Abstract: This paper mainly discusses the outline of the MPLS VPN Layer 3. The information is about the MPLS introduction, VPN, MPLS VPN, Working, VRN Routing Information and BGP distribution. Disadvantages and future security recommendations are also mentioned in the report.
Now a day’s technology is increasing rapidly. Every present technology has been further extended into new future technology. MPLS is mainly introduced to overcome the drawbacks of traditional IP Routing. For distributing Layer 3 routing data different routing protocols are used. Forwarding the packets is based on the destination address. So routing lookups are performed on every node that the packet is forwarded along the path. This routing lookup on each node is a time consuming process. Every router should have the total internet routing information which contains millions of routes. So some requirements are aroused and need to develop a new technology which should satisfy some features. 1. Single infrastructure which supports multiple applications with protection 2. High scalability mechanism i.e. it should be topology driven rather than flow driven 3. Load Balancing traffic
4. Effective usage of network Bandwidth.
5. Simple forwarding paradigm
6. Low usage of Bandwidth.
Every client requires more, faster and better technology to run multiple applications with fewer things. Now MPLS came into picture. This technology is implemented with minimizing delay and packet loss. It is a technology for delivering the IP services. It switches the packets rather than routing the packets to transport the data to destination. The name itself says that it uses the labels for switching the packets. Packets can run on other layer 2 technologies such as ATM, Frame Relay, PPP (Point to Point Protocol). ATM relies on PVCs i.e. it depends on VPI/VCI values, Frame relay depends on VLCI values transferring the packets from A to B within the network we no longer look at IP headers, destination, calculating the best path, looking for the next hop and forwarding to decision. MPLS uses a new entity for forwarding the packets using label. It is a new infrastructure having high flexibility with the present technologies. Labels correspond to Quality of Service. Only the edge router in the network performs a routing lookup. Core routers forwards the packets based on the label lookups and swap the Labels.
Virtual Private Network (VPN):
VPN allow to send/receive data on shared/public network with full privacy. Group of sites which are allowed to communicate with each other. VPNs are defined by two policies
a) VPN customers
b) VPN ISPs
These sites may be present within the same organization or in the different organization, i.e. Internet or Extranet. VPNs may overlap , they can have multiple VPNs in a single organization. They can span multiple service providers. There are two Types VPN:
(a) Overlay VPN (b) Peer to Peer VPN
Overlay VPNs—Virtual Circuits between customer sites i.e. constructing a dedicated leased line between the two customer sites Peer-to-peer VPNs— Service provider integrates/participates with customer network, Here Service Provider takes care of the path between the customer sites. This causes some security issue that is described below. Peer-to-peer is good as less costly but two issues arise
* Service Provider can see routing table of client. So security issue * Duplicate address problem
* So MPLS VPN is solution. How?
MPLS VPN Definition
Before moving to MPLS VPN, VPN is defined as follows:
* An IP based network used for allowing the private network services over the public infrastructure. * A set of customer sites that are allowed to exchange information with each other privately through the Internet or other public or private networks as a medium.
Conventional VPNs are developed by configuring full mesh of permanent virtual circuits (PVCs) for all...
References:  http://www.cisco.com/en/US/docs/ios/mpls/configuration/guide/mp_cfg_layer3_vpn.html#wp1051456
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