her techniques, such as able performance. Also, due to the simpler nature of the Multilink point-to-point (MPP), Link Fragmenting and queuing mechanisms, CBQ can be done in hardware, Interleaving (LFI) and Frame Relay Fragmentation (FRF allowing for greater overall performance. 12), allow network managers to fragment larger packets Most commercially available, converged network de- as well as allow queuing mechanisms to speed the de- vices use one or more of these schemes to support si- livery of Real Time Protocol (RTP) traffic without sig- multaneous voice, data, and video traffic. The vast nificantly increasing protocol overhead or reducing data majority use either a CBQ scheme or a hybrid scheme efficiency. Also, header compression protocols such as where fixed bandwidth, high-priority traffic like voice or cRTP can and should be used between WAN links. video conferencing are queued in a priority queue while Hardware-based cRTP is effective with very minimal the rest of the IP services use some form or WFQ or delays, but software cRTP can add significant delay. CBQ at the second level. VPN (Virtual private network) Other elements that affect VolP There are many definitions for Virtual Private Networks (VPN). For our purposes, VPNs refer to encrypted WAN considerations tunnels carrying packetized data between remote sites. VPNs can use private lines or use the Internet via one or Until WAN bandwidth becomes affordable at any speed, more Internet Service Providers (ISP). VPNs are delivering bandwidth to applications over the WAN will implemented in both dedicated hardware and software, remain a formidable task. When voice traffic is carried on but can also be integrated as an application to existing packet networks, different labeling or queuing schemes hardware and software packages. A common example of function to give voice packets priority over data packets. an integrated package is a firewall product that can Classifier Input flow 1 Scheduler Real time (50%) Input flow 2 Interactive (25%) Output port Input