History - Harris Stratex Eclipse 4.6 User Manual

Chapter 2. Eclipse Terminals
Maximum Frame Size
Maximum Frame Size sets the largest size frame for the interface, which determines the
largest datagram than can be transmitted without it being broken down into smaller
units (fragmented). The IDU ES supports two maximum frame sizes, 1518/1522 bytes
(1518 for non-tagged frames, 1522 for tagged frames) or 1536 bytes.
Latency
Network latency refers to the time taken for a data packet to get from source to
destination. For an IP network it is particularly relevant to voice (VoIP) or video
conferencing; the lower the latency, the better the quality.
For phone conversations a one-way latency of 200 ms is considered acceptable. Other
applications are more tolerant; Intranet access should be less than 5 seconds, whereas
for non real-time applications such as email and file transfers, latency issues do not
normally apply.
Other contributors to overall latency are the devices connected to the Eclipse network,
which for a VoIP circuit will include the external gateway processes of voice encoding
and decoding, IP framing, packetization and jitter buffers. Contributing to external
network latency are devices such as routers and firewalls.
Table 2-11 lists typical one-way performance over a 100 Mbps IDU ES link.
Table 2-11.
Frame
Size
64
128
256
512
1024
1518
Ethernet Diagnostics
Portal diagnostics screens capture Ethernet performance and history. The data for IDU
ES includes:
• Port/channel status.
• Configured capacities.
• Graphed current Rx and Tx throughputs and discards per port and channel.
• Graphed historical Rx and Tx throughputs, frame type and discards per port and
channel.
• Historical statistics per port and channel.
• Comprehensive RMON performance statistics per port and channel.
• Event history.
For more information refer to the following topics in Volume IV, Chapter 13.
Vol. II-2-20
Typical Performance for a 100 Mbps Hop
Latency Throughput
240 uSec 72 Mbps
250 uSec 83 Mbps
270 uSec 88 Mbps
300 uSec 93 Mbps
390 uSec 95 Mbps
460 uSec 95.5 Mbps
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