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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.
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.
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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