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For data-only network applications, Frame Relay offers a reasonably flexible VPN (Virtual Private Network) solution for today's enterprise user (voice applications are more sensitive to latency on Frame Relay networks). The basic components of a Frame Relay network (and establishing a relay-IP connection) include access from the customer location to a Frame Relay port (for each location), the carrier's Frame Relay network infrastructure, as well as the logical connection assignments, known as PVCs (Permanent Virtual Circuits), which map connectivity between sites.  The diagram above shows the basic components before PVCs are assigned for a network with four locations. The connection showed from the End User to the Frame Relay Port will be some form of local access (56kb or T1 depending upon the bandwidth required). The diagram below shows the same network with PVCs assigned in RED. In this network, all locations can connect to the location on the left. Any connection other than through this host site would have to be routed through the host to another destination.  Carriers charge for each PVC established, so the above network is the cheapest configuration possible. Rate components for Frame Relay networks also include a charge for the CIR (Committed Information Rate) on a per-location basis. While a Frame Relay network offers some degree of flexibility, it does require careful sizing and management since there are many variables to manage, such as the relay Internet protocall. IP Basics An IP network is based upon the Internet Protocol for routing traffic packets. Data packets are encapsulated and typically transmitted in a VPN (Virtual Private Network) similar to the way Frame Relay uses common network infrastructure to route data to the proper location. Though the overall basis for both platforms is similar, IP networks offer some distinct advantages. In an IP network, network managers don't have to be concerned with CIR values on a per-link basis, only the size of the IP access on a per location basis. Also, PVCs don't have to be established in an IP network, any location on the VPN can route traffic to any other location. This simplifies management of a multi-location network significantly, since on the LAN side, IP based traffic already exists, and extending this across a WAN using an IP network is quite easy. Only additional IP addressing tables need to be added for remote traffic delivery. Another distinct advantage of an IP network over Frame Relay is that typical latency is substantially less, offering an improved ability to converge voice over an IP network platform. Voice is more sensitive to latency, so QoS (Quality of Service) routing is required to prioritize voice packet delivery over other data packets. This improves voice quality by ensuring that voice packets are delivered on a more serial basis, as compared to a more random delivery that most data applications can tolerate. If you're considering an IP network, consider also routing intra-company voice traffic over the IP network as well, eliminating metered toll charges for long distance locations.  The biggest advantage of an IP-based network (above) is simple configuration allowing all locations to communicate directly with all other locations. |
Relay IP
