alt.certification.network-plus - A couple of basic questions

Author

A couple of basic questions

Steve Cline

2003-05-22, 6:24 pm

Greetings all,

Recently A+ certified, studying for Network+...not a lot of hands-on
experience, so if these questions seem a little amateurish, you know why:

I'm using the Mike Meyer's All-in-one (worked great for A+)

1) On a basic LAN (I'm only on Chap 6)...I understand that a sending node
sends frames/packets to all nodes within the collision domain...but does it
send a copy to itself? The source of the question deals with collisions.
The way it's explained in the book, the sending node compares what it sent
to what it receives (p. 94) and if it's different it considers it a
collision. But, it seems implied that it's expecting to receive a copy of
what it sent? Is that the case?

2) Something that wasn't really explained having to do with 10base5/RG-8
LAN: If the segment can be 500 meters long, with spacing every 2.5 meters,
why is it limited to 100 nodes? Why isn't it 200?

3) Also, dealing with 10base5: I understand a break in the segment will
bring down the LAN due to reflection issues, but will that also occur if the
break is in the drop cable? I don't think so, but it isn't stated.

See....I told you they were pretty basic. I am looking for answers beyond
"that's just the way it is" but I also understand that
sometimes.....well....that's just the way it is. I also know that some or
all of this may be outside the scope of the test, but I'm just asking
because I'm curious. The test/certification is secondary to the
knowledge...I have a job, don't need to boost my resume. I appreciate any
and all input.

Thanks

Steve

PS. This is a great NG...some good info on here

turretjam

2003-05-22, 6:24 pm

I can only answer questions #1 I'm pressed for time!

1. No, when it refers to comparing what it sent to what it receives, it's
the accepting node that actually does the comparing, and that's of the CRC,
if that mathematical equation turns up wrong, then the receiving nodes asks
the sending computer for that particular packet back. Perhaps what you have
is worded a little fuzzy, that happens sometimes and can be confusing

Cheers

"Steve Cline" <steve.a.cline@worldnet.att.net> wrote in message
news:V9cza.168182$ja4.8397030@bgtnsc05-news.ops.worldnet.att.net...
> Greetings all,
>
> Recently A+ certified, studying for Network+...not a lot of hands-on
> experience, so if these questions seem a little amateurish, you know why:
>
> I'm using the Mike Meyer's All-in-one (worked great for A+)
>
> 1) On a basic LAN (I'm only on Chap 6)...I understand that a sending node
> sends frames/packets to all nodes within the collision domain...but does
it
> send a copy to itself? The source of the question deals with collisions.
> The way it's explained in the book, the sending node compares what it sent
> to what it receives (p. 94) and if it's different it considers it a
> collision. But, it seems implied that it's expecting to receive a copy of
> what it sent? Is that the case?
>
> 2) Something that wasn't really explained having to do with 10base5/RG-8
> LAN: If the segment can be 500 meters long, with spacing every 2.5
meters,
> why is it limited to 100 nodes? Why isn't it 200?
>
> 3) Also, dealing with 10base5: I understand a break in the segment will
> bring down the LAN due to reflection issues, but will that also occur if
the
> break is in the drop cable? I don't think so, but it isn't stated.
>
> See....I told you they were pretty basic. I am looking for answers beyond
> "that's just the way it is" but I also understand that
> sometimes.....well....that's just the way it is. I also know that some or
> all of this may be outside the scope of the test, but I'm just asking
> because I'm curious. The test/certification is secondary to the
> knowledge...I have a job, don't need to boost my resume. I appreciate any
> and all input.
>
> Thanks
>
> Steve
>
> PS. This is a great NG...some good info on here
>
>

jumbojim12345REMOVETHIS@lycos.com

2003-05-23, 2:24 am

On Thu, 22 May 2003 22:28:05 GMT, "Steve Cline"
<steve.a.cline@worldnet.att.net> wrote:

>Greetings all,
>
>Recently A+ certified, studying for Network+...not a lot of hands-on
>experience, so if these questions seem a little amateurish, you know why:
>
>I'm using the Mike Meyer's All-in-one (worked great for A+)
>
>1) On a basic LAN (I'm only on Chap 6)...I understand that a sending node
>sends frames/packets to all nodes within the collision domain...but does it
>send a copy to itself? The source of the question deals with collisions.
>The way it's explained in the book, the sending node compares what it sent
>to what it receives (p. 94) and if it's different it considers it a
>collision. But, it seems implied that it's expecting to receive a copy of
>what it sent? Is that the case?
>
>2) Something that wasn't really explained having to do with 10base5/RG-8
>LAN: If the segment can be 500 meters long, with spacing every 2.5 meters,
>why is it limited to 100 nodes? Why isn't it 200?

Can't quote you a link but believe it is a timing issue; as with the
length issue with 10baseT not over 100 meters.

>
>3) Also, dealing with 10base5: I understand a break in the segment will
>bring down the LAN due to reflection issues, but will that also occur if the
>break is in the drop cable? I don't think so, but it isn't stated.

Only if the break is in the thicknet, going from the thicknet to the
ethernet card is different cable.

see diagram:
http://www.ethermanage.com/ethernet...2.html#HEADING1

~dan

>
>See....I told you they were pretty basic. I am looking for answers beyond
>"that's just the way it is" but I also understand that
>sometimes.....well....that's just the way it is. I also know that some or
>all of this may be outside the scope of the test, but I'm just asking
>because I'm curious. The test/certification is secondary to the
>knowledge...I have a job, don't need to boost my resume. I appreciate any
>and all input.
>
>Thanks
>
>Steve
>
>PS. This is a great NG...some good info on here
>

Crazymiclo30

2003-05-23, 9:24 am

"Steve Cline" <steve.a.cline@worldnet.att.net> wrote in message
news:V9cza.168182$ja4.8397030@bgtnsc05-news.ops.worldnet.att.net...
> Greetings all,
>
> Recently A+ certified, studying for Network+...not a lot of hands-on
> experience, so if these questions seem a little amateurish, you know why:
>
> I'm using the Mike Meyer's All-in-one (worked great for A+)
>
> 1) On a basic LAN (I'm only on Chap 6)...I understand that a sending node
> sends frames/packets to all nodes within the collision domain...but does
it
> send a copy to itself? The source of the question deals with collisions.
> The way it's explained in the book, the sending node compares what it sent
> to what it receives (p. 94) and if it's different it considers it a
> collision. But, it seems implied that it's expecting to receive a copy of
> what it sent? Is that the case?

The checking is done by the receiving system with the CRC.
>
> 2) Something that wasn't really explained having to do with 10base5/RG-8
> LAN: If the segment can be 500 meters long, with spacing every 2.5
meters,
> why is it limited to 100 nodes? Why isn't it 200?
Too many collisions will occur if there are more than 100 nodes. It lets
you know that you can place them at 2.5 meters but if you go over 500 meters
there is too much attenuation. The signal will fail. Basically you can
place them 2.5 meters from each other. And you can have 2 computers 500
meters from each other.
>
> 3) Also, dealing with 10base5: I understand a break in the segment will
> bring down the LAN due to reflection issues, but will that also occur if
the
> break is in the drop cable? I don't think so, but it isn't stated.
>
I don't remember for sure but i don't think so either.

> See....I told you they were pretty basic. I am looking for answers beyond
> "that's just the way it is" but I also understand that
> sometimes.....well....that's just the way it is. I also know that some or
> all of this may be outside the scope of the test, but I'm just asking
> because I'm curious. The test/certification is secondary to the
> knowledge...I have a job, don't need to boost my resume. I appreciate any
> and all input.
>
> Thanks
>
> Steve
>
> PS. This is a great NG...some good info on here
>
>

Charles M. Kozierok

2003-05-23, 9:24 am

In article <V9cza.168182$ja4.8397030@bgtnsc05-news.ops.worldnet.att.net>,
Steve Cline <steve.a.cline@worldnet.att.net> wrote:
} 1) On a basic LAN (I'm only on Chap 6)...I understand that a sending node
} sends frames/packets to all nodes within the collision domain...but does it
} send a copy to itself? The source of the question deals with collisions.
} The way it's explained in the book, the sending node compares what it sent
} to what it receives (p. 94) and if it's different it considers it a
} collision. But, it seems implied that it's expecting to receive a copy of
} what it sent? Is that the case?

The matter of collision detection actually depends on what type of LAN
you are talking about.

For a bus LAN like 10BASE2 or 10BASE5, there is a single shared wire.
The transmitter starts sending on the wire and everything on the wire hears
it, almost like how anyone can pick up a phone in the same house and
hear a conversation. Collisions are detected by looking for an
interference pattern on the wire (to oversimplify things.)

For a star LAN like 10BASE-T, detection is different. Each device sends
on one wire pair and receives on another. If they are connected by a
hub, the device transmits and the hub takes the signal and sends it to
each other device on those devices' receive pairs. If another device
transmits at the same time, device A will receive a signal from device B
while it is transmitting and will know a collision has occurred --
because device C will be getting stuff from device A and device B at the
same time.

} 2) Something that wasn't really explained having to do with 10base5/RG-8
} LAN: If the segment can be 500 meters long, with spacing every 2.5 meters,
} why is it limited to 100 nodes? Why isn't it 200?

It's not related to the length of the cable. It's just what the
specification says is the limit. They had to set some sort of limit to
allow other design decisions to be made.

If you want a better answer to this, try posting to comp.dcom.lans.ethernet
-- lots of really good techies there, including Rich Seifert, who was
one of the guys who wrote the specs!

} 3) Also, dealing with 10base5: I understand a break in the segment will
} bring down the LAN due to reflection issues, but will that also occur if the
} break is in the drop cable? I don't think so, but it isn't stated.

A break in the main cable causes the LAN to come down because it is
shared by all devices. The drop cables are really a separate link
completely and do not affect the main cable.

peace,

-*-
charles

Steve Cline

2003-05-24, 9:24 am

Thanks all. I think that clears up everything. Expect to hear back from
me as I trudge through the book!

I hope I'm not getting too "wrapped around the axle" on this. I just get
into this a little too much sometimes.

Thanks again

Steve

"Steve Cline" <steve.a.cline@worldnet.att.net> wrote in message
news:V9cza.168182$ja4.8397030@bgtnsc05-news.ops.worldnet.att.net...
> Greetings all,
>
> Recently A+ certified, studying for Network+...not a lot of hands-on
> experience, so if these questions seem a little amateurish, you know why:
>
> I'm using the Mike Meyer's All-in-one (worked great for A+)
>
> 1) On a basic LAN (I'm only on Chap 6)...I understand that a sending node
> sends frames/packets to all nodes within the collision domain...but does
it
> send a copy to itself? The source of the question deals with collisions.
> The way it's explained in the book, the sending node compares what it sent
> to what it receives (p. 94) and if it's different it considers it a
> collision. But, it seems implied that it's expecting to receive a copy of
> what it sent? Is that the case?
>
> 2) Something that wasn't really explained having to do with 10base5/RG-8
> LAN: If the segment can be 500 meters long, with spacing every 2.5
meters,
> why is it limited to 100 nodes? Why isn't it 200?
>
> 3) Also, dealing with 10base5: I understand a break in the segment will
> bring down the LAN due to reflection issues, but will that also occur if
the
> break is in the drop cable? I don't think so, but it isn't stated.
>
> See....I told you they were pretty basic. I am looking for answers beyond
> "that's just the way it is" but I also understand that
> sometimes.....well....that's just the way it is. I also know that some or
> all of this may be outside the scope of the test, but I'm just asking
> because I'm curious. The test/certification is secondary to the
> knowledge...I have a job, don't need to boost my resume. I appreciate any
> and all input.
>
> Thanks
>
> Steve
>
> PS. This is a great NG...some good info on here
>
>

dan

2003-05-25, 9:24 pm

Steve, Get wrapped around that axel....To truly understand a process
is having the answer to a thousand questions. Why is it doing this?
Why does it have to be this way. Why not that?

To not just be answering questions rotely but to understand why is
true knowledge.

*steps off soap box*

~dan

On Sat, 24 May 2003 13:55:48 GMT, "Steve Cline"
<steve.a.cline@worldnet.att.net> wrote:

>Thanks all. I think that clears up everything. Expect to hear back from
>me as I trudge through the book!
>
>I hope I'm not getting too "wrapped around the axle" on this. I just get
>into this a little too much sometimes.
>
>
>Thanks again
>
>Steve
>
>
>
>
>"Steve Cline" <steve.a.cline@worldnet.att.net> wrote in message
>news:V9cza.168182$ja4.8397030@bgtnsc05-news.ops.worldnet.att.net...
>> Greetings all,
>>
>> Recently A+ certified, studying for Network+...not a lot of hands-on
>> experience, so if these questions seem a little amateurish, you know why:
>>
>> I'm using the Mike Meyer's All-in-one (worked great for A+)
>>
>> 1) On a basic LAN (I'm only on Chap 6)...I understand that a sending node
>> sends frames/packets to all nodes within the collision domain...but does
>it
>> send a copy to itself? The source of the question deals with collisions.
>> The way it's explained in the book, the sending node compares what it sent
>> to what it receives (p. 94) and if it's different it considers it a
>> collision. But, it seems implied that it's expecting to receive a copy of
>> what it sent? Is that the case?
>>
>> 2) Something that wasn't really explained having to do with 10base5/RG-8
>> LAN: If the segment can be 500 meters long, with spacing every 2.5
>meters,
>> why is it limited to 100 nodes? Why isn't it 200?
>>
>> 3) Also, dealing with 10base5: I understand a break in the segment will
>> bring down the LAN due to reflection issues, but will that also occur if
>the
>> break is in the drop cable? I don't think so, but it isn't stated.
>>
>> See....I told you they were pretty basic. I am looking for answers beyond
>> "that's just the way it is" but I also understand that
>> sometimes.....well....that's just the way it is. I also know that some or
>> all of this may be outside the scope of the test, but I'm just asking
>> because I'm curious. The test/certification is secondary to the
>> knowledge...I have a job, don't need to boost my resume. I appreciate any
>> and all input.
>>
>> Thanks
>>
>> Steve
>>
>> PS. This is a great NG...some good info on here
>>
>>
>

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