[geeks] Network Nightmare

[Patrick Giagnocavo]

What I have seen in the past, is a network device that negotiates at half-duplex , then later negotiates at full-duplex, then negotiates at half-duplex etc.

Solution is to set both sides of the Ethernet connection that is affected to full-duplex.

Cheers Patrick 

----- Original Message -----
From: md benson <md.benson at gmail.com>
To: Geeks List <geeks at sunhelp.org>
Sent: Mon, 20 Jul 2020 06:33:38 -0400 (EDT)
Subject: [geeks] Network Nightmare

Hi,

We are having a major issue at $work with or LAN just completely flaking out
or slowing up to a crawl. It usually happens in the morning when people start
coming into work and booting up PCs (which means Ibm not usually on site to
analyse it). Usually disconnecting one of the Area switches from the Central
switch will calm it down, but it can reoccur several times.

We have one central (unmanaged) switch that has the 2 main area switches (also
unmanaged) spurred off it as well as a WiFi AP and a switch on a Fibre line
(via copper to fibre media converters). The main switch then connects to a
Firebox T35 via a single line to the main switch.

The T35, as well as vetting our LAN traffic, routes off-site traffic to 3 WANs
depending if itbs for a specific Cloud service (uses RDP Terminal services
via a permanent VPN over a dedicated VDSL line), VoIP (uses itbs own VDSL
line to prevent internet traffic compromising call quality) or general
Internet (has a general use VDSL line of itbs own).

We have 2 servers (in different places, one in a rack with a dedicated
switch), about 20 client PCs, 2 WiFi APs (with minimal traffic as they are
only accessible through equipment I allow). We will be introducing 18 VoIP
phones also in the next week or so so as you can imagine LAN outages or
blackouts are going to be a major headache.

The infrastructure wiring is all Cat6a (STP) and is less than 3 years old.

Herebs a link to a diagram:

https://www.dropbox.com/s/j4qf3evxqy31xcb/network-2020.png?dl=0

I understand the situation is very vague but I am at a loss to know how to
begin diagnosis of this kind of issue. I canbt just pull up logs for
something at link level with a setup like this, and I lack the expertise to
know the go-to tools or methods in a situation like this.

My only possible notion thus far is we might be overwhelming the Firewall (we
are near itbs recommended limits) but the situation seems more like
something in the LAN is getting stuck in a loop or a bunfight or something.

All help and suggestions gratefully received.

b

Mark
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