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7

Literally? No. Unless the devices were very close, it's very unlikely they would ever have been directly connected. Even 20-30 years ago, in the era of T1's, there were repeaters, digital cross-connects, and multiplexing into larger T-carriers. As Ron has said, today the T1 is a relic. It will be emulated and carried as packets like every thing else "...


8

No. There may be a dedicated circuit between the routers and the nearest telco central office, but between offices they are switched and multiplexed onto other, higher capacity circuits. Today, most T1 circuits are emulated over a packet-switched (IP) network. They are rapidly becoming obsolete, and are being replaced by SIP over the IP network.


1

Yes, most often. It depends on how exactly your ISP connects your IP addresses into their network. Usually, you're given a subnet where one IP address is used by their router - e.g. 192.0.2.32/28 with the router on .33, and .34 through .46 for you to use. You can then connect a firewall and map those addresses into your network, but you can just as well ...


1

(This will tread on "historical trivia") The tiered construct was the original vision of the ARPANet (what became the internet.) The modern internet does not work like that. In fact, the early internet -- and ARPANet before it -- didn't entirely work like that either. With the advent of BGP, any network could be anywhere, connected to anyone. ...


4

There's not really a hierarchy. It's really more of a web. There are national (or international) ISPs that connect to a large number of other ISPs. There are smaller ISPs that connect to only a few other ISPs. Then there are large companies that have their own backbone (Google, Microsoft, Amazon, Facebook, etc). There's no "rule" about who can ...


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