33
votes
Accepted
Why are IP addresses given to each interface and not device? What would the implications of that be?
Connecting an interface to a network makes it a part of that network. Therefore, the IP address is a property of the connection, not the host.
Likewise, a host can have many network connections and ...
- 81.5k
33
votes
Accepted
What stops someone from configuring their network with IP addresses they do not own?
Most likely if they're a big university they are their own ISP, using BGP to connect their network to the internet via a number of upstream networks.
Nothing stops them from using IP addresses they ...
- 17k
29
votes
Accepted
Is multicast on the public internet possible? And if yes: How?
You cannot multicast on the public Internet, but you can multicast across the public Internet to another site by using a tunnel that supports multicast.
Multicast routing is very different from ...
- 98.3k
26
votes
Accepted
Is it common for ISPs to connect to each other directly?
Yes, this does happen quite a lot, and it is called private peering. It has some benefits over peering over an IXP:
dedicated bandwidth, you can be sure you can use the full capacity of the ...
- 17k
22
votes
Accepted
Is it possible to specify a route for a packet to take?
It's theoretically possible, but not really in a practical sense.
The IP protocol includes two options:
Loose Source and Record Route (LSRR)
Strict Source and Record Route (SSRS)
They're both ...
- 436
19
votes
Is multicast on the public internet possible? And if yes: How?
As an end-user, you cannot multicast across the Internet, unless using a tunnel.
As a larger organization, like a video provider or an ISP, it is certainly possible to forward multicast packets ...
- 590
17
votes
Why are IP addresses given to each interface and not device? What would the implications of that be?
It would not be enough.
Suppose I have a computer with three interfaces: eth0 (wired Ethernet), wlan0 (wifi), and vboxnet0 (virtualbox). One of the interfaces is connected to an internal network, one ...
14
votes
Accepted
How do routers on the backbone avoid IP address conflicts?
The RIRs assign addressing to the ISPs. An ISP not following the rules will quickly find itself ostracized and cut off from the rest of the Internet.
IANA owns the addressing and assigns each of the ...
- 98.3k
12
votes
What stops someone from configuring their network with IP addresses they do not own?
What stops them from attributing their routers and hosts already in use IP addresses?
Nothing. Over the years, I have seen both organizations of all sizes, both public and private, do this including ...
- 27.2k
11
votes
Do Bluetooth Devices have MAC address with the same specification as the MAC addresses of the Ethernet and Wi-Fi Network cards?
Bluetooth devices are required to have a unique device
address, assigned from the same registry as Ethernet and Wifi MAC addresses. Quoting the Bluetooth specification version 5.0 volume 1:
Each ...
- 243
10
votes
Accepted
Smallest IPv6 block advertised?
Yes. Nobody will advertise any network smaller than a /48. The same thing is in IPv4; no ISP will advertise any network smaller than a /24.
The problem is the sheer number of routes that would ...
- 98.3k
10
votes
Accepted
How are IPv4 Addresses provided uniquely to domains?
Who mainly provides IP addresses to domains? As in, who commands, "www.google.com, 103.233.38.93 is yours; www.stackexchange.com I will assign 104.16.115.182 to you; etc."
Normally IP addresses are ...
- 13k
10
votes
What are the differences in the contents of datagrams, frames, and network packets?
The terms Frame, Packet, and Segment exist to create abstractions from what one layer is responsible for verses the others.
To explain that, and to answer your question thoroughly, I'm going to start ...
- 14.8k
10
votes
Accepted
Analyze Network Traffic by Autonomous System Number?
You can certainly do this with Wireshark.
In the menu choose Statistics > Endpoints and you will see a window like this:
You might need to copy and paste into Excel to sum the bytes per AS, or use ...
- 16.1k
10
votes
Why are IP addresses given to each interface and not device? What would the implications of that be?
A device that has an IP address exists within a network.
A Router is a device who's primary purpose is to pass traffic between networks.
For a Router to pass packets between two networks, it must ...
- 14.8k
9
votes
Accepted
Finding Subnet Ranges of IPv6
Basically, with IPv6, most subnets will just be /64. Using subnets of other sizes, with a couple of exceptions, will break features of IPv6. See RFC 5375, IPv6 Unicast Address Assignment ...
- 98.3k
9
votes
Accepted
What's the domain of an IP?
It is a routing domain. That is a block of addressing controlled by a single entity. For example, Company X could be assigned 10.11.0.0/23, Company Y could be assigned 10.11.2.0/23, and Company Z ...
- 98.3k
9
votes
Accepted
Is it true that the fd00::/8 address range (ULA) in ipv6 is for machines that you NEVER want to speak with anything on the Internet?
IPv6 packets addressed in the IPv6 ULA address range, fc00::/7, can not be routed on the public Internet. Remember, though, that interfaces can have multiple IPv6 addresses, including Link-Local, ...
- 98.3k
9
votes
Accepted
Is QoS an issue for VOIP calls over the Internet? If not, why not?
VoIP over the public Internet can be a problem, but it usually works good enough, most of the time, although there can be times where it sucks. Most ISPs have extra cost features where they will honor ...
- 98.3k
8
votes
using fiberoptic for long-distance ethernet connection
Part 1: Using fiber to run a 1000 foot ethernet link
Using fiber to run a long ethernet link is not quite as simple as you make out but it's certainly not unreasonable to DIY.
A few things you have ...
- 13k
8
votes
Accepted
Private IP inside internet?
Traceroute deliberately sends packets with low time-to-live values to make the routers between you and your destination send back ICMP TTL exceeded messages. The traceroute output is basically the ...
- 4,670
8
votes
Accepted
Why is the internet *not free?
Most ISPs have to buy service from other ISPs to be able to reach every part of the internet. That is called "transit". If you start a small ISP you usually buy transit from one or more bigger ISPs. ...
- 6,680
8
votes
Accepted
When X.25 or ATM were used in ISP networks or Internet backbone was the protocol running over this layer still TCP/IP?
Think of it this way: we used the fastest links we could buy to run IP over the wide area between the nodes of the Internet. So that was 56/48Kbps X.25, and later 1.44/2Mbps Frame Relay, and later ...
- 1,171
8
votes
Accepted
Class A most significant bits '0' as in RFC1166 or older or '00' as suggested in RFC4632?
It appears to be a typo in that RFC. Notice that the header of the RFC says Errata Exist. It is not uncommon for things like that to happen.
That particular error is corrected in the errata. See the ...
- 98.3k
8
votes
What are the differences in the contents of datagrams, frames, and network packets?
Note:
the term datagram is used in various ways. If we stick to RFC1594 a datagram is
A self-contained, independent entity of data carrying
sufficient information to be routed from the source
to the ...
- 19.4k
8
votes
Is QoS an issue for VOIP calls over the Internet? If not, why not?
I'm trying to decide whether I should buy SIP trunks from my ISP or a 3rd-party.
and...
Is QoS an issue for VOIP calls over the Internet?
Short answer:
End-to-end QoS is NOT offered on the public ...
- 29.9k
8
votes
What stops someone from configuring their network with IP addresses they do not own?
Nothing will stop them using the addresses on their own machines.
What happens if they try to advertise them to the Internet depends on how sloppy their providers are. If their providers are ...
- 13k
8
votes
Is a point-to-point T1 line literally a line in real life?
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 ...
- 66.9k
8
votes
Accepted
In practice, how are BGP Advertisement destinations determined and configured?
Some connection between the two ISPs is needed. Dedicated fibers (for example in a datacenter they're both present in) is very common. But there are other possibilities: a layer 2 connection (for ...
- 17k
7
votes
Accepted
PPPoE interface doesn't use ARP
PPP doesn't use MAC addresses or ARP the way ethernet does, so no, there will not be ARP in PPP, but there may be ARP in the ethernet which carries the PPP frames. You will not see anything ethernet-...
- 98.3k
Only top scored, non community-wiki answers of a minimum length are eligible