serial IPs

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Re: serial IPs
Easy..

/30 means 4 IP-addresses in the subnet, the first one is the network address
(wire address), the last is the broadcast address, so you can use 2
addresses. You only need two addresses, so why would you create a network
that is bigger than two adresses??



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Re: serial IPs
Hi!

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Because addresses 192.168.16.113/30 and 192.168.16.145/30 are part of
subnets 192.168.16.96/27 and 192.168.16.128/27 that are in use on other
interfaces.

Michael



Re: serial IPs
lrantisi@gmail.com wrote:
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The question is asking "the most efficient ip addressing".

Re: serial IPs

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Yes, we read that also.  I'm curious to know what your point is.

The original poster was aware that "/30" is more efficient than "/27" and
someone else has explained that the other two "/30" addresses fall within
address blocks already in use.

BernieM



Re: serial IPs
the question is not for the wan links but  for the serial interfaces.
/30 is efficient for wan links         /27 is more efficient for the
serial interfaces. .63 is the broadcast for the network and so is
wrong, .192 is the network and so is wrong therefore 192.168.16.158/27
is the oonly correct address for the serial interface.
thanks
david
BernieM wrote:
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Re: serial IPs

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How is "/27" more efficient for the serial interfaces?  It's a
point-to-point connection .. only 2 host IP addresses are required.  Why
waste a "/27" when a "/30" will do fine ... that's what being more efficient
means.

BernieM

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Re: serial IPs

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With "/30" how do you provide for the 4 host addresses needed when working
in a Frame-Relay WAN that has two "redirection" points?

The serial link is point-to-point ... only 2 host addresses are needed.

BernieM

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Re: serial IPs
the serial link could be a node or a host. if it's a node, i believe it
will be implemented with a switch, so the switch might have more than
one host, hence the requirement for a mask that provides for >2 hosts.
/30 gives you just 2 hosts. take the serial as a node and not a host
itself. nobody would implement a wan that carries just one host at the
serial lan end. wans are expensive and just a single host sounds like a
waste of money.
BernieM wrote:
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Re: serial IPs
You really need to stop reading between the lines.  It's a CCNA level
question.  Have another look at the diagram.

There is a point-to-point link between two routers.  We know they are
routers because the diagram is using the router icon.  There is no 'switch'.
Based on all the information given, remember, don't go inventing things that
just aren't there, it's simple asking what is the most efficient IP
addressing scheme for one of the serial interfaces.

Think point-to-point'.  How many host addresses do we need?  Two.  What's
the most efficient way of providing a '2 host' block?  Using a '30-bit'
mask.

Of the three 30-bit mask addresses available two fall within subnets already
in use ... leaving the correct answer being "192.168.16.193/30".

BTW .. the answer you chose is also already in use:

"192.168.16.158/27" .. has host id of '30' in the '192.168.16.128 / 27' ..
the subnet defined on the right.

BernieM

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Re: serial IPs
i advise u to read the question again. if u were given a choice from
all the objectives a - x, which would u chose for one of the serial
interfaces. the router in question has 2 serial interfaces right now
but with /27 more interfaces or hosts could be linked or connected to
the router. i wouldn't pay my network admin. for a router that's just
connect 2 computers.
BernieM wrote:
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Re: serial IPs
But the choice you made is already in use on one of the routers other
interfaces.  Which is the router in question?  What information identifies a
specific router?  The answer could be applied to either router.  Each router
only has 1 serial interface.  The other interfaces are Ethernet as depected
by the 'Ethernet' symbol.

The question isn't asking you to alllow for future growth.  The diagram
clearly shows a point-to-point link.

I'm sorry but i've already marked you paper incorrect.  Please return to
your studies.

BernieM

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