On Tue, Dec 24, 2019 at 7:55 AM Tomas Kuchta <tomas.kuchta.li...@gmail.com> wrote:
> Christmas is slow, so I made an exception and read carefully Russell's lan > loop warning post. > > Now, I have conscious, not unconscious (double negative warning to true > English speakers), desire to try to create and observe lan loops in action > for the first time. > > The problem I am seeking help with, can I create one with 4 port router of > which 1 port is wlan and two cat5 patch cables? > > The router/switch looks this way: > - WAN (eth0) > +- LAN1 (eth1) > +- LAN2 (eth2) > +- WLAN3 (wlan0) > The router is running openWrt. > If it's going to "work" (by which I mean rapidly begin to not-work), you could connect LAN1 to LAN2 with a patch cable and then generate some traffic from wifi. It is quite possible that the switch implements some kind of loop protection. Bridges have spanning tree protocol to prune redundant links, your wifi will be connected to the LAN ports via a bridge. Whether you loop or not will depend on how the switch is implemented. You might need more than two switch ports to make it "work". > > I also have two Linux PCs, one with wlan and eth, one with wlan only; and > already mentioned 2 patch cables: 2" and 3" variety. > > The thing is, I have never consciously experience lan loop. Possibly > because my switches can detect and disable them, possibly because I am too > smart! Not sure which to apply right now. > I've seen it a few times, including at the PLUG clinic a long time ago, on a dumb netgear FS116. Many similar colored ethernet cables, someone (possibly me) plugged one in thinking it went to their device but actually went back to another port on the same switch and very quickly switch operation became much less reliable to the point that it pretty much didn't work anymore. Eric Harrison has at least one story of student-perpetrated network sabotage using a similar-but-intentional technique. > > Wouldn't it be great to mess up my parent's simple network setup, so that > they remember my visit and I can also experience lan loops at the same > time? > > Any advice, I could follow? > > Mery Christmas, > Tomas > > On Tue, Dec 24, 2019, 12:40 Russell Senior <russ...@personaltelco.net> > wrote: > > > Also, the ports on the ER-X are gigabit as well, so practically speaking, > > assuming the switch is connected to one of the ER-X LAN ports, you can > > connect to either. It might be super-marginally better to connect to one > or > > another to reduce contention or switch hops somewhere (which will depend > on > > where the majority of the traffic is occuring), but for the most part it > > doesn't matter. > > > > The main thing to avoid is loops. Don't connect switch ports to switch > > ports, ER-X LAN ports to ER-X LAN ports, or more than one link between > the > > ER-X LAN ports and the switch ports. You'll know if you did this because: > > a) things will start acting very funny and not work very well; and b) > LEDs > > will be blinking furiously. I almost hesitate to mention this because: i) > > you probably didn't read this far; and ii) if you did, it will only give > > you the subconscious idea to try it out. > > > > On Tue, Dec 24, 2019 at 3:27 AM Russell Senior < > russ...@personaltelco.net> > > wrote: > > > > > Where is the switch in your network? I don't recall seeing that detail. > > > > > > On Sun, Dec 22, 2019 at 1:09 PM Rich Shepard <rshep...@appl-ecosys.com > > > > > wrote: > > > > > >> On Sun, 22 Dec 2019, wes wrote: > > >> > > >> > The phrasing here is not as clear as it could be. It sounds like > > you're > > >> > referring to the two connections as if they are totally separate. > > >> > > >> Wes, > > >> > > >> There are three ports on the PoE injector: AC power off the wall wart, > > >> "Data > > >> In" on the PoE injector in which is connected to either the router > (any > > >> LAN > > >> port) or the gigabit switch (any port), and "Pwr+Data Out" which is > > >> connected to the Meraki. My question was to what the "Data In" port > > >> should be > > >> connected: the router or the gigabit switch. Either way, the inejctor > is > > >> between the "Data In" supplier and the WAP. > > >> > > >> > ER-X <-> POE injector (with power supply also connected) <-> Meraki > > WAP > > >> > > >> Thank you. That's what I assumed and asked for confirmation which you > > >> supply. > > >> > > >> Happy holidays, > > >> > > >> Rich > > >> > > >> > > >> > > >> > > >> _______________________________________________ > > >> PLUG mailing list > > >> PLUG@pdxlinux.org > > >> http://lists.pdxlinux.org/mailman/listinfo/plug > > >> > > > > > _______________________________________________ > > PLUG mailing list > > PLUG@pdxlinux.org > > http://lists.pdxlinux.org/mailman/listinfo/plug > > > _______________________________________________ > PLUG mailing list > PLUG@pdxlinux.org > http://lists.pdxlinux.org/mailman/listinfo/plug > _______________________________________________ PLUG mailing list PLUG@pdxlinux.org http://lists.pdxlinux.org/mailman/listinfo/plug
