Hot answers tagged

5

Short answer: no, an ONT is no modem. Modem is short for MOdulator/DEModulator and is only used for three device classes: telephone modems, DSL modems, and cable modems (thx Cody). These modulate digital data on to voice-grade phone lines or (possibly former) television cable. DSL and cable "modems" often include a router, but technically these are routers ...


5

In the 1990s in a British regional ISP, we had a choice from the telephone company of getting two settings for multiple lines: In the ordinary hunt group, the next incoming call would arrive on the lowest unused line on the group In the rotary hunt group, the next incoming call would hunt from the last position for the next unused line of the group The ...


5

From the HOWTO you linked: rotary dial in set of telephone lines When I wore a younger man's clothes, back in the late 1990ies, I ran a bunch of Shiva LAN Rovers (in their IBM guise labelled as IBM 8235). In short, they were essentially a 1RU box with a LAN interface (our first ones had Token Ring, of course!) and 8 slots for modems or ISDN BRI adapter ...


5

Almost all consumer Internet access links use only a single IP address and many business links as well. A single IP address can't be shared directly but extremely commonly (source) NAT is used. A modem per se can't be shared but when a connection is dialed up by a router and then NATted, the connection can be shared just with xDSL, fiber or anything else. ...


4

JFL was correct it was a NIC checksum offloading error. My guess is that when my virtual router was behind my physical router it somehow made it so it didn't need to do checksumming. Recap of Problem: Scenario A: virtual behind physical resulted in 88mbps (pfsense 2.4.2 as a KVMguest on CentOS 7 with default settings on the pfsense install.) (...


3

The particular device you have listed is required to be used as a pair. This is for someone who want to extend a network across voice cabling, or for a small ISP to use to connect to customers. It doesn't work as a general replacement for a DSL modem. This is explained in the device description (my emphasis): The VC-231 provides CPE and CO mode for ...


3

Fundamentally a circuit is needed to convert the stream of data packets from the internal form used inside the device into a form suitable for tranmission over the physical medium in use. Whether that device is called a "modem" varies between different physical layers. The convention seems to be that the term "modem" is used when communicating across a ...


3

Modems are only needed to translate signals between analog and digital circuits. Some devices called modems aren't really modems in the strictest sense. For instance, many variants of ethernet use copper, but ethernet uses digital signals, and you wouldn't call a device which connects to a copper circuit using ethernet a modem, although I know people who do. ...


3

In the 1980s, most of the dial-up connections I saw were UUCP, not IP. Our server would call the various other servers and exchange mail and files. In this way it most certainly was for more than one user. By the early 1990s, I saw a lot of corporate networks where there was a dial-up modem making a conventional IP link, with mostly sendmail SMTP traffic ...


2

It depends on the type of VPN technology used and if IPSec is used for authentication and encryption and then what type of encryption and data integrity you use with IPSec. I know AH can bypass NATs and ESP can't. But when you say modem bridged to router with VPN, are you referring to a single device with a "modem"/WAN interface and LAN (or LAN and WLAN ...


2

The computer connected to the modem would start one PPP (or earlier, SLIP) session, and it would get one IP address from the ISP. So yes, one connection for every dial-up connection. There were methods to "share" this with other computers on the same LAN (similar to what we do with Hotspots today). Of course the speeds would be so low that more than one ...


1

An ONT has some sort of modem inside, as the box people normally call a modem does. I mean, modem is short for modulator-demodulator, that is, something that takes a digital signal and modulates into an analog one, and demodulates an analog signal to convert it into digital stream of 0s and 1s In the case of the ONT the analog signal it's modulated light, ...


1

CSU/DSU is usually only used to refer to T-carrier lines, dubbed digital signal. T-carrier lines use Alternate Mark Inversion line codes. Basically, there are just two symbols - mark and space - at a high baudrate, requiring high-frequency cables. xDSL is a family of broadband modulation schemes using discrete multi-tone modulation (DMT) or more ...


1

ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 ipv6 route ::/0 FastEthernet0/0 Never do that. That's proxy-arp. Too many people do that with zero clue what it actually means... that's not a dialup interface that needs to be forced up. router ospf 99 Who are you exchanging routes with? You don't need OSPF running. And for that matter, you don't need to have all ...


1

Shielded cable does not perform as well as unshielded cable if it is not properly grounded, and the shield will actually create problems by reflecting internal signals back into the cable. Unshielded cable should work correctly if you have more than 6" of separation from the power lines (probably a legal requirement, anyway). You may have an electrical ...


1

This is basic routing, a function that normally routers perform by default, without any special configuration other than setting the IP addresses on the interfaces. Assuming the ISP take care of routing the 4 public IP addresses to your router, all you have to do is set the IP addresses on the servers and the router, and configure the router with whatever ...


1

Apparently, you are overthinking this. With a PBX you get as many PSTN lines as necessary for the total number of simultaneous PSTN calls that you may have. Usually, you get a DID range that is larger than the number PSTN of lines. You could have a single incoming PSTN line, but separate numbers in a DID range for each internal function. The PBX can then ...


1

You can do outbound routing to specific destination with static routes. You can prefer one of ISPs for particular site inbound with BGP and your own PI pool. You can do advanced routing decision with some L4-L7 technologies, for instance, Cisco PfR. Though I can't see a good way to reroute through another ISP after connection to remote site is established, ...


1

Because "business class" implies use in many situations where the service may be supplied by something other than ADSL. Combined router/modems are pretty much a home/consumer niche device. Getting your signal via DOCSIS cable? ADSL is useless to you. Got a Fiber line? - ADSL is useless to you. Got an ethernet feed from a provider in your office building? ...


1

A DSL or DOCSIS modem is a specialized bridging device. Including one in a router is either a cheap gimmick or increases the expense of a business device that will limit its adoption. Spring for the ADSL2+ modem and you will both probably never have to replace it and will have every option under the sun for routers.


1

A router transfers packets between two (or more) different networks. A typical case is a router sitting between the home or office network and the ISP's network. A more complex case might have several separate LANs, a separate VoIP network, multiple ISP connections and several VPNs. There are cases where the ISP provides a connection which is directly ...


Only top voted, non community-wiki answers of a minimum length are eligible