Router (rooter) thingy update.

Mar 10, 2008 44 Replies

Not knowing much about networks with multiple segments I was wondering how an iffy cable/connector could affect more than just that segment. Then I remembered that the poster said the network was fairly heavyly loaded. Thus any retries required to get past the dodgy bit start to slow things down, then buffers start to fill up, and when they do the "stop sending, we are full" starts to propergate across the network... This would obviously be more of a problem with interdevice links than to an individual device.

This probably explains why some people don't have a problem with cheapo couplers and others do. It would only take a short break in network traffic for buffers to empty and the problem not to manifest itself.

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>> You can't.

I use one (exact unit supplied by screwfix) for short-term hook-ups and it works perfectly well for low-demand domestic LAN

Just get a 15m cable and solve it for good - they're very cheap if you look around

In message , Cicero writes

If you were watching carefully enough you'd know.

Data networks are what I do for a living...

Buffers are not really an issue on switches, or on modern routers, and conversaions would rarely go to just one device.

Where it affects multiple segments, the explanations I can think of are:

Spanning tree instability. In a switched network, spanning tree is used to avoid network loops. There are several different versions of spanning tree out there, but basically it works by listening for and transmitting special packets called BPDUs. When a port first comes on, it does not forward user traffic for at least 30 secs while it listens to make sure there are no other bridging devices connected. If it does receive BPDUs from another device, all sorts of negotiation happens to make sure that opening this link would not cause a link, Obviously something affecting those BPDUS (and even the link status) can affect the whole network, If the dodgy connector goes "one way", things can get very interesting.

The connector is to a server - imagine the connector is on a companies mail server. A dodgy link there will only affect that server, BUT the symptoms will be seen by users across the network.

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