[geeks] Network Nightmare

[Jonathan Katz]

Sounds like a potential spanning-tree loop among your switches.

On Mon, 20 Jul 2020 at 11:33, <md.benson at gmail.com> wrote:

> 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 Ib m 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 itb s for a specific Cloud service (uses RDP Terminal services
> via a permanent VPN over a dedicated VDSL line), VoIP (uses itb s own VDSL
> line to prevent internet traffic compromising call quality) or general
> Internet (has a general use VDSL line of itb s 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.
>
> Hereb s 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 canb t 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 itb s 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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-- 
-Jon
+44 7792 149029