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Home > Archive > CCNA > September 2005 > Help needed for CCNA please
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Help needed for CCNA please
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| MKRS2318 2005-08-28, 8:28 am |
| Hi all i'm new to this forum!
I need some help on a few things as i have my CCNA exam in a month.
I'm stuck on OSPF, i don't understand what a OSPF loopback is??? I don't know how a router would be assigned DR and BDR and how do you know where to assign different areas?, also what configuration settings would require you to be in privelaged mode and which in global mode? Also, what is the difference between classless IP addressing and VLSM or are they the same thing? Also i know tis might sound stupid, but what is the definition of a point to point connection exactly??
If anybody has passed the CCNA could you give me a few tips on the exam and what it is like?? Also, is it best just to do the CCNA exam or to do the two exams, the intro exam and the other one?
Thanks
Martin, A+ network+ | |
| notesadmin 2005-08-28, 10:28 am |
| Router with the highest Router ID is elected the DR, next is BDR.
ROUTER ID is given first by the highest loopback address and if it ain't any configured then highest active ip address configured on an interface makes the difference.
i consider i explained it clear enough and i also consider you lack a lot of information and you are not at all prepared for the CCNA certification exam...
Routers (Privileged Mode)is accesed with "enable" command
Routers (Global Config Mode)is accessed with "conf t" command
classless routing means exactly VLSM ! i repeat it again...don't take the exam now cose you will fail it...
good luck anyway | |
| MKRS2318 2005-08-28, 10:39 am |
| I know how to enter privelege mode and global mode, just was unsure on which one you used for various settings.
I do understand some of OSPF but, i just don't know what is meant by loopback, i know that the loopback IP address is 127.0.0.1 to test the protocol stack, just didn't know what it means in regards to OSPF. so say if you had a few routers with RID's, the highest address is elected for the DR and then the next highest for the BackupDR. Can you give it to me in idiots terms please
thanks | |
| notesadmin 2005-08-28, 11:44 am |
| you confuse the network board loopback address with a loopback interface set up on a router which is actually a virtual interface which simulates a fake 'state up' connection... | |
| MKRS2318 2005-08-28, 11:50 am |
| i know that they aren't the same thing, can you just tell me what the loopback actually does and why it is necessary??? just seems like your quoting from a book | |
| notesadmin 2005-08-30, 4:20 am |
| i don't quote from any book i just told you some things you could have easily found on google or in your ccna curriculum...
setting up a loopback interface on an ospf network will give you a certain security that the DR will remain the router you wanted from the first place!!! think about how any interface can go down when the connection fails.... | |
| notesadmin 2005-08-30, 4:23 am |
| a router is ellected DR because it's router id given by one of the ip addresses on it's interfaces is the greatest one => that interface goes down => it will be ellected a new DR ...BUT ! probably some other router that you didn't intended to let become a DR...i hope it's more clear noW !!! | |
| MKRS2318 2005-08-30, 2:18 pm |
| I'm thick, i really don't understand this. I need it in really really simple terms. Why do you need a DR and why do you need a loopback????? I understand everything out like configuring OSPF, please have patience with me | |
| johnaspen 2005-08-30, 10:05 pm |
| Hey MKRS2318, bear with me on my first boring paragraph...
Do you have the Cisco Press or Sybex CCNA book? If not, you might want to reconsider your studying strategy for this test. This baby is much more serious than the A+/Network+ you have now. Loopbacks and DR's are covered in both books along with everything else you have to know. At the same time, we are here to help so I'm glad you asked!
Notesadmin has given some very knowledgable and real world answers to your questions. I'll try to add a super-simple spin on the overall concept of "why". When a group of routers is using the OSPF routing protocol, they elect one router to be a DR and make "him" do a large portion of the "work". Since he's doing most of the work, you want to make sure the router that get's elected as the DR is one of your most powerful models (networks often have a mix of old/slow and new/fast routers). How do you force one particular router (your most powerful one) to become the DR? As notesadmin mentioned, whichever router has the highest IP address on any of it's interface will become the DR. But that leaves you with no control over who wins, so you instead assign the router that you want to be the DR a really high loopback address (does not need to start with 127.x, this is totally different from a NIC's loopback). That way the router that you want to win, will win. There's absolutely no purpose what-so-ever for that loopback (read: fake) address, other than to force the router to win the DR election.
I need to re-iterate that this explanation is extremely non-technical. Doesn't matter though as long as it helps you to start understanding! Let us know if we can help you further. | |
| MKRS2318 2005-08-31, 3:26 am |
| Thankyou Johnaspen, i get it now, why didn't the book explain it like that and then build upon that? I have got the Sybex book by Todd Lammle, it's quite good, just i didn't understand that bit about OSPF. Would you recommend that book over the one i've got?? Also i have just bought a CCNA CBT nuggets CD off ebay hopefully that will help me further, thats if it has the updated objectives. You would happen to know where i could get the latest CBT nuggets from?
I have noticed that the CCNA is a lot harder than the Network+, i think the first chapter in my CCNA study guide covers the whole Network+, however, if i hadn't done the network plus and understood the basic concepts, like the OSi model etc etc, i feel that i would not have been able to do the CCNA. Anyway, thanks for you reply. If you can think of anything else that will help me please tell me.
Thanks | |
| notesadmin 2005-08-31, 3:44 am |
| well mkrs23 i am gladd too you finally got the ideea how is done with the DR ellection in an ospf network
i've seen you're intereseted in finding the CBT training kit. i am willing to help you with that and also with some other REAL good material: TestKing, Transcender and CramMaster which are real time simulators of the ccna exam with lots of questions that were given in the real exam during the time.
leave me your e-mail address so i can reach you.
take care | |
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| johnaspen 2005-09-01, 6:14 pm |
| From another thread where notesadmin was asking for a poster's email in order to "help" him:
"there's no secret why i asked him for his e-mail address - to provide a complete training kit that he can take at 1/3 price if not less."
Of course this kind of thing should be offered as a formal advertisement through examnotes or some other board, but instead he chooses to annoy us all in forums that are meant for sharing expertise. notesadmin is the name, again that's notesadmin (be sure to view his other useful posts). I know he's cabable of making a contribution here, he just needs to shake off some bad habits. |
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