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IP Telephony Configuration Guide

Appendix C

Network performance utilities

There are two common network utilities, Ping and Traceroute. These utilities provide a method to

measure quality of service parameters. Other utilities used also find more information about VoIP

Gateway network performance.

This section also describes the Sniffer utility.

• Ping

• Traceroute

• Sniffer

Ping

Ping (Packet InterNet Groper) sends an ICMP (Internet Control Message Protocol) echo request

message to a host. It also expects an ICMP echo reply, which allows for the measurement of a

round trip time to a selected host. By sending repeated ICMP echo request messages, percent

packet loss for a route can be measured.

Traceroute

Traceroute uses the IP TTL (time-to-live) field to determine router hops to a specific IP address. A

router must not forward an IP packet with a TTL field of 0 or 1. Instead, a router discards the

packet and returns to the originating IP address an ICMP

time exceeded message.

Traceroute sends an IP datagram with a TTL of 1 to the selected destination host. The first router

to handle the datagram sends back a time exceeded message. This message identifies the first

router on the route. Then Traceroute transmits a datagram with a TTL of 2.

Following, the second router on the route returns a

time exceeded message until all hops are

identified. The Traceroute IP datagram has a UDP Port number not likely to be in use at the

destination (normally > 30,000). The destination returns a port unreachable ICMP packet.

The destination host is identified.

Traceroute is used to measure round trip times to all hops along a route, identifying bottlenecks

in the network.

Note: Because data network conditions can vary at different times, collect performance

data over at least a 24-hour time period.

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Avaya IP Telephony Guia de Configuração Página 141