Nortel Meridian ITG Line 2.0 Description, Installation And Operation Manual page 70

Page 70 of 302 IP Network engineering guidelines
553-3001-204 Preliminary 0.10 August 2000
End-to-end delay and error characteristics of the intranet must be measured
so that the technician can set realistic QOS expectations for intranet voice
services.
The use of measuring tools requires a starting node and a destination node.
The starting node can be a "PING" (see page 70) host on a LAN segment
attached to the router intended to support the ITG Line 2.0 card node. The
destination node can be a remote subnet. The requirement is briefly described
as follows.
Note: Make sure that the ITG network TOS/DiffServe bytes are set to
their intended operational values before taking measurements.
Criteria
•
End-to-end packet delay:
delay between the time a packet is sent to the time it is received at the
remote end. It is comprised of delays at the ITG node and WAN route.
To minimize delays, the ITG node should be located to minimize the
number of hops to the network backbone, or WAN.
Note: To assure a good voice quality, the end-to-end delay is
recommended to be <= 50 ms.
•
End-to-end packet loss:
that do not arrive at their destination. Transmission equipment problems,
packet delay, and network congestion cause packet loss. In voice
conversation, packet loss appears as gaps in the conversation. Sporadic
loss of small packets can be more tolerable than infrequent loss of large
packets.
Note: For high quality voice transmission, a packet loss of <= 2% is
recommended.
Measuring tools
• PING (Packet Internet Groper)
• Traceroute
Packet delay is the point to point one-way
Packet loss is the percentage of packets sent