Router troubleshooting scenarios?
drew2000
Member Posts: 290
in CCNA & CCENT
Hey All,
I'm still lurking, the new baby (now 9 months old) hasn't completely discouraged me from chasing down ICND1 and 2, but she has made me realize how valuable time is!
The main reason I have not taken ICND 1 is that I am weak on router TROUBLESHOOTING.
Most of the other stuff I am strong enough on that if I pushed myself I could be ready for the test.
I found that Odom did a great job exposing my weakness on router troubleshooting in Chapter 15 of his ICND 1 book. His router troubleshooting scenario is excellent.
My only problem is now I know the answers.
Do you all know of any other published troubleshooting scenarios? I don't want to blindly search the web because there could be WRONG answers out there, or Brain ****.
Thanks,
Drew
I'm still lurking, the new baby (now 9 months old) hasn't completely discouraged me from chasing down ICND1 and 2, but she has made me realize how valuable time is!
The main reason I have not taken ICND 1 is that I am weak on router TROUBLESHOOTING.
Most of the other stuff I am strong enough on that if I pushed myself I could be ready for the test.
I found that Odom did a great job exposing my weakness on router troubleshooting in Chapter 15 of his ICND 1 book. His router troubleshooting scenario is excellent.
My only problem is now I know the answers.
Do you all know of any other published troubleshooting scenarios? I don't want to blindly search the web because there could be WRONG answers out there, or Brain ****.
Thanks,
Drew
Comments
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mfieldhouse
Member Posts: 41 ■■□□□□□□□□
The way I learnt, and use as a troubleshooting method is to follow the OSI model from the bottom up. I can't remember where I read it, but here's how it goes:
Layer 1: Check physical connectivity by checking the link status lights on ports, or - if you do not have physical access to the hardware, do a 'show ip int brief'. Here you will see status (layer 1) and protocol (layer 2). If at this point your status is down/down - check cabling/hardware. If this status is up/down, you have a problem at layer 2, so move onto the next layer.
Layer 2: A problem at this layer would usually be down to encapsulation, most commonly found on Serial links. Check that the encapsulation (ie HDLC, PPP etc) are the same for both links.
Layer 3: If you are confident that all connectivity up to this point is ok, then the problem usually lies with routing, ip addressing, access lists or NAT translation. Use tools such as ping and traceroute to find out which router the traffic is stopping at then check the config for each.
Troubleshooting methods may vary slightly depending on the connectivity. LAN (ethernet), PPP, ADSL etc. And there are plenty of debug commands for each.
I don't know how detailed you want to get so I'll stop here, let me know if you need anything more