tailieunhanh - the best damn cisco internetworking book period phần 7

Tiêu chuẩn này là quan trọng bởi vì, nếu độ trễ tối thiểu là lớn hơn so với yêu cầu của hệ thống nhúng, một hệ thống điều hành khác nhau phải được lựa chọn. 2. Tiêu chuẩn này, m2, xác định các quá trình hệ thống điều hành có thể đồng thời hỗ trợ. | 658 Chapter 6 Quality of Service QoS Per-Interface Compression Link Compression Per-interface compression handles larger packets and higher data rates. It is applied to the entire data stream to be transported that is it compresses the entire WAN link as if it was one application. Per-interface compression uses STAC or Predictor to compress the traffic which in turn is encapsulated in a link protocol such as PPP or LAPB. This last step applies error correction and ensures packet sequencing. Per-Virtual Circuit Compression Payload Compression Per-virtual circuit compression is usually used across virtual network services such as Predictor or STAC and Frame Relay STAC . The header is unchanged during per-virtual circuit compression instead the payload portion is compressed. Payload compression is appropriate for routers with a single interface but does not scale well in scenarios with multiple virtual circuit destinations. Continuous-mode compression algorithms cannot be applied realistically due to the multiple dictionary requirements of the multiple virtual circuit destinations. It places a heavy load on the router for CPU and memory. Packet-mode compression algorithms which use fewer dictionaries and less memory are better suited for packet networks. Performing compression before or after WAN encapsulation on the serial interface is a prime goal. Applying compression on an already encapsulated data payload reduces the packet size but not the number of suits Frame Relay and Switched Multimegabit Data Service SMDS . Applying compression before WAN serial encapsulation will benefit the user from a cost perspective when using where service providers charge by the method reduces the number of packets transmitted over the WAN. To configure compression use the compress interface configuration disable compression on the interface use the no form of this command as illustrated below. router config-if compress stac predictor .