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View Full Version : What does " cross connect " mean ?



zillah
04-11-20, 06:06 PM
Dear folk
I have been doing some research on what does cross connect mean and this is one of term that i have yet to wrap my mind around.
I would appreciate if someone in the field could explain in simple terms what exactly does it mean ? Does it have different meaning depends where it would be used ?
For instance I was searching through Ciena Optical Multiservice Edge 6500 I found this
http://imgur.com/a/x1Subhk (https://imgur.com/a/x1Subhk)
Thx

Philip
04-11-20, 08:22 PM
Just a generic term to indicate a direct connection between different servers, systems, locations, facilities, or even providers in the same building.

In data centers, for example it can be a dedicated cable between a a customer's rack and the carrier/ISP. Or a direct connection between customer A and customer B. It could be a physical connection, as in Ethernet/Fiber cable, or it can simply be a VLAN interconnect on a switch between the ports of Customer A and Customer B as well.

zillah
04-11-20, 08:51 PM
Thanks Philip

Norm
04-12-20, 10:17 AM
To add to Philips post....

I used to make crossover, or cross connect cables many moons ago. Back in those days a crossover was needed to connect two PC's (or other devices of same type) via a cat 5 cable on ethernet connections.

These links explain it well. https://www.home-network-help.com/straight.html
https://www.lifewire.com/crossover-cable-ethernet-817870
https://en.wikipedia.org/wiki/TIA/EIA-568
https://www.cctvcamerapros.com/CAT-5-Wiring-Diagram-s/293.htm
(it's all in the color coding at the each end of the cable) either a straight through or a crossover.

I believe nowadays devices have built in software to detect and apply the needed type. (not always)

zillah
04-12-20, 03:36 PM
Thx Norm

I don't think type of Ethernet cable wiring layout (Rollover , straightthrough and crossover) has something to do with the terminology cross connect

Yes there is a common word which is : cross in both terminologies crossover and cross connect but I guess it is just coincident

Norm
04-12-20, 04:28 PM
Thx Norm

I don't think type of Ethernet cable wiring layout (Rollover , straightthrough and crossover) has something to do with the terminology cross connect

Yes there is a common word which is : cross in both terminologies crossover and cross connect but I guess it is just coincident

Sorry about that. Here I am talking about apples and you're asking about oranges lol

In my little world cross connect was an established standard to link TIA-568A to TIA-568B
As the pictures in this link show - https://www.cctvcamerapros.com/CAT-5-Wiring-Diagram-s/293.htm

Maybe these links will help someone else searching for what I posted :D

zillah
04-12-20, 04:47 PM
Maybe these links will help someone else searching for what I posted
All good
Thx for sharing

By the way I have been working in DataCentre (telco companies and Business Customers ) and GSM huts belong to 3 different Telco companies for 10 years all i have been terminating is straight through and roll over for Cisco console (50m-60m) ,,,,so far I don't remember I terminated cross over cables
Do you still terminate such a connection where you work ?

Norm
04-12-20, 06:10 PM
All good
Thx for sharing

By the way I have been working in DataCentre (telco companies and Business Customers ) and GSM huts belong to 3 different Telco companies for 10 years all i have been terminating is straight through and roll over for Cisco console (50m-60m) ,,,,so far I don't remember I terminated cross over cables
Do you still terminate such a connection where you work ?

I'm retired now, but I did work for a small company installing a lot of cat5 in Catholic schools, and other Gov offices, for about a year. The only cross-over cable I ever made at the company was to connect 2 servers directly ethernet to ethernet. All the other crossovers I made were for myself or my own customers and friends. Back then they were necessary to go directly from ethernet to ethernet on 2PC's without a router or hub.
I'm not positive, but I believe the crossover is done with hardware or firmware now. The hardware can detect what type of line is attached and use what is available.

Take care, be safe out there.

Philip
04-12-20, 07:12 PM
Hi Norm :)

I believe all the Gigabit Ethernet ports now have auto-MDIX, or auto-crossover, so there is no much need for crossover cables anymore. Before with 100 Mbit ports, crossover cables were much more common. In a crossover cable simply the send and receive pairs are switched, so both ends are wired differently.

Still, when wiring a house, for example, it is important to keep all the jacks to the same standard, i.e. 586a or 586b.. There is an article on it on SG as well - https://www.speedguide.net/articles/how-to-make-network-cables-118

YeOldeStonecat
04-14-20, 07:45 AM
Yup, "crossover cables" have become extinct. Auto MDI-X is officially part of the gigabit standard. Any ethernet port that follows the gigabit standard will auto MDI-X if it detects the device on the other end of the cable requires it.
Towards the end of the fast ethernet days most of the switches and some NICs were coming out with auto MDI-X. So...after those days, those red "crossover cables" started going away, becoming unnecessary.

But Cross Connect typically refers to "direct links"....meaning links that "bypass" the usual shared connections between nodes on a network. The goal is, to have high performance direct links between those nodes...for the purposes of much faster dedicated connections between those nodes. Instead of being on shared switches "with the rest of the users" that have traffic on common uplinks.

Becoming more common these days with "cloud resources" too....have a direct link between a server cluster in "this" data center...to another server cluster in "that" data center. Combining this with "SD-WAN"...which is sort of replacing tradtiional VPN.
Instead of trying to route that traffic across the internet with all other traffic, or via traditional VPNs (which..go over the shared internet).