October 15, 2013
If you are going to setup a LAN with redundant paths, it is important that STP is running. If not you will be opening yourself up to these few problems
- Broadcast Storms
- MAC Table instability
- Multiple frame transmission
While the issue of broadcast storms may seem obvious, the other two may not be the things you think about at all. In the case of MAC table instability your switches will experience frequent updates to their MAC tables with wrong entires, from the looped frames which are being sent around the LAN.
The second issue of Multiple frame transmission can be somewhat, a disastrous side affect of not running STP. Duplicate copies of the looping frame can end up at the end host, in turn completely confusing it, resulting in discarded frames.
Luckily though on CISCO switches STP is on by DEFAULT
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Networking, Protocols, Switches, Troubleshoot | Tagged: broadcast storms, ccna, ccna exam, cisco, cisco switching, computer networks, frames, icnd2, icnd2 exam, it networking, mac, MAC table, networking, stp, switches | 
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Posted by Josh Gahan
October 1, 2013
The diagram below is the network in use:
Switch 3
FA0/1 – DP
FA1/1 – DP
Switch 1
FA1/1 – RP
FA0/1 DP
Switch 2
FA1/1 – RP
FA0/1 – DP
Switch 0
FA0/1 – RP
FA1/1 – ALTN
The lab for this example can be downloaded by clicking here
Leave a Comment » | ICND2 Topics, IOS Commands, Networking, Protocols, Switches, Troubleshoot | Tagged: ccna, ccna exam, cisco, cisco ios, cisco networking, cisco switches, hints n tips, icnd2, iOS, ios commands, labs, lan, Microsegmentation, networking, study, switch, switches | Permalink
Posted by Josh Gahan
April 25, 2013
All you need to know about the CSMA/CD process
- Transmitting host will listen, if silent data transmission commences
- If a voltage change is observed, (this is the collision) both hosts will send a jam signal
- This starts a random backoff algorithm, and once the random time has elapsed the host will commence transmission again by listening to the wire.
Leave a Comment » | Networking, Troubleshoot | Tagged: ccent, ccent exam, ccna exam, cisco, cisco switches, csma/cd, error, hints n tips, host, labs, listening, networking, node, packets, study, switches, TCP, UDP, voltage | Permalink
Posted by Josh Gahan
December 7, 2012
Well i decided to start creating my own labs, and since i dont have access to any physical routers/switches i decided to use GNS3 which is a great simulator of CISCO. Now what i am putting forward is my first attempt at creating a network and what i got was no ICMP echo replies from each router. Now i have rectified this fault and I’m excusing my mistake because it was 3:10 in the morning (dont ask i cant sleep) but can you spot why this network has no connectivity ?
I will post the answer within the week good luck , This shouldn’t take you too long to figure out 😀 Happy trouble shooting.
Leave a Comment » | Networking, Troubleshoot | Tagged: advice, ccent, ccent exam, ccna, ccna exam, connected routes, GNS3, hints n tips, labs, mistake, networking, questions, RIP, ripv2, static routes, study, switches | Permalink
Posted by Josh Gahan