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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.
Note: Because data network conditions can vary at different times, collect performance data over
at least a 24-hour time period.
• 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.
• Sniffer: Sniffer is not provided with the Business Communications Manager, but it is a useful
tool for diagnosing network functionality. It provides origin, destination, and header
information of all packets on the data network.
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