| Luis,
Here is a note that I had sent last month to some folks in a similar position
vs Lannet...
Please refer to the references to Lannet in the July 1995 edition of
Data Communications.
I don't know if you all got a chance to look at the July 95 Stephen Saunders
article but a couple of comments on Lannet caught my eye on page 68...
Saunders states that Lannet's MultiNet hub with the LSE-808 module
cannot run a CRC on the FCS, nor can it filter out run-on packets.
It is unusual that they were the ONLY vendor to not run a CRC and one of
only 4 vendors to NOT catch run-ons...
Lannet's "CRC" response was that they "filter out bad frames by checking their
alignment rather than running a CRC". Their silicon counts the # bits in
the frame and divides by 8. If it divides evenly, then they assume the
frame is good, if not then they assume the frame is bad.
I talked with Saunders and he basically said although it's not as good as a
CRC, it still catches the vast majority of errors and it is simpler to
implement. I don't know about you but I get nervous when an editor of a
magazine singles out 1 product out of 37, says they implemented something
that was less rigorous, and then tells me to "not worry". No hard facts
here but possibility for some good FUD perhaps...
On the run-ons, Lannet says that they "only filter frames longer than 4500
bytes because some of its clients are running specialized banking apps that
generate longer frames."
This one seemed very strange to me. I kept asking myself how they can
they can ship a switch that allows 3x the frame size of a
standard Ethernet packet and consider themselves Ethernet compliant? I would
*assume* that the 4500 byte packets are only allowed in the switch and on the
backplane in pt-to-pt configs, and they must fragment the 4500 byte packets
into 3 1518 byte packets (at least in the IP case where there is a standard
for fragmentation) when leaving the MultiNet hub via an Ethernet port...
If not, how can they be interoperable with other vendors' equipment?
In reality *perhaps* they DO NOT fragment the 4500 byte packets back to
1518 when they send it out of the hub and then they point the finger at the
other vendors when they can't interoperate???
Has anyone out there ever heard of this from your customers as a Lannet-touted
advantage?
Bottom line: I'm sure their marketing guys are touting this as an advantage
and are saying 'we are more creative' and if pressed 'we can handle 1518 byte
packets just fine".
Comments?
Stan
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