Researchers merge IP, frame relay services

Researchers merge IP, frame relay services

By Stephen P. Lewis

Special to GCN

Internet telephony, now in its infancy, is only one of several ways large organizations can get more value out of their networks.

An agency's frame relay network can put private branch exchange users in touch with PBX users at the other side of the network without affecting data traffic on the same permanent virtual circuit.

In comparison with a private frame relay network, the Internet is a chancy proposition for sending plain data at any speed, let alone adding voice to it. Older frame relay networks could experience a renaissance because of research underway on router-based voice transmissions. The research also applies to voice over IP and to a combination of IP with frame relay.

Industry standards in this new arena include pulse code modulation-adaptive differential PCM, low delay code excited linear prediction, channel signaling algebraic code excited linear prediction, the international H.323 videoconferencing and G.729 voice compression standards, and the Frame Relay Forum's FRF.11 and FRF.12 interoperability standards.

IBM Corp. has taken the lead in voice over frame relay, although Cisco Systems Inc. of San Jose, Calif., also has added the capability to its 2600 and 3600 routers.

IBM's 2212 router, with foreign-exchange office, foreign-exchange port or electromechanical voice cards installed, can connect as many as 200 PBX users throughout a frame cloud. Using an IBM 9783 frame relay access device, 1,000 workers could dial and talk long-distance through existing PBXes.

IBM Systems Network Architecture sites with IP data networks can stretch the router voice technology to save on long-distance calls. Intranets could connect via PBXes at local and remote sites.

SNA logs for voice traffic over frame relay and IP are as detailed as those of many network management programs. The logs tell who called whom, how long they talked over which paths and what the channel information rate was.

Don't delay

Everyone would like to see voice technologies converge over the Internet, without any quality of service or latency issues, but that is unlikely to happen soon. An IP phone call over the Internet sometimes encounters 20 seconds or more of delay, depending on the connection and time of day. Private networks deliver much better voice quality from PBX to PBX than the Internet can.

Organizations that are already building VPNs might find it makes more sense to converge data and voice over frame relay than to give up a PVC for Internet telephony.


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