Troubleshooting Enet-attached device

On Thu, 19 Sep 2019 10:16:00 -0500, Mark Lloyd wrote:

On 9/18/19 4:53 PM, Char Jackson wrote:

[snip]

That suggestion is incomplete without also pointing out that no DHCP
server will be available, so assigning IP addresses and network masks
becomes a manual task. Also, it might not be safe to assume Auto-MDI
negotiation, meaning digging up a crossover cable, so a better
recommendation would be to use a cheap switch, where cheap means
unmanaged, but then we're back to talking about the switch that comes as
part of the router package.


Or a separate switch. Also, a router could be operated with no WAN
connection so it can't act as a router.

Be careful with that last statement. If a router with no WAN connection
is asked to do routing, it'll be dumping packets into a black hole.

When is a router asked to do routing? When a packet arrives at one of
the router's interfaces and the destination is an address that lies
outside of the local subnet, as defined by the address and netmask
configured on that interface.

Char Jackson wrote:

On Wed, 18 Sep 2019 22:17:34 -0500, VanguardLH wrote:

The Linksys BEFSR41 10/100 router that I got almost 2 decades ago
(came out in 1999) doesn't need crossover cables.

http://downloads.linksys.com/downloa...U_V10_DS_A.pdf
"Automatically Detects Straight or Cross-over Cable"

I also had a BEFSR41 back then, except it was a US version vs EU. No
Auto-MDI for me. Mine had a slide switch on the rear to select
straight or crossover.

Ooh, wow, I haven't seen a BEFSR41 with the slide switch. Guess it was
made back when crossover cables might've still been in use, so a patch
jockey didn't have to rewire their setup (under raised floors, through
ceiling ladders, through walls).

Didn't even need them with hubs.

With what? Hubs? ;-)

It has been probably as long since I've used just hubs. Switches became
just as cheap, so there became no reason to buy a hub. I typically do
cleanup once a year or two. Items that haven't been used in 5 years and
likely see no use in the next 5 years are strong candidates to get
discarded (trashed, sold off, given to the Goodwill).

I think the last person in my family to use an Ethernet hub (probably a
Netgear) was my aunt. I don't know if she still has it. While her
desktop PC is wired, all her laptops, netbooks, and smartphones are
wifi, so if she still has it then it's in storage somewhere, and she is
a hoarder. When she dies, I'm getting 2 or 3 dumpsters to evacuate her
home of all the junk and trash.

In 2011, IEEE deprecated hubds in 802.3. They're around only in really
old setups. Now that I think upon it, the Netgear might've had a slide
switch to decide whether or not to use auto-MDI. Or maybe the switch
was to convert one of the RJ-45 ports from a normal to an uplink port.

http://www.downloads.netgear.com/fil...106108ints.pdf

Section 4 has a chart showing the use of either straight or cross-over
cables. Because they list only N-1 of the ports as adaptable, I suspect
the missing one (4th in a 4-port EN104, 8th ine an 8-port EN108) was the
switchable one for uplink mode. The EN10x boxes are 10/100Base-T. I
could not find when Netgear introduced those models. The doc above has
a copyright of 1998.

Oh, look, I found one for sale at $170:

https://www.newegg.com/netgear-en104...82E16817111503

Must be like antique cars: the older (and still in good condition) then
the higher the value. For that price, you could buy 4 BEFSR41 routers
or a dozen switches. You'd have to buy one that's used to get a cheap
price, but you can used switches for cheap, too.