35
votes
Accepted
Why is the CAM table in a switch called CAM table and not MAC table even though it holds MAC addresses?
CAM (Content Addressable Memory) is memory that can be addressed by content, rather than a numeric memory address. You can look up the interface by presenting the memory with the MAC address. This is ...
- 100k
21
votes
Accepted
How LAN works in video games if only one station is permitted to transmit?
Only one device is allowed to transmit at any given time. At any other given time, another device is allowed to transmit.
How can you have a conversation at a dinner table if only person can speak at ...
- 759
18
votes
How LAN works in video games if only one station is permitted to transmit?
Some LAN protocols, on some media, are half duplex. That means that only one host on a LAN can send a frame at any given time. The classic example of this is the original ethernet, but the modern ...
- 100k
17
votes
IP addresses from public IP block in my LAN
EDITED
I'm assuming you're considering using an IP block that is not registered to you. Otherwise, skip to the last paragraph.
Besides being a very poor practice, if you use public addresses on your ...
- 67.9k
16
votes
Why do we need MAC Address if we can uniquely identify each machine with an IP Address
There is a historical reason for this, as @ronmaupin alludes to.
In small networks, you don't need a layer 3 protocol. All the devices are directly addressable, so layer 2 addresses work fine. As ...
- 67.9k
15
votes
Why is the CAM table in a switch called CAM table and not MAC table even though it holds MAC addresses?
CAM - Content Addressable Memory, referring to the memory used for the MAC address table.
It works kind of reverse from RAM, you address it by giving it content and it returns you the address where ...
- 1,694
12
votes
How is data sent from multiple different sources (computers) to the same destination host (computer) on a local network is handled by switch?
Switches forward all packets it receives to the best of its ability. If is unable to send a packet immediately, the packet is queued in a buffer and if the queue is full, the packet is dropped.
...
- 4,487
9
votes
Accepted
Why do we need MAC Address if we can uniquely identify each machine with an IP Address
Don't confuse the network layers. Each layer has a specific purpose. Also, don't assume that there is only one protocol for each layer. Layer-2 has many protocols, some of which use MAC addresses, and ...
- 100k
9
votes
Can Ethernet frames only be transmitted in a LAN?
No, that's not correct. You don't need a router for two hosts to communicate using IP as long as they're in the same network.
- 17.4k
9
votes
Accepted
What precisely is a link?
There is no single precise definition for a "link".
A link can be a physical layer connection, two ports connected by a cable.
A link can also be understood as general connectivity by data link ...
- 86.4k
9
votes
Accepted
Why isn't 10.0.0.0/8 used instead of 192.168.0.0/16 for private addresses?
It is merely a necessity constraint and personal preference.
If a Network is being built that would only have 10, or 20, or 50, or even 100 hosts, there is no reason not to use a /24 from 192.168.0....
- 15.1k
8
votes
Speed benefits when switching LAN from 1Gb copper to Fiber Optic
You are conflating many things here, so let's try to detangle the issues in your question.
Data rate is data rate, regardless of the physical medium. A 1Gb
connection has the same data rate whether ...
- 67.9k
8
votes
Can Ethernet frames only be transmitted in a LAN?
NO. IP packets are encapsulated inside Ethernet frames. It's not one or the other.
- 67.9k
8
votes
How do two computers with different speeds communicate
I would imagine that with TCP A will resend the packages until it's
gotten an acknowledgement for them all which would degrade A's
performance because of having to resend packages all day long (...
- 1,491
7
votes
How do two computers with different speeds communicate
With directly connected computers, both need to use the same speed when sending to each other.
Transmitting and receiving with different speeds requires splitting up the data into packets and some ...
- 86.4k
6
votes
Why do we use VLAN?
There can be many reasons to split a network into VLANs.
Security seggregation. You may want to filter or forbid communication between some systems on your networks.
Limiting of broadcast (and ...
- 13.6k
6
votes
Are there any advantages in using optic fiber to connect a host computer to an Ethernet LAN?
There's several advantages to Fiber-to-the-desk
length: copper cabling is limited to 90 meters of horizontal cabling (leaving 10 meters for patching). Fiber doesn't have this limitation. In some ...
- 19.8k
6
votes
How do two computers with different speeds communicate
In addition to the completely correct answers about speed matching directly connected systems ...
One of the fundamentals of the internet (including all the private routing portions) is that the ...
- 16.3k
6
votes
Accepted
Error Detection across OSI layers confusion
I know that in the data link layer that is responsible ensuring that
frames has been transmitted successfully by sending acknowledgement
That is incorrect. There are very few data-link protocols ...
- 100k
6
votes
Accepted
How is data sent from multiple different sources (computers) to the same destination host (computer) on a local network is handled by switch?
A switch buffers frames - this is in contrast to a repeater hub that can't buffer anything.
As @jcbermu has pointed out, both frames from A and B are first stored in their respective ports' receive ...
- 86.4k
6
votes
How does Ethernet Switch ensures the validity of the MAC address table?
Your understanding is correct, but your assumption that "no frames transmitted from either hosts, C and D." is likely wrong.
Gratuitious ARP precisely address this concern. From Wireshark.org:
The ...
- 19.8k
6
votes
How does Ethernet Switch ensures the validity of the MAC address table?
Further to JFL's answer, many devices will send gratuitous ARP when the link comes up; switches correspondingly should invalidate their MAC table for a given port when the link state changes. In your ...
- 16.3k
6
votes
Accepted
What is the difference between DHCP and NAT?
Missing from the current answers is
DHCP is a protocol for configuring hosts, and runs periodically to keep their addresses and other configuration up to date. The traffic is between the host and a ...
- 16.3k
6
votes
How Network layer routing actually works in the physical world
I want to make a few clarifications to @Effie 's answer:
The basic idea for this separation, is that each autonomous system can choose how to arrange routing within itself, however routing between ...
- 67.9k
5
votes
Accepted
Connect a LAN cable to LAN1 & LAN2
You didn't actually connect two router ports, you connected two switch ports. The router has a switch module.
You created a layer-2 broadcast storm. Broadcast is an essential part of ethernet. When a ...
- 100k
5
votes
Is it possible to set a 3 computers LAN using just cables?
It's theoretically possible if one of the computers has two network interfaces. Otherwise, how would you connect them all? But that would be a kludge at best.
If you are actually thinking about ...
- 67.9k
5
votes
Accepted
How are duplicate packets handled at the Data Link Layer?
Connection-oriented protocols are not used in "one transmitter, many receivers" scenarios, because of exactly the problem you mention. This is true not only of 802.2 Type 2, but also for IP multicast,...
- 67.9k
5
votes
Full Duplex and Collision Domain
You seem to be confused about logical topology (bus, ring, star). Ethernet has a couple of different topologies, but token ring has only the logical ring topology.
Full-duplex ethernet doesn't use ...
- 100k
5
votes
Accepted
Get MAC address of all devices (IP cameras) connected to switch
There would be a number of ways to do this that are better than the way you are currently doing it. Pick from any below that fits your circumstances and access.
If all the IP cameras communicate with ...
- 27.4k
5
votes
Do packets take the same amount of time when they are within the MTU?
I'm not completely sure what you mean.
A link will have a bandwidth. Let's assume 10 Mbps ethernet. Ethernet has some overhead: a seven octet synchronization, a one octet start-of-frame delimiter, a ...
- 100k
Only top scored, non community-wiki answers of a minimum length are eligible