[geeks] Network Nightmare

[Nathan Raymond]

Unplug network cables, then plug things in one at a time until the problem
recurs. You can often look at the activity lights and will see a change
when the loop is created, causing the activity to shift to a fever pitch.
When youbve figures out the culprit connection, trace it and you may find
that someone has either plugged a cable back into a wall or maybe there is
a mini switch with two patch cords going into wall jacks or a patch cord
going back into a mini switch under someonebs desk.

It could also be due to a malfunctioning device. Ibve seen some network
devices rarely get into a weird state that only a power cycle fixed.

Long term I highly recommend you replace your unmanaged switches with
managed switches, for a lot of reasons.

- Nate

On Mon, Jul 20, 2020 at 9:07 AM <md.benson at gmail.com> wrote:

> Thanks for the suggestion. Ib ll read up on that and see if itb s something
> we can resolve easily. Any idea of solutions that could be applied?
>
> Sent from my iPhone
>
> > On 20 Jul 2020, at 13:28, Jonathan Katz <jon at jonworld.com> wrote:
> >
> > o;?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
> >> _______________________________________________
> >> GEEKS:  http://www.sunhelp.org/mailman/listinfo/geeks
> >>
> > --
> > -Jon
> > +44 7792 149029
> > _______________________________________________
> > GEEKS:  http://www.sunhelp.org/mailman/listinfo/geeks
> _______________________________________________
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