zze-DIAB Mohammad RD-CORE-LAN
2007-05-04 09:28:43 UTC
Dear Sir/Madam,
I would like to know how is defined the rate of the broadcast packets,
example the rate of Hello pckets.
In fact this question is derived from the following reference
http://ieeexplore.ieee.org/iel5/4234/28054/01254061.pdf where they
observed:
"We observed that the rate at which broadcast packets were sent was set
to 2 Mb/s while we were using 11 Mb/s for user data. We changed user
transmission rate to other standardized 802.11b rates (1, 2 and 5.5
Mb/s), but the broadcast packets were consistently transmitted at 2
Mb/s...
To be sure that this behavior was not specific to the ELSA cards, we
performed some basic tests on other WLAN 802.11b cards. We found that
Lucent Orinoco cards exhibited the same
behavior but interestingly, both Netgear and Cisco Aeronet differed in
that they transmitted broadcast messages at the same rate as user data.
The different behavior of the network cards
can be explained by different interpretations of the IEEE
802.11specification.
The 802.11b specification is somewhat ambiguous on this matter: the
standard defines allowable broadcast transmission rates in terms of the
infrastructure mode-specific concepts, but is somewhat unclear on what
are the allowable broadcast transmission rates in ad hoc mode
(Independent Basic Service Set) that we were using in our network"
So how is set, and where, that broadcast transmitting speed is 2Mbps for
ELSA AIrlaner MC11 and for Cisco Aironet it is the same as data rate
(and this in ad hoc mode)??
Is it a hardware matter that depend on the manufacturer of the chipset?
And consequently we cannot change that.
Is it a parmeter that we can change in the driver? And in wich case?
Thank you very much in advance
Mohammad Diab
I would like to know how is defined the rate of the broadcast packets,
example the rate of Hello pckets.
In fact this question is derived from the following reference
http://ieeexplore.ieee.org/iel5/4234/28054/01254061.pdf where they
observed:
"We observed that the rate at which broadcast packets were sent was set
to 2 Mb/s while we were using 11 Mb/s for user data. We changed user
transmission rate to other standardized 802.11b rates (1, 2 and 5.5
Mb/s), but the broadcast packets were consistently transmitted at 2
Mb/s...
To be sure that this behavior was not specific to the ELSA cards, we
performed some basic tests on other WLAN 802.11b cards. We found that
Lucent Orinoco cards exhibited the same
behavior but interestingly, both Netgear and Cisco Aeronet differed in
that they transmitted broadcast messages at the same rate as user data.
The different behavior of the network cards
can be explained by different interpretations of the IEEE
802.11specification.
The 802.11b specification is somewhat ambiguous on this matter: the
standard defines allowable broadcast transmission rates in terms of the
infrastructure mode-specific concepts, but is somewhat unclear on what
are the allowable broadcast transmission rates in ad hoc mode
(Independent Basic Service Set) that we were using in our network"
So how is set, and where, that broadcast transmitting speed is 2Mbps for
ELSA AIrlaner MC11 and for Cisco Aironet it is the same as data rate
(and this in ad hoc mode)??
Is it a hardware matter that depend on the manufacturer of the chipset?
And consequently we cannot change that.
Is it a parmeter that we can change in the driver? And in wich case?
Thank you very much in advance
Mohammad Diab