Installation and Administration Guide 403March 2000 Network engineering guidelinesMeasuring the intranet Quality of ServiceIntroductionYou can measure end-to-end delay and error characteristics of the current stateof the intranet. These measurements help you set acceptable QoS standardswhen using the corporate intranet to transmit voice services.Measuring end-to-end network delayThe basic tool used in IP networks to measure end-to-end network delay is theping command. Ping takes a delay sample by sending an ICMP packet from thehost of the ping program to a destination server. Ping then waits for the packet tomake a round trip. The ping output is similar to the following:Richardson3 % ping -s santa_clara_Remote Office4 60PING santa_clara4 (10.3.2.7): 60 data bytes68 bytes from (10.3.2.7): icmp_seq=0 ttl=225 time=97ms68 bytes from (10.3.2.7): icmp_seq=0 ttl=225 time=100ms68 bytes from (10.3.2.7): icmp_seq=0 ttl=225 time=102ms68 bytes from (10.3.2.7): icmp_seq=0 ttl=225 time=97ms68 bytes from (10.3.2.7): icmp_seq=0 ttl=225 time=95ms68 bytes from (10.3.2.7): icmp_seq=0 ttl=225 time=94ms68 bytes from (10.3.2.7): icmp_seq=0 ttl=225 time=112ms68 bytes from (10.3.2.7): icmp_seq=0 ttl=225 time=97ms^?--- Richardson3 PING Statistics ---8 packets transmitted, 8 packets received, 0% packetloss round-trip (ms) min/avg/max = 94/96/112The time field displays the round trip time (rtt).In order for the delay sample results to match what the Remote Office node canexperience, the ping host must be on a working LAN segment attached to therouter intended to support the Remote Office node. The selection of destinationhost is just as important, following these same guidelines for the source host.
