Windows 7 Forums

Welcome to Windows 7 Forums. Our forum is dedicated to helping you find support and solutions for any problems regarding your Windows 7 PC be it Dell, HP, Acer, Asus or a custom build. We also provide an extensive Windows 7 tutorial section that covers a wide range of tips and tricks.


Windows 7: Internetwork Troubleshooting Guide

01 Feb 2010   #10
Barman58

Windows 10 Pro x64 x2 Windows 10 Enterprise x64, Ubuntu
 
 

What we have to remember here is that the OSI model is exactly that - a model. A physical piece of equipment can span more than one layer in the model, so a router can exist in both the physical and data link layers


My System SpecsSystem Spec
.
01 Feb 2010   #11
aem

Windows 7 Ultimate 64Bit
 
 

The teaching of networking will be best left to the experts. I'm like yourself know what we know, from what we read here and there so if i am wrong, then i am wrong lol.

Ok, lets see how far i can go....

Quote:
What if the router's NIC broken down (worn out over time), how exactly can I describe it? A layer 3 device broke? The fact that it's routing capability is still there, just the interface is ruined. How exactly can we "trace" the problem if not from "lower layers" of that device?
You wouldn't say a Layer 3 "device" broke plainly like that. Routers work off Layer 3 protocols. Each layer is connected to one another logically and information must travel through each layer down the order untill it reaches the physical layer where it then leaves your machine and heads towards the physical router. The information will go from the machine's interface port onto the medium (cable) to the router's interfact port. If say a ping of the router fails, the data packet will know this and it will either cease to exist or back track. Information then goes in reverse back to your machine, through the same interface, and up the layers. You won't know that a ping has failed untill the information reaches a layer that processes this information. Such activities when you break it down, might seem long, but in computer terms is can be as quick as a flash. When the machine gives you the info that a ping has failed, say host unreachable or request time out, you would then know that the ping has failed, and it failed not at physical level, but at a network level. Obviously if a ping fails at a network level (logical level) there is a good chance there might be something wrong with the router or an interface of the router, as the physical level.
My System SpecsSystem Spec
01 Feb 2010   #12
aem

Windows 7 Ultimate 64Bit
 
 

Each machine work off the OSI model with protocols inter-linking from layer to layer on the machine. Information travels from Layer 7 down to Layer 2's logical link layer, and when it reahes the MAC layer of Layer 2, this is when logical becomes physical.

A router is a device/hardware seperate to the machine. Information goes from the machine to the router "physically" (thru a medium, and yes as hard as it may sounds wireless is also a form of physical connection) but the informatin of say a ping failure gets processed at the network layer. This is why the router is known to be a layer 3 device, as much as a hardware.
My System SpecsSystem Spec
01 Feb 2010   #13
zzz2496

Windows7 Ultimate 64bit
 
 

Quote   Quote: Originally Posted by aem View Post
The teaching of networking will be best left to the experts. I'm like yourself know what we know, from what we read here and there so if i am wrong, then i am wrong lol.

Ok, lets see how far i can go....

Quote:
What if the router's NIC broken down (worn out over time), how exactly can I describe it? A layer 3 device broke? The fact that it's routing capability is still there, just the interface is ruined. How exactly can we "trace" the problem if not from "lower layers" of that device?
You wouldn't say a Layer 3 "device" broke plainly like that. Routers work off Layer 3 protocols. Each layer is connected to one another logically and information must travel through each layer down the order untill it reaches the physical layer where it then leaves your machine and heads towards the physical router. The information will go from the machine's interface port onto the medium (cable) to the router's interfact port. If say a ping of the router fails, the data packet will know this and it will either cease to exist or back track. Information then goes in reverse back to your machine, through the same interface, and up the layers. You won't know that a ping has failed untill the information reaches a layer that processes this information. Such activities when you break it down, might seem long, but in computer terms is can be as quick as a flash. When the machine gives you the info that a ping has failed, say host unreachable or request time out, you would then know that the ping has failed, and it failed not at physical level, but at a network level. Obviously if a ping fails at a network level (logical level) there is a good chance there might be something wrong with the router or an interface of the router, as the physical level.
In my days in Cisco training lab (it was 2002/2003 iirc), when I encounter such problem I'm told to (according to my teacher's words) "trace from lower layers upward", this by his definition is make sure what you can touch, plug, etc is up and running, no diagnostic LED blinking, check cables, switch cables if you're in doubt, check that the plug is not loose, replug if loose, etc. This "trick" helped me in my 6 professional years as "All around network handyman".

I won't even start to guess "maybe it's driver, maybe it's X, maybe it's Y, maybe it's Z"... I'll start from the bottom (make sure the connectors are tight, LED indicator light up, etc), then go up (check ARP, ping, recheck ARP), then after that check the IP (ping), after that check the layer 4 (make sure that the ports are open and is listening to requests), and so on...

This is my "way" of doing things, I'm sorry if my way of thinking is not "in harmony" with yours .

zzz2496
My System SpecsSystem Spec
.

01 Feb 2010   #14
aem

Windows 7 Ultimate 64Bit
 
 

The test case is all well except you might want to put in a Media Access Control Layer as part of the Data Link Later, at this half of Layer 2, it's where you talk about the adapters. The physical Layer 1, is where you say something like make sure you have the correct cable and it's inserted properly. It's up to you but for a non tech person that not necessary i don't think.
My System SpecsSystem Spec
01 Feb 2010   #15
zzz2496

Windows7 Ultimate 64bit
 
 

Quote   Quote: Originally Posted by aem View Post
Each machine work off the OSI model with protocols inter-linking from layer to layer on the machine. Information travels from Layer 7 down to Layer 2's logical link layer, and when it reahes the MAC layer of Layer 2, this is when logical becomes physical.

A router is a device/hardware seperate to the machine. Information goes from the machine to the router "physically" (thru a medium, and yes as hard as it may sounds wireless is also a form of physical connection) but the informatin of say a ping failure gets processed at the network layer. This is why the router is known to be a layer 3 device, as much as a hardware.
In my mind, when I experience ping failure, I instinctively will start from checking physical connections (in my word ==> "physical layer"), going up to second layer (MAC address, check this with ARP command), and so on... This way I know in what "layer" it fails and then act accordingly. I don't quite care about guessing why a ping command fails, it's irrelevant... I'll just trace it, by the time I arrive at layer 3(IP), most of the time I already know what the culprit was...

Note: In my days, I use many other link layer (layer 2) protocols other than Ethernet/MAC, I once setup Frame Relay connection (that's a Layer 2) using several Cisco routers over serial connection (thick heavy duty cables, Cisco proprietary), and it uses HDLC frames, at layer 3 uses IP. Another time I got a client that's running over microwave, I forgot what the Link layer protocol was... At that time, if I were think as if this network stack is one huge complicated mess, troubleshooting a failed ping will take days, even weeks... . That will definitely get my arse fired...

zzz2496
My System SpecsSystem Spec
01 Feb 2010   #16
zzz2496

Windows7 Ultimate 64bit
 
 

We are commenting each other's post in minutes intervals...

zzz2496
My System SpecsSystem Spec
05 May 2010   #17
CarlTR6

Windows 7 Ultimate 32 bit
 
 

ZZZ, this is outstanding work!
My System SpecsSystem Spec
05 May 2010   #18
zzz2496

Windows7 Ultimate 64bit
 
 

After reading this guide, I suggest you read the other one...

zzz2496
My System SpecsSystem Spec
05 May 2010   #19
CarlTR6

Windows 7 Ultimate 32 bit
 
 

I did! And is is excellent, too. I repped you on that one. Unfortunately, I can't rep you again.
My System SpecsSystem Spec
Reply

 Internetwork Troubleshooting Guide




Thread Tools




Similar help and support threads
Thread Forum
Internet Troubleshooting Guide
Dinesh's Complete Internet Troubleshooting Guide This is your one-stop internet related issues guide. Here I will show you some ways to fix your high speed or dial up internet connection issues with Windows 7.I will show you some very useful and basic steps that you can follow without having...
Tutorials
Windows Media Player Troubleshooting Guide
Windows 7 has some fine in-built diagnostic tools to help you troubleshoot Windows Media Player issues, which you may be facing. This tutorial will give you some steps to fix common problem you might encounter with Windows Media Player 12.The N and KN editions of Windows 7 have all the features...
Tutorials
troubleshooting
Troubleshooting used to work but now it doesn’t. How can I fix the error message that says an error occurred while troubleshooting.
Performance & Maintenance
Outlook - General Troubleshooting Guide for Issues
General Troubleshooting Guide For Issues with Microsoft Outlook These are some General troubleshooting steps to fix Outlook issues like unable to open or crashing while doing something in Outlook etc. 1. Start up problem of Outlook This is one of the most common problems with...
Tutorials


Our Sites

Site Links

About Us

Find Us

Windows 7 Forums is an independent web site and has not been authorized, sponsored, or otherwise approved by Microsoft Corporation. "Windows 7" and related materials are trademarks of Microsoft Corp.

© Designer Media Ltd

All times are GMT -5. The time now is 05:58.
Twitter Facebook Google+ Seven Forums iOS App Seven Forums Android App