Geek question

[ciphergoth]

About network switches. Can you join two cheapo (Dabs Value) 100BASE-T switches with a crossover cable?

One friend argues "no" on the grounds that before any switch will send a packet to the other, it would have to know of an address at the other end, but neither switch will know of any addresses on the other switch until some packets have been exchanged. (Is that right?) This makes sense, but it occurs to me that if switches broadcast any packets they don't know how to route then all will be well. I don't know if they do though.

I also have no idea what to do if I can't connect them this way! Possibly buy another PCMCIA Ethernet card for the laptop that's also the gateway, but they are costly.

Advice gratefully received...

Comments

[(Anonymous)]

Hiya,

You should have no problems doing what you suggest with a pair
of those Dabs value switches. I've just had a look at their
specs and two things are in your favour - i) there's specific
mention of using them with hubs and other switches, and ii)
there are no "red flags" in the specs suggesting they won't do
what you want. And the prices are truly amazing. I cannot
believe an 8-port 10/100 switch goes for 12 quid, VAT included,
these days - what value!

In the very early days of switches - and I'm talking maybe 8 or
9 years ago here .. - what you generally found was that most
ports on the switch could only learn one MAC address. Only a
single ethernet device, e.g. one server, could be plugged into
these ports. You then had a limited number - maybe just two -
of ports which could handle multiple MAC addresses. These were
the only ones that hubs or switches could plug into, as multiple
MAC addresses would come from them.

Soon after this, switches evolved so that any port could learn
multiple MAC addresses, meaning hubs and other switches could
just be hung off any port that was convenient.

And that's what every switch seems to do these days, even the
very very cheapest.


The link below is to a set of web pages that have a very clear
explanation of ethernet technology and devices. Starting from
the basics of how LANs and ethernet bridges work, they explain
how switches are really just multiple port bridges. And they do
this with lots of clear pictures and handy hyperlinks.

http://www.erg.abdn.ac.uk/users/gorry/course/lan-pages/bridge.html

Good luck with your networking!

[ciphergoth.livejournal.com]

Thank you, o anonymous person (?), this is very useful information. The link is very nice and confirms the way I suspected switches might work.

Now all I have to do is diagnose and solved this weird packet loss problem - which might be the subject of yet another LJ post...