Apply 802.1p priority at Layer 2 of the OSI model or DiffServ (RFC 2474) service tags at Layer 3. Then, once packets are labeled, act on them as they pass through supported devices using a prioritized queuing mechanism like WFQ (Weighted Fair Queuing) or CBQ (Class-based Queuing), or establish a specialized route using RSVP (Resource Reservation Protocol). Priority settings can be applied in the end user's system if the application supports it. If not, they can be applied in multilayer switches and other devices, such as packet shapers from the likes of Packeteer or Allot Communications. But remember, prioritization schemes do not guarantee delivery. There won't be a new tool in 2004 that will guarantee TCP/IP traffic over the network. But the devices out there to optimize network performance are more mature and widely supported in network infrastructure.
We don't recommend swapping a perfectly good legacy telephone system for VoIP. Most companies considering VoIP are moving into new quarters or have an aging phone system that must be replaced. If this describes you, look closely at VoIP, or at an IP Centrex system from a service provider (see "Centrex, IP Style"). VoIP systems tend to be easier to administer than IP Centrex because they're more user-friendly.
To ensure your implementation is up for the long run, carefully consider SIP (see "It's Time To Take a Look at SIP"). SIP has emerged as the successor to H.323 to deliver a standards-based VoIP phone system for enterprises. This will impact other real-time communications technologies like instant messaging, presence management and unified messaging and facilitate delivery of voice over 3G wireless and cable networks. And like H.323, SIP will make it easy to add voicemail, IVR (interactive voice response) and "click-to-talk" features. With a simple infrastructure consisting of SIP proxy and registrar servers, you can orchestrate call requests to SIP-compliant devices and manage presence.
When buying SIP devices, watch what vendors do rather than just listening to what they say. Many VoIP suppliers, including Alcatel, Cisco, Interactive Intelligence, Mitel and Siemens, are touting new SIP-compliant products. Even Microsoft has incorporated SIP into its XP Messenger client on every XP desktop. Make sure the devices you pick adhere to the SIP standard.
Because the demand for videoconferencing products has been sluggish, according to Frost & Sullivan, competitive pressure on vendors could lead to some good deals. Streaming video and videoconferencing are effective tools to enhance communication and collaboration, provide in-house training and increase sales. One key factor in selecting a streaming media system is the encoding scheme or bit rate. Bit rates for encoding video determine your bandwidth requirements as well as the quality of transmission (see "Encoding Schemes" page 62).
Which video server solution you choose depends on the quality of the video and your audience's bandwidth requirements. If you deliver video on your enterprise network, an MPEG-2 or -4 server will do the job. If you plan on sending content over the Internet, you should select an efficient codec, such as MPEG-4, and look at products that support a strategy for DRM (digital rights management) as well as support for wireless handheld devices like 3GPP (Third Generation Partnership Project). A new standard to create, deliver and play back multimedia over high-speed wireless networks, 3GPP uses MPEG-4 to optimize video delivery to wireless handheld devices. And don't be afraid to look at proprietary solutions from Microsoft or RealNetworks that deliver quality video ranging from 300 Kbps to 1 Mbps. Decoders or players for end users are usually free.
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