Really nice explanation!!
I'm an IT teacher myself and sometimes it's really hard to explain this to
students... i think I'll use your mail...
cheers
Pedro
On Friday 17 October 2008 18:08:21 Mike Knisely wrote:
> First, I'm happy to hear you're going through the Cisco Academy. I am a
> graduate of that program and have been an instructor for that curriculum at a
> local state college. I think that it is an excellent foundation no matter
> what your IT focus is in the future and would encourage anyone in the IT
> field to get the first semester book at a minimum. An IT knowledge built on
> the OSI model (or even TCP/IP model) will do wonders for your troubleshooting
> skills.
>
> Next, 16 is not a gateway... 16 in the last octet would be the network
> number. Network number and Gateway are not the same thing. A gateway is the
> IP address, from the useable pool of addresses, assigned to another router in
> that network. All devices that have interfaces should have the same first
> three octets and the last octet should be a value between (and including)
> 17-30. Each interface should also have the subnet mask 255.255.255.240.
> Assuming that the 28-bit mask is correct, anything other than 255.255.255.240
> for the mask is wrong... not saying it won't work, but it's wrong.
>
> For a basic example, lets look at this in the good ol' 192.168.1.0
> 255.255.255.0 space, common to practically every home-class broadband router
> available. When you unbox the thing, it is configured with an ip address of
> 192.168.1.1 on it's LAN interface. You would then use that IP address as
> your "gateway" setting on any internal device. 192.168.1.0 (the network
> number) isn't typed as a setting anywhere, because it is a mathematical
> result of "anding" an IP address and the mask. So, if your PC is
> 192.168.1.10 on this network and your mask is 255.255.255.0 let's "and" them.
>
> 192.168.1.10 = 11000000.10101000.00000001.00001010
> 255.255.255.0 = 11111111.11111111.11111111.00000000
> anding result = 11000000.10101000.00000001.00000000
>
> So, we convert that back to decimal and we get 192.168.1.0... Our network
> number!
>
> Your original post says that you entered .16 as the "gateway ip" in Endian.
> That tells me that you have told Endian it needs to go to a router at
> 88.255.199.16 to get to the Internet. Now that we know that 16 is a network
> number and not a useable IP address on this network, we see that it
> definitely is not the correct setting for this field.
>
> Whomever is giving your a connection to the outside world, probably the same
> entity that told you to use this address space, should be able to tell you
> which of your pool of addresses is the correct IP to use as your gateway.
>
> Mike K.
>
> ________________________________
>
> From: ozgurerdogan [mailto:[EMAIL PROTECTED]
> Sent: Fri 10/17/2008 03:54
> To: efw-user@lists.sourceforge.net
> Subject: Re: [Efw-user] Entering correct subnet mask stops connection?
>
>
>
>
> Thats exatcly what I meant Mike Knisely. I am a CCNA student and I know all
> what you explained. So I have 16-31 and my netmask would be 255.255.255.240
> and 16 is my gateway (network ID) and 31 is my broadcast ip and I use only
> 17-30 ip inside network.
>
> I do not remember why I entered 31 as netmask but at the moment it is
> running so. Maybe my datacenter did something in router so I can not enter
> 240, I will call them today. But by entering 240, I think I am doing correct
> settings right?
>
> Thank you very much.
> --
> View this message in context:
> http://www.nabble.com/Entering-correct-subnet-mask-stops-connection--tp20015603p20028158.html
> Sent from the efw-user mailing list archive at Nabble.com.
>
>
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--
----------------------------------------------------------------------------------------------------------
Pedro Oliveira
IT Consultant
Email: [EMAIL PROTECTED]
URL: http://pedro.linux-geex.com
Telefone: +351 96 5867227
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