Nortel 6220 User Manual page 152

156
8. Please provide the list of parameters for the different levels of signal
strengths i.e. No Connection, Poor, Acceptable, Good, and Excellent. How
do I determine what is good and bad?
What these values will mean, is somewhat specific to the environment being
worked under. For example, a Signal to Noise Ratio of 15 may be fine for one
area and 15 may not work very well in a high noise area. So here are some
general guidelines. Keep in mind all the information below is related to Secure
Data mode, for 802.11b mode replaces retransmit with dropped packets:
There are some further items to note:
Link planning should be done in your general geographic area and your links
should be set up with an extra margin that your company determines.
Links are best performed when possible with high gain antennas as opposed to
low gain amplified antennas
Noise is typically introduced by failing amplifiers and problems with connectors
and defective radios. Signal typically drops with bad cabling, connectors or
antenna misalignment, radio power issues Network ID and Channel values being
the same, may help stability in marginal links.
Marginal (sporadic links) typically occur in SNR ranges from 5-9, 10-15 usually
will keep association with retransmits or some packet loss. SNR from 16 and up
usually are acceptable for every day operation.
If SNR is over 25 and throughput is poor, overdriving or multi-path may be the
cause of the problems.
Secure Data Mode Station Entries - Provides information on octal packet,
retransmitted packets and failed packets. A value other than 0 under failed
packets typically points to a link issue. Keep in mind TC retransmits a packet 9
times, (with the initial packet 10 total).
This has occurred and the packet has been dropped when a failure occurs.
Retransmits should be 15% or less of total transmits, this may indicate signal,
noise or antenna alignment issues.
Remote Statistics - Check each Ethernet Interface, any errors or collisions may
be signs of link speed or greater network related issues.
Check each wireless interface. Specifically, compare the Frame Check Sequence
errors to the bytes in values. Typically FCS occurs on any wireless connection.
This should only be a concern if the value exceeds approximately 10% of the
bytes in value. This may be an indicator of signal/multi-path issues.
WLAN Cable Access Point 6220 CSU NTPM99CA Rel 2.0 Issue 5 Dec 2005