prpr
Well-Known Member
I guess that is generations of ingrained ignorance.
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What max current will the rear USB actually supply 5V at?
- Thread starter Owen Smith
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Owen Smith
Well-Known Member
If everyone spoke and wrote perfectly, we would lose regional usage and dialects and the world would be a less interesting place.
gomezz
Well-Known Member
Not really. I have seen someone from the OED say that it is a faux distinction propounded by language snobs. Or was it something I heard Susie Dent say on the radio?
Black Hole
May contain traces of nut
...but then "fewer" falls into disuse and we no longer have the richness of language to distinguish between countable and uncountable objects. It's dumbing down all over again. Susie Dent | language anti-snobs are not necessarily right, it's just their opinion | promoting their own agenda.
How does the switch know where to send packets, or does it just send them everywhere (except the originating port)?
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Wildebeest
Member
I was about to ask the same. It looks like a splitter rather than a switch, ie all the traffic is presented to all the ports. Not that that matters for the intended usage here, but if so then it is misleading to call it a switch (which directs traffic on the basis of MAC - IP mappings).
bottletop
Active Member
In general a device that sends the packets to all ports is a network hub rather than a network switch which is selective on where it sends packets (based on MAC/IP address).
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Wildebeest
Member
Indeed. So this is definitely a switch?
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Owen Smith
Well-Known Member
An ethernet hub sends the packets everywhere (except the originating port). I have some old hubs at home since they are useful for packet snooping. I'm not aware of any gigabit hubs, the last hubs made were 10/100 and even those had a switch between the 10 and 100 megabit sections.
An ethernet switch uses layer 2 ethernet frame level switching. I learns which ethernet MAC addresses can be found on which port (even if indirectly) and sends the packets to just that port. This is not IP layer switching, indeed it works with NetBIOS traffic and other non IP traffic over ethernet.
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Owen Smith
Well-Known Member
It is a gigabit ethernet switch. I can see from the traffic LEDs when speed testing my Apple TV 4K that the traffic is only going between the Apple TV port and the port to my router.
Ethernet switches know nothing about MAC - IP mappings, they work entirely in layer 2 using ethernet MAC addresses. Sure there are some managed complex switches that know about IP layers, but a basic unmanaged switch (which is most of them) knows nothing about IP.
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prpr
Well-Known Member
It doesn't, so it floods them (ethernet frames, not packets (which is a higher layer term)) to all interfaces, but from traffic received it then learns which MAC addresses are reachable on which interface, and subsequently only sends to the relevant interface. It keeps an internal (forwarding) database, which is self-ageing in the absence of relevant traffic. It also expires relevant entries if the layer 1 link dies (i.e. you unplug the cable or turn off the connected device).
It's nothing to do with IP addresses. MAC addresses only. It's a switch, which operates at layer 2. It knows nothing about IP (layer 3).
That's because there aren't any. The data rate would kill them, which is why switches supplanted hubs after 10 Mbps.
Layer 2.
Layer 2.
Those that know about MAC and IP are layer 3 switches, which perform the function of IP routers and switches at wire-speed all in one device.
You ain't gonna get one of those for £15.
Quite so. If no-one challenges it, then it happens by default, which is why it should (and must) be challenged.
Black Hole
May contain traces of nut
That sounds like quite a lot going on for £15.
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Owen Smith
Well-Known Member
Corrected. It's been 20 years since I wrote networking code and I'm a little rusty.
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Owen Smith
Well-Known Member
So this 10/100 megabit 8 port Netgear hub I'm looking at is a figment of my imagination is it? I've had it for over 20 years. It's a 10 megabit hub and a 100 megabit hub with a switch between them. Each port is connected to the hub for the speed the port negotiates at. It's great for traffic snooping since all packets are sent to every port, as I'm sure you know.
Related, if still not relevant to the original question:
Apparently you can't paste a Reddit link, or it gets rendered as
https://old.reddit.com/r/Cisco/comments/1823ceu/explain_like_im_5_spanning_tree_protocol/kag6oc9/Apparently you can't paste a Reddit link, or it gets rendered as
[media=reddit]url_path[/media] discarding the critical domain old.reddit.com.
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prpr
Well-Known Member
I didn't really say that, but I don't think I've ever seen a 100 hub. Could you post a picture at some point please, just out of curiosity? I've got a couple of old Netgear metal boxes, but I'm nowhere near them at the moment.
antipodean
Active Member
Yeah, but it probably happens inside one IC with no other chips required.
Black Hole
May contain traces of nut
Perhaps an FPGA.
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Owen Smith
Well-Known Member
Unlikely, that would be more expensive to make.
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