Questions tagged [layer1]

For questions about the OSI layer-1 (physical layer).

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5
votes
3answers
8k views

The maximum length of CAT6 for intranet network?

Recently I purchased CAT6 cable with a length of 150 meter. I bought another CAT6 with a length of 148 meter. I joined both the cables using RJ45 cable coupler. I tested it using LAN TESTER, and ...
8
votes
3answers
15k views

Why do I need a crossover cable to connect devices of the same type?

I know that a crossover cable should be used to directly connect devices of the same type and patch cable is used to connect devices of different types. But I never understood why is it so exactly? ...
19
votes
4answers
83k views

Cable Colors and Purpose

I've been doing some work with some big businesses and so far I've learned yellow is internet and blue is phone. Is this a standard or is this just a personal chose? Do colors mean different tasks?
13
votes
5answers
3k views

How exactly does an Ethernet collision happen in the cable, since nodes use different circuits for Tx and Rx?

I am trying to understand how a collision occurs in Ethernet, especially when a duplex mismatch exists or when on a legacy Ethernet network two nodes transmit simultaneously. Everyone explains the ...
15
votes
5answers
89k views

What's the difference between an Ethernet cable and a UTP cable?

Is there such a thing as an Ethernet cable or technically no? Are they actually called UTP cables? From wikipedia UTP cables are found in many Ethernet networks and telephone systems.
15
votes
6answers
8k views

Reason for half-duplex mode in Ethernet?

Half-duplex connections were popular at the time of 10Mbps and 100Mbps Ethernet, and, according to standards, it is allowed also in case of 1Gbps Ethernet. Am I correct that half-duplex mode support ...
5
votes
4answers
12k views

what is the difference between a CSU/DSU and a modem?

I'm so confused, both do the same function, converting the analog to digital, but what's the difference?
7
votes
2answers
448 views

What certifications are there for Fiber Optic termination and splicing?

As a knowledgeable person in computer networks I have always had an itch for learning how to create custom-length fiber optic cables. So, as a personal goal, I want to get trained and certified in ...
8
votes
3answers
2k views

Running Cat 7 STP cables in the same cable trays as 3-phase power cables

I am doing some work in a factory that is quite new, and have been asked to terminate some network cables - simple enough. However on looking up at the cable trays, which are suspended from the ...
7
votes
6answers
12k views

Can a single optical fiber support full-duplex communication?

Can a single-mode single optical fiber support full-duplex communication, or does it have to be two fibers, one for each direction?
5
votes
2answers
943 views

How does a router know the MTU of a network?

I've done several exercises where you're given the MTU of a net or subnet, but I wonder how routers know the MTU of the nets they're connected. I've learnt that in OSPF protocol this information is ...
4
votes
3answers
529 views

What practices/ mechanisms/ protocols can be used to secure communication on physically exposed Ethernet links?

Given that Ethernet cables are everywhere and use for all kinds of links and it is assumed they are physically guarded, hence typical installations do not leverage any "secure" mechanisms. Let's say ...
3
votes
2answers
254 views

Cat6 FTP shielding

I received a edexcel patch panel for a cat6 ftp cable, I was puzzled by the diagram. It shows I should cut away the foil. I am used to pulling the foil back and placing it under the bar clamp. Is it ...
2
votes
3answers
7k views

How to create Ethernet cables when I cannot figure out color of cat 5e cable wires?

I'm learning how to make my own Ethernet cables (to get deep understanding of Cisco for their exams), but the cables I am getting have small wires whose colors I cannot distinguish. A person in my ...
1
vote
1answer
201 views

Connecting a router with cat 5 cable to a cat 7 network

I have a cat 7 network but the router, switch and APs are hooked up to it using cat 5 cables. Does this reduce the advantages of a cat 7 network?