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Differences between MPLS and frame relay

The Multiprotocol Label Switching (MPLS) protocol is a relatively new technology (less than 10 years old), and many organizations have been actively replacing their frame relay networks with MPLS service when their contracts expire. What is MPLS? According to Iain Stevenson, networking analyst at Ovum, "MPLS is a mechanism for labelling traffic flows to define a path through a complex network. A network operator can use MPLS as a management tool, as capacity and routes can be seen."

Would a move to MPLS benefit your organization?

Analyzing the pros and cons will enable you to see if the migration will benefit your company.

The MPLS protocol offers a lot of flexibility. When you hear from the different network carriers, the WAN service is labeled as the "new" frame relay. Why?

Many companies have chosen the solution and many swear they won't go back to frame relay service or point to point circuits.

What is MPLS service and how does it work? How does a MPLS network differ from frame relay network?

When using frame relay, you configure Layer 2 on your router, ending up with a WAN network with a connection to a central cloud. Through that cloud, you have connections (permanent virtual circuits or PVCs) to whichever remote sites you've requested and are paying for. If you have a fully meshed network (where every site has a connection to every other site), you pay for every one of those PVCs, which can become quite expensive.

One of the biggest benefits offered by MPLS is that you don't have to worry about PVCs—nor pay for them. The pricing structure of a MPLS circuit is similar to an Internet circuit; you just pay for the access loop as well as a connection fee. Once connected, you have a fully meshed IP network between all remote sites. That ends up saving companies a lot of money if they have various locations with all sites being able to communicate with each other.

MPLS circuits are not Internet circuits. While these circuits usually ride the same backbone as the carrier's Internet traffic, they aren't public circuits as they have a private IP address structure. Different network providers use MPLS in different ways. For example, when using AT&T, Verizon, Sprint, Qwest, Paetec, Savvis or any other MPLS providers, you actually run the MPLS protocol on the router and label (i.e., tag) every packet that goes out to the network.

Another great benefit of MPLS is that you can use the full port speed of your circuits. There are no more committed information rates (CIRs) and no more forward explicit congestion notifications (FECNs) or backward explicit congestion notification (BECNs). Just like Internet service, if you buy a 1544-K T1 Internet circuit, you can use 1544 K of bandwidth, both upload and download.

After setting up the MPLS connections, you have this fully meshed network between all remote sites. How do you route between all of these sites? A routing protocol is needed. You can use either static routes or a dynamic routing protocol such as EIGRP, OSPF, or BGP. With a dynamic routing protocol in place, every site can learn about the LAN's at every other site, and you have a fully meshed and converged network. With static routes, it is not the ideal option when you have more than a few sites especially if you want them to be fully meshed together.

With frame relay, the provider's frame relay switches swap the frame packets based on data link connection identifier (DLCI) numbers. The switches don't look at the IP information, nor do they need to. With MPLS, this is not the case. The switches look at the IP source and destination of the packets because their IP routers are critical IP routers on your network. That means they must participate in whatever routing protocol you choose. If they're routing packets for you, they must have your routes.

If you decide to migrate to an MPLS network provider, and you run Open Shortest Path First (OSPF) as your dynamic routing protocol, all sites have to have access to every other site. At the central site, you have an Internet circuit.

Think of the MPLS provider's router as the "big" router in the cloud. All of your routers connect to its router, and you're routing the traffic together. Who's responsible for routing MPLS traffic? The MPLS providers are responsible for the routing.

If you make changes to the routing protocol, you may need to request that the provider reconfigure its routing protocol. In most cases, however, you can just add a new LAN subnet without informing them at all, and the dynamic routing protocol does its job. Or, if you want to do this without involving the carrier, you could distribute a default route through the dynamic routing protocol and assuming the carrier doesn't have any filters, the remote routers should be able to access the Internet using this default route.

Another option is to use the static route mentioned above. However, the next-hop router would be the carrier's router in the cloud, and the provider would have to configure a static route to point to your central router (to complete the connection).

When working with MPLS, it's critical to remember that both your organization and your carrier are responsible for the routing of MPLS traffic. Some may view this is a drawback, but it has worked well for many organizations small to large.

The fully meshed features, full bandwidth, and simple configuration of MPLS networks are advantages of making the move to MPLS networks. Carrier-based MPLS service is a huge improvement over the old frame-relay network service, and the transition is well worth it. In order to get MPLS prices, request MPLS quotes on shopforbandwidth.com . They have helped numerous clients migrate to MPLS services smoothly.

Article Source: http://www.contentspool.com

Alain Nguyen has been involved in the Telecom/Bandwidth industry for over seven years.We offer you a convenient service to find the best deal on T1 lines, T3 lines or DS3 lines, OC3 Connections, MPLS, Frame Relay, VPN, FastE,Point to point T1, point to point T3 or DS3 price, etc.
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