School network. Connectivity issues.

Hi,

We are experiencing problems with our 700 client Server 2003 network. Our XP
clients lose their mapped drives from time to time which is always resolved
by a logout / login. Printers go offline and then come back online.

Pings to clients / fail and then start working again. Our network has
recently had a wireless network connected to it and this has coincided with
problems. Interestingly we had a similar problem in September 2004 when we
rolled out our own wireless network. We took that offline in September until
a week ago when the experts came in and comissioned a new wireless network.

Our network backbone is made up of gigabit 3Com 4200 series switches
interconnected by fibre over two different sites. Our servers are connected
by gigabit copper to our gig 3Com 4200 switches. Our large rooms (30-33 pcs)
have 100 base TX to each client with a gigabit uplink to the switch that
feeds the room.

We are really stumped with what's happening. When we last saw this problem I
posted here and Ron Lowe posted and interesting reply. Anyone wish to add to
this see:-

http://groups.google.co.uk/group/mic...5a35ca734d25af

We also have a new 35 odd AP wireless network USR 5450 with another hundred
or so wireless portable linux based electronic folders for registration. Oh
and add in about 150 XP wireless laptops.

Our network is fully switched but we have only the one broadcast domain. We
don't do any routing at all.

Thanks very much

Andy

You are having this roblems in your wired network, right?
How the clients have ip configured? Static? Dynamic?
Dynamic?Dhcp have scope with ips for all the clients?


"Andy" wrote:

> Hi,
>
> We are experiencing problems with our 700 client Server 2003 network. Our XP
> clients lose their mapped drives from time to time which is always resolved
> by a logout / login. Printers go offline and then come back online.
>
> Pings to clients / fail and then start working again. Our network has
> recently had a wireless network connected to it and this has coincided with
> problems. Interestingly we had a similar problem in September 2004 when we
> rolled out our own wireless network. We took that offline in September until
> a week ago when the experts came in and comissioned a new wireless network.
>
> Our network backbone is made up of gigabit 3Com 4200 series switches
> interconnected by fibre over two different sites. Our servers are connected
> by gigabit copper to our gig 3Com 4200 switches. Our large rooms (30-33 pcs)
> have 100 base TX to each client with a gigabit uplink to the switch that
> feeds the room.
>
> We are really stumped with what's happening. When we last saw this problem I
> posted here and Ron Lowe posted and interesting reply. Anyone wish to add to
> this see:-
>
> http://groups.google.co.uk/group/mic...5a35ca734d25af
>
> We also have a new 35 odd AP wireless network USR 5450 with another hundred
> or so wireless portable linux based electronic folders for registration. Oh
> and add in about 150 XP wireless laptops.
>
> Our network is fully switched but we have only the one broadcast domain. We
> don't do any routing at all.
>
> Thanks very much
>
> Andy
>
>
>
>

"NunoCosta" <(E-Mail Removed)> wrote in message
news:8139B524-0CAF-45FE-963B-(E-Mail Removed)...
> You are having this roblems in your wired network, right?
> How the clients have ip configured? Static? Dynamic?
> Dynamic?Dhcp have scope with ips for all the clients?
>
>

This is happening with our wired network yes. Our clients have static
addresses though we do have a dhcp server for ris and VPN.

We also have a 35 AP+ wireless network overlaid on our wired network.


Andy

Why you do not use VLAN's
Try to stop wireless broadcasts in AP's
Use the MS Network Monitoring Tool IN add Remove Programs to analyze the
traffic.

--
MCSE w2k
MCSA w2k/ MCSA MESSAGING w2k
MCDBA


"Andy" wrote:

>
> "NunoCosta" <(E-Mail Removed)> wrote in message
> news:8139B524-0CAF-45FE-963B-(E-Mail Removed)...
> > You are having this roblems in your wired network, right?
> > How the clients have ip configured? Static? Dynamic?
> > Dynamic?Dhcp have scope with ips for all the clients?
> >
> >
>
> This is happening with our wired network yes. Our clients have static
> addresses though we do have a dhcp server for ris and VPN.
>
> We also have a 35 AP+ wireless network overlaid on our wired network.
>
>
> Andy
>
>
>

You haven't got many replys because we don't clearly see what you have. We
don't care about brands and model numbers and we pretty much don't care
about speeds, so the first post just has too much stuff to "weed" through to
get to the detils we need. If it is wireless or wired doesn't matter.
Whether machines are Static or DHCP really doesn't matter either.

What we need to understand is the Topology and Subnets and how they are
routed together. Also if you have an Internet Sharing Device then called it
a NAT Device (or Proxy if it is a proxy),...don't call it a router because
it will be confused with a LAN Router.


--

Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com


"Andy" <andy@not> wrote in message
news:u%(E-Mail Removed)...
>
> "NunoCosta" <(E-Mail Removed)> wrote in message
> news:8139B524-0CAF-45FE-963B-(E-Mail Removed)...
> > You are having this roblems in your wired network, right?
> > How the clients have ip configured? Static? Dynamic?
> > Dynamic?Dhcp have scope with ips for all the clients?
> >
> >
>
> This is happening with our wired network yes. Our clients have static
> addresses though we do have a dhcp server for ris and VPN.
>
> We also have a 35 AP+ wireless network overlaid on our wired network.
>
>
> Andy
>
>

"Phillip Windell" <@.> wrote in message
news:(E-Mail Removed)...
> You haven't got many replys because we don't clearly see what you have.
> We
> don't care about brands and model numbers and we pretty much don't care
> about speeds, so the first post just has too much stuff to "weed" through
> to
> get to the detils we need. If it is wireless or wired doesn't matter.
> Whether machines are Static or DHCP really doesn't matter either.
>
> What we need to understand is the Topology and Subnets and how they are
> routed together. Also if you have an Internet Sharing Device then called
> it
> a NAT Device (or Proxy if it is a proxy),...don't call it a router because
> it will be confused with a LAN Router.
>
>
> --
>
> Phillip Windell [MCP, MVP, CCNA]
> www.wandtv.com
>
>

Phillip,

Thanks for the tips. here's my attempt to be more succinct

Single site, no routing between any clients. ip address used 192.168.x.y
with a mask of 255.255.0.0 No vlans, Internet access via ISA server (NAT
Device).

Andy.

"Andy" <andy@not> wrote in message
news:(E-Mail Removed)...
> Single site, no routing between any clients. ip address used 192.168.x.y
> with a mask of 255.255.0.0 No vlans, Internet access via ISA server (NAT
> Device).

First:
700 clients is too big for one subnet. Subnets should be limited to 250-300
hosts per segment. Broadcasts which are normal functions for Ethernet will
saturate the lines with 700+ hosts.


Second:
One of the biggest issues with strange behavior is DNS.

You must follow this pattern,.....

1. All machines,... every last one of them,...must use the AD DNS for their
DNS and must not use any other DNS (the DNS Server points to itself). You
AD/DNS uses within its configuration the ISP's DNS or whatever other
"next-in-line" DNS in the Forwarder's List. The Forwarders List is the only
place other DNS Server should ever be listed.

2. You ISA should be configured to allow you AD/DNS to make outbound DNS
queries just as if was a common ISA Client. It is best or at least easiest
to do this running the AD/DNS as a SecureNAT Client.

3. It is *very* important that the ISA's "Internal Network" definition
include all the IP# Ranges used on the privvate side of the ISA. This
includes all the WAN and VPN Links. With the VPNs it is the private IP#
Range at the opposite end of the VPN that is what you are looking at. Also
any DNS-style FQDNs that are part of the Private System must be included in
the Internal Network in the Domains section.

Third:
Mapped drives are always a problem, and always will be. They are a thing of
the past that should eliminated. UNC Pathes and Windows style "Shortcuts"
replace the mapped drives. Shortcuts are just files, similar to the old
Windows 3.1 "Pif" files. Having a network copy a Shortcut file to a Client
machines is no more difficult than trying to have the Client "map a drive"
and is a whole lot more dependable.

Anything else may be hardware related, but that is the best I know to do
with what I know about the network at this point.

--

Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com

"Phillip Windell" <@.> wrote in message
news:(E-Mail Removed)...
> "Andy" <andy@not> wrote in message
> news:(E-Mail Removed)...
>> Single site, no routing between any clients. ip address used 192.168.x.y
>> with a mask of 255.255.0.0 No vlans, Internet access via ISA server (NAT
>> Device).
>
> First:
> 700 clients is too big for one subnet. Subnets should be limited to
> 250-300
> hosts per segment. Broadcasts which are normal functions for Ethernet will
> saturate the lines with 700+ hosts.
>
>
> Second:
> One of the biggest issues with strange behavior is DNS.
>
> You must follow this pattern,.....
>
> 1. All machines,... every last one of them,...must use the AD DNS for
> their
> DNS and must not use any other DNS (the DNS Server points to itself). You
> AD/DNS uses within its configuration the ISP's DNS or whatever other
> "next-in-line" DNS in the Forwarder's List. The Forwarders List is the
> only
> place other DNS Server should ever be listed.
>
> 2. You ISA should be configured to allow you AD/DNS to make outbound DNS
> queries just as if was a common ISA Client. It is best or at least
> easiest
> to do this running the AD/DNS as a SecureNAT Client.
>
> 3. It is *very* important that the ISA's "Internal Network" definition
> include all the IP# Ranges used on the privvate side of the ISA. This
> includes all the WAN and VPN Links. With the VPNs it is the private IP#
> Range at the opposite end of the VPN that is what you are looking at. Also
> any DNS-style FQDNs that are part of the Private System must be included
> in
> the Internal Network in the Domains section.
>
> Third:
> Mapped drives are always a problem, and always will be. They are a thing
> of
> the past that should eliminated. UNC Pathes and Windows style "Shortcuts"
> replace the mapped drives. Shortcuts are just files, similar to the old
> Windows 3.1 "Pif" files. Having a network copy a Shortcut file to a Client
> machines is no more difficult than trying to have the Client "map a drive"
> and is a whole lot more dependable.
>
> Anything else may be hardware related, but that is the best I know to do
> with what I know about the network at this point.
>
> --
>
> Phillip Windell [MCP, MVP, CCNA]
> www.wandtv.com
>
>

Philip,

Well we have had the expert in today (£1000 a day!) and his comments are
intersting. Basically everything is sound save for the size of the broadcast
domain (700+ clients). We had purchased 3 3COM 3226 layer 3 switches to
start vlan'ing and routing our network but apparently they aren't beefy
enough and they are looking at a 3COM 4005 or Cisco based chassis layer3
switch. It's going to cost us a bloody fortune, just the basic chasis is
around £5,000 and I can see that going up towards £10,000 by the time we add
in the extra modules we need. £1 = $1.75

Andy.

"Andy" <andy@not> wrote in message
news:(E-Mail Removed)...
> Well we have had the expert in today (£1000 a day!) and his comments are
> intersting. Basically everything is sound save for the size of the
broadcast
> domain (700+ clients).

I'm skeptical of his assessment about that. I also don't require £1000 a
day.

>We had purchased 3 3COM 3226 layer 3 switches to
> start vlan'ing and routing our network but apparently they aren't beefy
> enough and they are looking at a 3COM 4005 or Cisco based chassis layer3
> switch. It's going to cost us a bloody fortune, just the basic chasis is
> around £5,000 and I can see that going up towards £10,000 by the time we
add
> in the extra modules we need. £1 = $1.75

That sounds fine.
We use an HP5304XL.
I have about $10,000 wrapped up in it. It is the logical "center" of the
network and I use HP2524s throughout the rest of the network at about
$400-$500 each if I remember correctly. Some have Fiber modules, some do
not.
Networks are expensive,...there are no "free lunches".

--

Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com

"Phillip Windell" <@.> wrote in message
news:%(E-Mail Removed)...
> "Andy" <andy@not> wrote in message
> news:(E-Mail Removed)...
>> Well we have had the expert in today (£1000 a day!) and his comments are
>> intersting. Basically everything is sound save for the size of the
> broadcast
>> domain (700+ clients).
>
> I'm skeptical of his assessment about that. I also don't require £1000 a
> day.
>
>>We had purchased 3 3COM 3226 layer 3 switches to
>> start vlan'ing and routing our network but apparently they aren't beefy
>> enough and they are looking at a 3COM 4005 or Cisco based chassis layer3
>> switch. It's going to cost us a bloody fortune, just the basic chasis is
>> around £5,000 and I can see that going up towards £10,000 by the time we
> add
>> in the extra modules we need. £1 = $1.75
>
> That sounds fine.
> We use an HP5304XL.
> I have about $10,000 wrapped up in it. It is the logical "center" of the
> network and I use HP2524s throughout the rest of the network at about
> $400-$500 each if I remember correctly. Some have Fiber modules, some do
> not.
> Networks are expensive,...there are no "free lunches".
>
> --
>
> Phillip Windell [MCP, MVP, CCNA]
> www.wandtv.com
>
>

An update as we have received a quotation from the network engineer:

1 x Cisco 3750G - 24 port x 10/100/1000 switch with Enhanced IOS.

1 x Cisco 3750G - 12 port SFP switch with Standard IOS.

10 x Cisco 1 port 1000 Base SX SFP module



for £13,900



or a

1 x 3 com 4005 chassis with 1 x PSU, 2 x fan, and 1 x Processor

3 x 3 com 2 port 1000 Base T Network Blades

5 x 3 com 2 port 1000 Base SX Network Blades

2 x 3 com 8 port 10/100 Base T Network Blades

1 x 3 com Redundant Power Supply



for £12,630





Our backbone is all 3Com (about 12 switches) and a mix of DLink and Dell
Powerconnect switches in the classrooms. Do we go for the proposed 3Com
solution to match our backbone or is Cisco all the way if we can afford it?
Cisco appears to have built a very strong reputation but is this justified?
Our current backbone usage is in the 1 - 2% range with spikes up to 14%

Any thoughts?

Andy