[Discuss] Subject: Re: connection issue

[dmildram at gmail.com (Doug Mildram)]

dmildram> I'm admiring all the Q's and ideas on your networking problem.
John Abreau's workaround idea using eg VONET $26
  wireless bridge to put wired device(s) into wireless use
  was enlightening to me for general home use..., even though
   I got a bit confused on the overall setup he used
   and how that might help wireless clients see each other.
   Tangent/useless: If WIRED clients were ganged together on a mini switch,
   that would usually solve  "clients not able to see each other" !
Obviously.

dmildram> ANYWAYS, ie back to Dan Moylan's quest for WhatsGoingOn :
Symptoms sound much like what a PVLAN does.   From wikipedia:
*Private VLAN*, also known as *port isolation*, is a technique in computer
networking
where a VLAN contains switch ports that are restricted
such that they can only communicate with a given uplink.

dmildram>I ran into this layer2 feature in (odd product, to me) EMC Centera:
one cluster per rack w/many 4-disk 1U boxes AND 2 enetswitches.  Weird
storage.
I worked at EMC many months maintaining a lab of Centeras, before realizing
that within each rack, most nodes were purposefully isolated from each
other,
thus introducing me to the rarely-used Private/restricted-port PVLAN
concept.
After that strange world, I got a much-better-learning networking job.
Pardon TMI.

dmildram> back to Dan and home use/problem:
Lord knows these all-in-one HOME "router" boxes ( AP + switch + router )
keep users less aware of internals, so I wonder how/if PVLAN could have
come to life in a t-mobile router+switch....a possible security feature...
since
you said it worked fine up until a week or so ago!
So while I doubt it, I still Hope This Helps mentally or better.
Sure is hard to "try plugging all into this dumb switch together" for wifi !
p.s. also:
I would be inspecting ARP tables though with *nix#  arp -a
....if ports are isolated, only the client with the target IPaddr would
reply
to an ARP request    ( request/re: the target ipaddr ) if I'm not mistaken.
Finally,  doublecheck that 192.168.0.x has a  /24 (255.255.255.0) NETMASK
   (  various show-me cmds like "ifconfig -a" or "ip a",  or windows
"ipconfig /a" )
but offhand I'd wager anything using 192.168.0.x  keeps the std /24 mask.

     original/early problem post w/o many ideas/replies:

>* dan moylan wrote:
*
>>* the problems keep mounting and puzzling (moan).  computers
*>>* alphacent, aldeberan (both fc36) and rigel (fc27) all show
*>>* as connected on the local t-mobile wireless app, and locally
*>>* with ifconfig.  route shows 192.168.12.0 gateway on all
*>>* three.  they can all ping blu.org <http://blu.org> successfully,
but not each
*>>* other, nor can they ssh into each other.  iirc everything was
*>>* fine a few days ago.  what have i done?  what's going on?*