--- TIC-TECH message:
Somehow, I missed the original message here on who made the district
networking standards. People who know me know that I don't always go along
with the district's standards. But, if I had been asked by "them" who put
together the standards in this case, I would have come up with exactly the
same ones. In fact, I would have also made the standards include what
Protocols were acceptable. Many (most) of our schools use protocols that
broadcast signals repeatably and reduce bandwidth. In fact, before the
district came out with their AT standard switches, the last switch that I
bought a couple of months ago cost $100 for five 10/100 ports. So, I was
quite pleasently surprised to find a cost of 2/3 of what I paid for eight
ports. I have used Allied Telesyn Hubs with no problems. In fact, all of
our Cisco Academy classes around the district use Allied Telesyn hubs which
do work well with Cisco equipment.
I've already campaigned for switches over hubs. I didn't know the real
differences until I completed my Cisco training. But, now, I'm not inclined
to use Hubs for anything over say 20 computers. And, remember that the
number of computers that are on the same network are not just the number of
computers in a room, but in the whole building that are connected to the
Internet. At Ingraham, this is about 300 computers. I often rebuild
computers' software by "cloning" computers which pulls down data at 80 MB
per second. On a "normal" system with Hubs, this will swamp the whole
building down to a dead crawl. You can click on an icon on any other
computer in the building and wait five minutes for the application to
startup or to even start to logoff. But, if the server that I pull down the
clone image from is on a switch, the rest of the school can still operate
normally. I usually clone eight or so computers at the same time and with
switches it is little to no problem for everyone else.
Hubs give you giant shouting matches. This wasn't too much of a problem
with 30 or less computers or even more computers operating at less than 90
Mbps. But, with more and more computers getting connected to the internet
in schools and faster and faster computers, you reach a critical mass and
performance takes a hugh hit. The collisions become unbearable. It is neat
to see this on hubs that show collisions. It is easy to see 100% collisions
in a lot of sites. Not good. Not good at all. PC networks with hubs are
just a small step up from Macintosh computers using LocalTalk daisychains
with telephone wires.
Over the last ten years or so, I have had many oppertunities to work with
Judy McNamee. She has always given me good advice, along with good
explainations when I asked for them. I have never found her to defend a bad
decision by the district. So, I trust her explainations like the ones that
she gave on this topic. The fact that we both thought alike didn't hurt either.
So, why not just ignore the district networking standards if you don't agree
with them or want to buy cheaper devices? If you understand the networking
on the seven levels of the OSI model, then you already know that the
standards are correct (necessary). But, more important, the district can
NOT support substandard systems. Multiply eight ports per room by the number
of classrooms in the district and you'll get numbers that are hard to
support even with everyone following the networking standards. If a
school's Internet connection has slowed to a crawl and someone comes out to
try to fix it and finds substandard networking, ie Hubs, not switches and/or
two or more Hub hops, how can they even start to troubleshoot the problems?
These systems just can NOT be supported. Before I would even start to work
on a system like that, I would tell the site that I will return only after
the network meets the district standards. This would be like trying to work
on a car's transmission when the car's engine doesn't run. I can't work on
the transmission until I know the engine isn't the problem.
The physical parts of networking are extremely simple. Deceptively simple!
Pull cables from one point to another, put RJ-45 connectors on the ends of
the cables, and plug the cables into hubs...sometimes two, three, or four
hubs in a string. But, to have the network work well and work with more and
more devices connected and faster and faster computers takes a lot of other
learning and understanding. The 5-4-3 rule (which we can't use in our
schools). Latency. Store and hold. Cut through. Micro-segmenting, etc.
If you haven't taken $2800 worth of Cisco classes, then you will need to
just accept what the district has developed as standards. Actually, $2800
of Cisco classes doesn't always take hold.
The people who set these standards do know what they are doing. The WAN and
LAN wiring projects are quantum leaps from what any school was doing before.
Ingraham has had network data wiring for eight years. But, the WAN and LAN
wiring puts us into a brand new ball park and we need to update much of what
we have already done or we just degrade the operation of the new system. I
have worked with a number of the people setting up the new wiring and I have
found them to be really good at their jobs, compenent and dedicated. I have
never before found a group of people that I respected as much. With some of
them, I walked through every classroom in Ingraham and a number of other
offices to develope a wiring plan for now and for the future. We found some
deficiencies in the eight year old wiring and they are building fixes into
the new wiring to not repeat the earlier problems. The people overseeing
the earlier WAN wiring were doing weekly walk throughs the building to find
and have repaired any substandard work. And, their standards were quite
high. And, there was a lot of work that the subcontractor had to come back
and repair. (That subcontractor won't be doing any more work for SSD).
-Wes
wfelty@gte.net
>
> -----Original Message-----
>From: John Keithly [mailto:jkeithly@halcyon.com]
>Sent: Sunday, December 17, 2000 9:02 PM
>To: TIC-TECH@tic.ssd.k12.wa.us
>Subject: Tic-Tech: Unmanaged Switches
>
>--- TIC-TECH message:
>I guess I'm a bit underwhelmed by these REQUIREMENTS.
>
>Just out of curiosity, how were these REQUIREMENTS
>arrived at?
>
>Was this another "flash" district decision arrived at
>without any input from the recipient schools?
>
>I can accept the idea of limiting hops.
>
>Why are wall warts "bad"? Are we now trying to
>look nice?
>
>I'd think reliability and performance would be more
>important considerations. From my own experience of
>3-5 years ago c does not have a reputa-
>tion of making quality hubs. I can't speak for their
>switches. But it does make me a bit suspicious that
>their switch prices appear so attractive.
>
>Better choices could be HP, Cisco, Netgear, Linksys, SMC,
>or Intel. I'd at least like to see some product perfor-
>mance comparisons that demonstrate more than price and
>wall wart issues went into making this REQUIREMENT.
>
>I have the impression that using switches and hubs outside
>of an IDF (such as in a classroom) is not an option. I
>don't think this is pragmatic or sustainable for most
>school usage plans. At Ballard we have many, many ports
>in classrooms but still there are places where local switches
>or hubs make sense for concentrating special configurations.
>
>Just my own opinions here of course....
>
> --John Keithly
> jlkeithly@seattleschools.org
> Tech Support
> Ballard High School
>
>-----Original Message-----
>From: Dahlgaard, Andrew [mailto:ADAHLGAARD@seattleschools.org]
>Sent: Thursday, December 14, 2000 3:29 PM
>To: TIC-TECH@tic.ssd.k12.wa.us
>Subject: Tic-Tech: Unmanaged Switches
>
>--- TIC-TECH message:
>All,
>
>Operations has approved the use of these Allied Telesyn unmanaged switches
>in the schools. The Networking guidelines REQUIRES all switches in MDF/IDF
>are managed Cisco ports. The guidelines also REQUIRE that there be only one
>hop from a managed port i.e., a chain that starts: Cisco port -->AT switch
>--> HP Jet Direct Card is ok while: Cisco port -->AT switch --> AT switch
>--> computer is bad.
>
>Why are these switches are good?
>
>First, it is a auto sensing 10/100 Mb full duplex switch instead of a 10 Mb
>hub half-duplex, (faster, less collisions, and reset of hop count.) Second,
>they have an internal power transformer and a "normal" computer power cable
>to power the unit instead of a "wall wart" external transformer. Next, they
>have a limited lifetime warranty. Last, they will be standard across the
>entire district.
>
>The quotes that we received from Graybar Electric Company, (425)468-5511,
>are as follows:
>
>AT-FS708 10/100 X 8 ports $065.96
>AT-FS716 10/100 X 16 ports $177.69
>AT-FS724i 10/100 X 24 ports $245.47
>
>If you need to add ports at a school, your options are: 1) add ports to the
>Cisco switches in the MDF or IDF; or 2) use on of the AT switch models
>listed above, with the AT switch connected directly to a Cisco switch. These
>options provide the best combination of quality, warranty, and price so they
>have now become the district standard. Schools should no longer purchase
>shared media hubs or generic switches.
>
>Drew
>
>Andrew J Dahlgaard
>IS Project Lead & Acquisitions
>Seattle School District #1
>adahlgaard@seattleschools.org
>
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