That is the reason why we should to develop telecommunication and network
services for support many new application which establish in this time. Therefore, the new core
network technology such as MPLS is an interested solution that it will play an important role in the
routing, switching and forwarding of packets through the next-generation network in order to meet
the service demands of the network users.
MPLS or Multiprotocol label switching is a new network protocol that defined a mechanism
for packet forwarding in network router. It was originally developed to provide faster packet
forwarding than traditional IP routing by IETF (Internet Engineering Task Force), a large open
international standard organization with no formal member for develops and promotes Internet
standards, although improvements in router hardware have reduced their importance of speed in
packet forwarding However, the flexibility of MPLS has led to it becoming the default way for
modern network to achieve Quality of Service (QoS), next-generation VPN, and optical signaling.
Traditional IP networks send and receive data by router using IP packet. All IP packets have a
header which contained the address of source and destination and also keep their data on it.
However, this traditional IP working format, it has a waste of time caused finding the next hop till
steps and the way to send the information to destination. MLPS also uses IP addresses with an
identifier (label) to identify end point and intermediate switches and routers, it can help packet
forwarding send and receive the data faster than tradition IP routing. This makes MPLS networks IP
compatible and easily integrated with traditional IP network.
MPLS Architecture
IP Routing Protocol
Routing
Information
Exchange
Routing Table
Label
Information
Base (LIB)
Label Generation &
Management
Control
Component
Forwarding
Component
Label Forwarding
Information Base
(LIFB)
Incoming
MPLS Packet
Packet Forwarding
Outgoing
MPLS Packet
The MPLS architecture is divided into two components. The first is called the control
component (the control plane). It created and maintained label-forwarding information surrounded
by a group of interconnected label switches which IP routing protocols can exchange routing
information and another component manages label distribution. It also maintains label information
base (LIB) and create a label forwarding information base (LFIB). The second is called the forwarding
component (the data plane). It uses a label-forwarding database maintained by a label switch to
perform the forwarding of data packets based on labels carried by packets which packet ask the LFIB
for proper forwarding in an outgoing direction.
How do MPLS work?
MPLS operates at an OSI model layer between Layer 2 (Data Link Layer) and Layer 3
(Network Layer), so it is often referred as a Layer 2.5 protocol. It combines the benefits of packet
forwarding based on Layer 2 switching with the benefits of Layer 3 routing.
The main function of MPLS is organizing the path of packet or new routing in the particular
path which referred to as a LSP (Label Switch Path). When a packet is received, MPLS adds a Label in
front of a packet as another header, so that routers know how to act based on this label. Routers
must be label-switched routers (LSRs) and each LSR must maintain a valid mapping from the label of
an incoming packet (incoming label) to a label to be attached to the packet before being sent out
(output label). The router uses the label to identify the LSP. Then, it looks up the LSP in its own
forwarding table to determine the best path over which to forward the packet and the label to use
on this next hop. A different label is used for each hop, and it is chosen by the router or switch
performing the forwarding operation. This allows the use of very fast and simple forwarding engines,
as the router can select the label to minimize processing. An LSP must already be established
between two routers so that packet can follow this path. To establish a path, a label distribution
protocol is used. How do we know this is the best path for the particular class of traffic flows? This
will depend on the traffic engineering requirements of the network and on the service requirements
of the traffic flow to be traffic flow to be carried by the LSP.
As MPLS uses only the label to forward packets, it is protocol-independent, hence the term
"Multi-Protocol" in MPLS. Packet forwarding has been defined for all types of layer-2 link
technologies, with a different label encoding used in each case.
Advantages and Disadvantages
MPLS is a mechanism in high-performance telecommunications networks, which directs and
carries data from one network node to the next. MPLS makes it easy to create "virtual links"
between distant nodes. It can encapsulate packets of various network protocols. A number of
different technologies were previously deployed with essentially identical goals, such as frame relay
and ATM. MPLS technologies have evolved with the strengths and weaknesses of ATM in mind.
Many network engineers agree that ATM should be replaced with a protocol that requires less
overhead, while providing connection-oriented services for variable-length frames. MPLS is currently
replacing some of these technologies in the marketplace. It is highly possible that MPLS will
completely replace these technologies in the future, thus aligning these technologies with current
and future technology needs. There are five main advantages of MPLS: QOS Capabilities,
performance upgrade, disaster recovery, future-proofing the network and cost-effective.
It also have bandwidth up to 10 Gbps for business customers, can choose the speed of it
between 64 Kbps to 1 Gbps. And there are one main weakness is routing intelligence.
The first main advantage of using MPLS services is its QoS capabilities. This is of upmost
importance for companies utilizing voice and video. Second, performance upgrade, increased
response time and improved application performance is advantages for utilizing MPLS services. This
reduces the number of "hops" between network points, which are the "any-to-any" features MPLS
offers. The third advantage is disaster recovery. These services offer data backup/disaster recovery
capabilities by connecting data centers and other key sites in multiple redundant ways to the cloud.
Unlike Frame Relay and ATM networks, which require either switched or backup permanent-virtualcircuits, MPLS services allow remote sites to quickly and easily reconnect to backup locations, when
applicable. This flexibility is a major advantage of MPLS over Frame Relay and ATM. Fourth, futureproofing the network. Businesses realize MPLS is "the wave of the future" and are making the switch
from Frame Relay and ATM services to MPLS. This switch is mainly for fear that they will be left
behind. Competition is tight among businesses in all industries, so having a more cost-effective and
more efficient network system gives them a fighting chance. The last advantage of MPLS services is
cost-effective. MPLS services are cheaper than Frame Relay and ATM data services between 10% to
25%. If voice and data capabilities are added, the savings can jump up to approximately 40% for the
entire network.
The one main MPLS’ weakness resides in its inability to provide application-level routing
intelligence, a fundamental component for voice delivery. For example, MPLS is not able to provide
alternate routing on the call level to prevent latency, delay, packet loss and jitter for VoIP packets.
To provide the uncongested (low latency, jitter and packet drop) label switched path (LSP) crucial for
VoIP traffic, the MPLS network must be able to recognize the VoIP packets and distinguish them
from data packets on the network. This level of intelligence is not found in MPLS. Just as important,
most VoIP traffic today is long-distance, and much of it is international long-distance, meaning these
calls typically traverse multiple networks (domains). As discussed at the beginning of this article,
MPLS deployments are domain-specific and are therefore not a feasible solution for voice traffic
traversing multiple domains.
MPLS is invented for reducing the procedure of sending data by IP packet. There are many
advantages of using it, such as, QOS Capabilities, performance upgrade, disaster recovery, futureproofing the network, cost-effective, etc. It makes packet loss less and also faster than previous
protocols.
Service provider
MPLS (IP VPN) is a data communication service, which work in a full mesh network, provide
a high reliability and make employee and organization more convenience via LAN, or intranet
including E-Commerce applications.
MPLS allow sending package via IP Protocol on ATM network , which has an ability to handle
huge amount of service with a lower cost, and provide a ready to use service that allow user to
access their network anywhere they want via an LAN, Intranet or Dial connection
MPLS-network consists of routers and switches connected to transport facilities such as fiber
optic links. Customer connects to core network via multiservice edge (MSE) router. The core network
comprises the core routers that provide high-speed connection. An MSE router contains different of
line cards and physical interface to provide layer 2 and layer 3 services.
For the incoming data, external interface will sent data to line card, and then line card will
forward them to the switching fabric. For the out-going data, line card receives packets from
switching fabric and forward them to outgoing interface. All operation will pass through the
switching fabric, which is the heart of the router, and used for switch packets between line cards.
There are 3 popular MPLS service provider in Thailand that is CAT, True and 3BB
CAT provide 2 type of service that are ACASIA Direct IP
ACASIA Direct IP
- LAN and Intranet connection via IP protocol
- Connect LAN and Intranet among organizations
- Port speed up to 2 Mbps
ACASIA Dial IP
- Connect stand alone computer to LAN and intranet by using Dial up connection
- Connect computer to LAN or Intranet via PSTN network with the maximum speed
o
of 56K
- Username and password are required for connection
True provide 2 types of MPLS service, that are MPLS VLL which is a point to point connect, and
MPLS VPN which is point to multipoint. Both type of the service provide reliable and secured
service and support CoS (Customer of service) and QoS (Quality of service) like Leased line and
Frame Relay.
3BB (3 broad band) provide IPMPLS –Leased line for organization that want to connect branch
via core network by MPLS technology. This service support QoS (Quality of service) that have
high efficiency to transfer information, picture video and application that applies in organization.
All of these service providers have the same point to service like offer simple design network
solution, have core network that can support large bandwidth, easily to scale if have new sites is
add to the network, employee can access to all site with single administration, as secure as
Leased Line, Frame relay and ATM. But all of these service providers have a little different in cost,
speed and promotion to service customer.
The future of MPLS
From the details of 4 previous topics, it show you about how MPLS work efficiency and it has
many advantages for present-day network technologies that the reason for why we should to
develop MPLS technology more than this and the most important MPLS evolution will be MPLS
Transport Profile (MPLS-TP) in the future, basically the same as MPLS but with key new features such
as Quality of Service, fast reroute and put that into optical and transport networks that have
typically been based on TDM only, it also improve the level of control from basic MPLS. In addition,
the next key evolution of MPLS is an ideal technology to use for 4G wireless Long Term Evolution
(LTE), focusing on IP over Ethernet as its standard backhaul technology, MPLS can be successfully
implemented on and LTE network that it will be a major asset to LTE service quality, particularly
when it comes to giving priority to voice and video packets.
แบบย่อๆ
Multiprotocol Label Switching (MPLS) is a standards-approved technology for speeding up
network traffic flow and making it easier to manage. MPLS involves setting up a specific
path for a given sequence of packets, identified by a label put in each packet, thus saving
the time needed for a router to look up the address to the next node to forward the packet
to. MPLS is called multiprotocol because it works with the InternetProtocol (IP),
Asynchronous Transport Mode (ATM), and frame relaynetwork protocols. With reference to
the standard model for a network (the Open Systems Interconnection, or OSI model), MPLS
allows most packets to be forwarded at the layer 2 (switching) level rather than at the layer
3(routing) level. In addition to moving traffic faster overall, MPLS makes it easy to manage a
network for quality of service (QoS). For these reasons, the technique is expected to be
readily adopted as networks begin to carry more and different mixtures of traffic.
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