The second incoming frame is held in a buffer at the switch until the transmission of the first frame is completed. The delay that results is dependent on the length of the first frame. Since Frame Relay allows variable length frames, this delay is variable and unpredictable, resulting in jitter. If this jitter exceeds the ability of the receiving device to compensate by buffering , video quality will be degraded. However, for the majority of public Frame Relay networks, jitter is more a theoretical problem than a real problem.
Public services run on high-speed backbones.
Since delay is inversely proportional to speed, this means that delay at intermediate nodes is highly unlikely. Cell based systems cut packet into fixed sizes Dropped frames are potentially a more serious problem. If some intermediate switch on the network becomes congested, these frames may be discarded. While an occasional lost frame will not seriously degrade video quality, too many will cause a noticeable loss of video quality. In most networks, dropped frames are unlikely to occur.