Bridiging disabled ethernet port?

[Fox5]

I tried bridging my wireless and wired connections at my college dorm...and promptly my wired ethernet port (in the wall) stopped working. What do you think the chances are that if I wait long enough, it will automatically reenable? I don't want to contact tech support since I'm assuming network bridging is not something they wanted me to do. Are there any standard network router policies for this? How can they detect it anyway?

 

[spidey07]

There's a reason it shut the port down. Don't do that. Most likely it takes administrator action to bring the port back up. They can detect a whole lot of stuff - it's all automatic. By you bridging your connections to wireless you are effectively compromising any security. You could actually cause the whole floor or building to not work.

Standard practice is not allow ANY network gear on the ports or anything that could compromise security or stability. Then you use any and all features to detect it and shut it down.

 

[ScottMac]

Not to mention the possible L2 loop & subsequent broadcast storm crippling the switch it's attached to.

OH nuts, I guess I mentioned it ....

 

[zenguy]

And Just contact them and tell them what happened and explain you know now it's something you should not do.

It's not really a big deal.

 

[Fox5]

I'm actually kind of curious what network bridging does that's so bad. I figured it'd all be handled internally and externally would look identical.

 

[ScottMac]

Originally posted by: Fox5
I'm actually kind of curious what network bridging does that's so bad. I figured it'd all be handled internally and externally would look identical.

Well, it can get sort of technical, but the short version is that a "switch" is really a multiport bridge, it acts like a bridge in that it watches what traffic comes from and goes to each port using a table of port/MAC pairs.

On a bridge, any unknown MAC addresses are flooded to all ports except the source, and all broadcasts are forwarded to every other port.

When one port sends a broadcast or multicast (or a flood), the two ports keep forwarding each others traffic, doubling and re-doubling each round until the link is saturated (i.e., "no room for normal traffic" and "no more processor time left in the switch").

In commercial grade switches, there are protocols available (spanning tree, etherchannel, and others) that permit multiple parallel connections to avoid the L2 loop / broadcast storm scenario. Both ends of the (multiple parallel) link have to support the protocol (and most consumer grade switches do not), and they must be enabled (i.e., they don't come up automatically).

Chances are they know you did it, and they're just waiting for youto show your face so they can explain it to you themselves. That's the kind of infor any decent monitoring system can provide.

Good Luck
Scott

 

[spidey07]

This may help. Basically it is a very, very bad thing and can cause bridge loops unless precautions from a network perspective are taken. If these precautions are not taken (shutting down that port) then havoc can ensue. Frames travel around endlessly the loop until there are no resources left and it's doesn't take long.

http://forums.anandtech.com/me..._key=y&keyword1=bridge

Not to mention with today's technology you can detect the wireless card and that it's being seen on the wired side so it could be shutdown that way. There are many tools out there to deal with college networks and it's all done automatically.