Stuck with CCENT/CCNA specifially cabling

sys_teck

Hi, guys

Currently, I am working on my CCENT/CCNA. But I am stuck on cabling specifically straight-through, crossover, and rollover cables, specifically pins numbers and positions and their connection to PC's <servers>, Routers, switches, hubs.

My sources: Wendell Odom Official Cert Guide ICND1 100-101
Cisco website: cisco learning network.

Can you recommend additions sources where would cleared explanation about cabling and pin<s> positions related to connection to different devices.

thanks

bbarrick

CCENT is fairly straightforward, especially in the 100-101 book.

Just remember that a cable going from PC, Router or Wireless Access Point device to either a Switch or a Hub tends to be a straight through cable.

The reason being is that the PC, Router, and WAP transmits on wire 1 and wire 2 which is typically the orange/white wire(1) and orange wire(2).

Then the PC, Router, and WAP receive data on wires 3 and 6 which is typically the green/white wire(3) and green wire(6).

So the pinout most people use when running a wire from a PC to a Switch is a straight through pinout. o/w, o, g/w, bl, bl/w, g, br/w, b.

When crimping an RJ/45 as a straight through that is the typical lineup on both ends of the wire.

So since a PC transmits on 1 and 2 and receives on 3 and 6, you can't hook up two PC's with a straight through cable. You have to use a crossover.

A crossover has the same pinout on one end as the straight through, o/w, o, g/w, bl, bl/w, g, br/w, b.

But when connecting two PC's the other end is all that changes. 1(o/w) must now connect to 3 and 2(0) connects to 6.

So the crossover cable would look something like this: [o/w, o, g/w, bl, bl/w, g, br/w, b]

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[g/w, g, o/w, bl, bl/w, o, br/w, br]

The only thing I"M going to bother to remember, speaking for test purposes, is which devices require a straight through between them and which devices require crossover.

I've got the pinouts memorized pretty much for a straight through, the crossover I usually have to glance at just to refresh my memory though.

theodoxa

Like devices tend to require crossover, while unlike devices use straight-through. The easiest way to remember is how devices are normally connected - Router --> Switch --> PC. Router --> Switch and Switch --> PC would both use straight-through cables. OTOH, if you wanted to connect like-devices such as 2 switches, 2 routers, or 2 PCs directly you would use a crossover cable. For the purposes of cabling you can just think of a Hub and a Switch as the same.

I believe at one time [before there was Cisco] routers were just servers programmed to perform routing. Most servers can still do this. MS Windows Server has RRAS (Routing and Remote Access Services), which although it makes a really sh***y router does support Static Routing, RIPv2, [I believe OSPF]. Their site-to-site VPN feature sucked and would frequently disconnect for no reason and/or refuse to reconnect. Linux also has a number of distros that are made for routing. Routers and PCs/Servers are like devices and require a crossover cable.

As for the pinouts, I memorized TIA/EIA-568B and then just remembered University of Miami colors - Flip the Orange (Pins 1 and 2) and Green (Pins 3 and 5) pairs - to make a crossover. You won't be tested on it for CCNA, but if you use any WIC-1DSU-T1 modules, its worth remembering University of Florida, Auburn, or some other team with the same colors - Flip the Orange (Pins 1 and 2) and Blue (Pins 4 and 5) pairs when making a T1 Crossover cable (used to connect 2 x T1 ports together).

iamme4eva

theodoxa - it's 1&2, 3&6. Not 3&5.

I've no idea why I remember, probably just because I've done it so long, but I just remember that 3 and 6 are split, and all the other colours are together. It alternates colour/white then colour.

o/w, o, g/w, bl, bl/w, g, br/w, br.

As for the connections, just remember the like devices rule, and remember that switches / hubs (which are the same thing regarding cabling) are the "odd one out". Anything connecting to a switch (except another switch) is a straight through. Anything else is a crossover.

theodoxa

iamme4eva wrote: »

theodoxa - it's 1&2, 3&6. Not 3&5.

You're right. I must've miscounted as I only memorized the colors not the pin numbers. Strangely, Odom's ICND1 Book focuses heavily on the numbers but barely mentions the colors.

sys_teck

Thank you guys @bbarick, theodoxa, and iamme4eva