Post #67,538
12/9/02 11:51:47 AM
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Thoughts on That
1) You can have an interface with multiple IP addresses *on the same network*, provided they all look the same when the netmask is applied.
2) You cannot have the same interface on two physically different networks. Each connection to a separate physical network needs a separate physical interface. See below.
3) The proper solution to your issue is to install a second NIC and attach that to the other network.
About 2) - let's say you're on one physical network configured as 192.168.1.0 mask 255.255.255.0, but for some perverse reason you set up two computers on this physical network with 192.168.2.0 addresses. Will they talk to each other? Most likely not - the switch will see IP packets with the wrong net address and drop them, if not complain more bitterly to the admin. A properly configured network only passes packets with the correct network address and mask for the segment they live on.
If you need to divide a single segment, you use subnet mask ranges - like this:
For our imaginary 192.168.1.0 network, we could set up various machines with varying masks 255.255.255.X - for example, to divide it in two:
1st mask 255.255.255.00001111 2nd mask 255.255.255.11110000
This divides the segment into address ranges 192.168.1.1-127 and 192.168.1.128-255. Machines on each logical segment can now happily and independently coexist with a switch having mask 255.255.255.0.
-drl
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Post #67,586
12/9/02 2:12:21 PM
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Reading between the lines
Think laptop. Connect to one network with one profile. Move to new site, connect to network with another profile. etc...
Thanks, Peter. I just picked up a laptop to take with me while working on client sites. (Always can find a drop, but never a computer.) And each client has different network configurations. This way I can create a hw profile for each client, and access their system without a problem.
CRC, is this what you are trying to do? Or single computer with access to multiple lans via a single connection?
[link|mailto:jbrabeck@attbi.com|Joe]
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Post #67,602
12/9/02 3:08:35 PM
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Re: Reading between the lines
?
DHCP servers assign IP addresses and masks on any reasonable network.
-drl
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Post #67,607
12/9/02 3:18:31 PM
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Oh hush.
Many small networks are staticly assigned.
Peter [link|http://www.debian.org|Shill For Hire] [link|http://www.kuro5hin.org|There is no K5 Cabal] [link|http://guildenstern.dyndns.org|Blog]
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Post #67,617
12/9/02 3:54:55 PM
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Aha!
The Great [link|/forums/render/user?username=pwhysall|BOFH] among us said: Many small networks are staticly assigned. Some Extremely Large Networks are staticly assigned, also! Ain't that right [link|/forums/render/user?username=static|Wade]? (PUN intended!)
[link|mailto:curley95@attbi.com|greg] - Grand-Master Artist in IT [link|http://www.iwethey.org/ed_curry/|REMEMBER ED CURRY!!!]
Your friendly Geheime Staatspolizei reminds: [link|http://www.wired.com/news/wireless/0,1382,56742,00.html|Wi-Fi enabled device use] comes with an all inclusive free trip to the (county)Photographer! Overbooking, is a problem, please be prepared for "room-ies".
Why You ask? Here is the answer to your query: SELECT * FROM politicians WHERE iq > 40 OR \\ WHERE ego < 1048575; 0 rows found
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Post #67,748
12/10/02 1:57:01 AM
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You rang?
gfolkert intoned: The Great [link|/forums/render/user?username=pwhysall|BOFH] among us said:Many small networks are staticly assigned. Some Extremely Large Networks are staticly assigned, also! Ain't that right [link|/forums/render/user?username=static|Wade]? (PUN intended!) I wasn't going to get in the way of CRC's static address situation. He seemed perfectly able of going round in circles without my help. Besides, I wouldn't want to damage anything there... That said, even large networks are likely to have a few statically assigned IP addresses in amongst the seas of DHCPed ones. Servers. Gateways. Certain Clients. If you have a decent IP address management structure for the amount of change it experiences, it is possible for Very Large networks to not use DHCP. I've seen this in action. That said, I use static IPs on my machines at home. Wade.
"Ah. One of the difficult questions."
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Post #67,770
12/10/02 9:12:45 AM
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Yeah...
I was really stretching on the "Static" part... but you did confirm my point for me Sir... Danke.
Me Personally, I use Static for all of my inplace machines at home... but still have a DHCP server running for those "Throw-ins" fer LAN Parties and such.
Dam I gotta Quit getting "New" to me machines... I just got another Pentium-200 (going to be my new FW).
Oh well...
[link|mailto:curley95@attbi.com|greg] - Grand-Master Artist in IT [link|http://www.iwethey.org/ed_curry/|REMEMBER ED CURRY!!!]
Your friendly Geheime Staatspolizei reminds: [link|http://www.wired.com/news/wireless/0,1382,56742,00.html|Wi-Fi enabled device use] comes with an all inclusive free trip to the (county)Photographer! Overbooking, is a problem, please be prepared for "room-ies".
Why You ask? Here is the answer to your query: SELECT * FROM politicians WHERE iq > 40 OR \\ WHERE ego < 1048575; 0 rows found
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Post #68,214
12/11/02 5:10:08 PM
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Yup, that's it exactly. (Wasn't that *obvious* to everyone?)
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Post #67,593
12/9/02 2:31:53 PM
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Windows does not particularly like
Out of Bit order Subnet Masking. It gets confused sometimes. Well, most of the time you run them concurrently.
Running a SNM of 255.255.255.240 is just fine Windows won't have a cow on this one. But 255.255.255.16... Yikes it'll screw up the XOR if the same interface has the other active SNM active also.
Only time I use OOBSNM is when I am short on available IP Ranges, and I have to get places connected using those. Most of the time I just use a 255.255.255.252 (or 4 address routing network). I rather use a variable length subnet mask than an out of bit order one. Less headache and doesn't go against the CIDR stuff(big, Big, BIG) out there.
All int all, OOBSNMs are not a truly supported option in most of the Older Routers and Switches out there. It'll confuse them as well. BE careful where you use it.
[link|mailto:curley95@attbi.com|greg] - Grand-Master Artist in IT [link|http://www.iwethey.org/ed_curry/|REMEMBER ED CURRY!!!]
Your friendly Geheime Staatspolizei reminds: [link|http://www.wired.com/news/wireless/0,1382,56742,00.html|Wi-Fi enabled device use] comes with an all inclusive free trip to the (county)Photographer! Overbooking, is a problem, please be prepared for "room-ies".
Why You ask? Here is the answer to your query: SELECT * FROM politicians WHERE iq > 40 OR \\ WHERE ego < 1048575; 0 rows found
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Post #67,604
12/9/02 3:10:55 PM
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Correct
I was just giving illustrative examples. This issue with netmasks is often not well explained.
-drl
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Post #67,651
12/9/02 6:41:37 PM
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Might be interested to know... (new thread)
Created as new thread #67650 titled [link|/forums/render/content/show?contentid=67650|Might be interested to know...]
[link|mailto:curley95@attbi.com|greg] - Grand-Master Artist in IT [link|http://www.iwethey.org/ed_curry/|REMEMBER ED CURRY!!!]
Your friendly Geheime Staatspolizei reminds: [link|http://www.wired.com/news/wireless/0,1382,56742,00.html|Wi-Fi enabled device use] comes with an all inclusive free trip to the (county)Photographer! Overbooking, is a problem, please be prepared for "room-ies".
Why You ask? Here is the answer to your query: SELECT * FROM politicians WHERE iq > 40 OR \\ WHERE ego < 1048575; 0 rows found
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Post #68,213
12/11/02 5:07:18 PM
12/11/02 5:08:29 PM
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Unfortunately...
This issue with netmasks is often not well explained. ...I still couldn't say that it is. (Not that it matters very much, since it seems rather irrelevant to my situation.)
Christian R. Conrad Mechanisation As our souls are slowly stolen The wheels of progress keep steamrolling Mechanisation melts our minds To drive the furnace that drives us blind. -- [link|http://www.vergenet.net/~conrad/poetry/mechanisation.html|© Conrad Parker, 1993]
Edited by CRConrad
Dec. 11, 2002, 05:08:29 PM EST
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Post #68,226
12/11/02 5:32:21 PM
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Sorry, but Peter's right - you Just Don't Get It.
Ross offers some advice: 1) You can have an interface with multiple IP addresses *on the same network*, provided they all look the same when the netmask is applied. That's great... I think -- or, probably *would* think, if I were a network engineer or something such, so I cared deeply about such issues. But what in the world gave you the impression that I do? 2) You cannot have the same interface on two physically different networks. Each connection to a separate physical network needs a separate physical interface. See below. Oh, *that* must be why all the other consultants are toting around laptops with thirty-eight network cards in them -- one for each LAN they ever attach to! No, hold on, wait a minute... Hey, guess what -- they *don't*! 3) The proper solution to your issue is to install a second NIC and attach that to the other network. Yeah, right... Maybe if I wanted to attach to several different networks *at the same time* -- but where did I ever say I wanted to do that? (And are *you* going to pull a network cable from my home to wherever I go to work each morning, so I can be on my home network while I'm at the office...?) About 2) - let's say you're on one physical network configured as 192.168.1.0 mask 255.255.255.0, but for some perverse reason you set up two computers on this physical network with 192.168.2.0 addresses. [...] imaginary 192.168.1.0 network, we could set up various machines with varying masks 255.255.255.X - [...] This divides the segment into address ranges 192.168.1.1-127 and 192.168.1.128-255. [...] En ymmärä tuosta juuri mitään, mutta se ei haita, kun ei oikein koske minun tilannettani. Mahtasitko tietää että tuo kaikki oli minulle yhtä hepreaa? Luultavasti et, kun aina vain oletat olevasi oikeassa, vaikka puhuisit jostain ihan muuta kun kaikki muut keskustelussa osallistuvat. There, that was probably just as enlightening to you as your gobbledygook was to me... Thanks, Ross, but no thanks. Peter's really right: You should actually *read* the question before you spout off the answer to something else.
Christian R. Conrad Mechanisation As our souls are slowly stolen The wheels of progress keep steamrolling Mechanisation melts our minds To drive the furnace that drives us blind. -- [link|http://www.vergenet.net/~conrad/poetry/mechanisation.html|© Conrad Parker, 1993]
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Post #68,244
12/11/02 7:38:09 PM
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I think... therefore I might just understand...
En ymm\ufffdr\ufffd tuosta juuri mit\ufffd\ufffdn, mutta se ei haita, kun ei oikein koske minun tilannettani. Mahtasitko tiet\ufffd\ufffd ett\ufffd tuo kaikki oli minulle yht\ufffd hepreaa? Luultavasti et, kun aina vain oletat olevasi oikeassa, vaikka puhuisit jostain ihan muuta kun kaikki muut keskustelussa osallistuvat. --->Greg Speak - Trying to read Finnish, and trying to paraphrase.<--- Dam those creative solutions to problems, while it's not my inconvenience , it doesn't really concern me "something I believe means 'BABY'". Would you speak to me just as well in Hebrew? Presumably you would/could and while never merely really understanding, although we are debating as to why the Glorious one is actually participating. --->End Translation of Gobbledegook<--- I was introduced to Finnish as a read language in the Marine Corps... never really did anything with it till just now.
[link|mailto:curley95@attbi.com|greg] - Grand-Master Artist in IT [link|http://www.iwethey.org/ed_curry/|REMEMBER ED CURRY!!!]
Your friendly Geheime Staatspolizei reminds: [link|http://www.wired.com/news/wireless/0,1382,56742,00.html|Wi-Fi enabled device use] comes with an all inclusive free trip to the (county)Photographer! Overbooking, is a problem, please be prepared for "room-ies".
Why You ask? Here is the answer to your query: SELECT * FROM politicians WHERE iq > 40 OR \\ WHERE ego < 1048575; 0 rows found
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Post #68,278
12/11/02 10:04:07 PM
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Re: Sorry, but Peter's right - you Just Don't Get It.
Oh, *that* must be why all the other consultants are toting around laptops with thirty-eight network cards in them -- one for each LAN they ever attach to! No, hold on, wait a minute... Hey, guess what -- they *don't*!
I would not do what is being suggested here, and I doubt that any of the consultants you see wandering around do it. Any client with enough infrastructure to need a consultant will have a DHCP server that sets all that stuff up on the fly. It's the very same principle as dialing up to the Internet over the phone lines. You tell the network "I'm here" and it gives you an IP address, a network to live on, and a gateway to the rest of the world.
I was at IBM - people had several machines, laptops, labs, etc. Issues like this never arose as people went from room to room to experimental setup to lab to conference etc. It is so easy to configure a DHCP server that any network with more than say 8 nodes should use it. If you ever had a real need to reconfigure your personal network settings from the ground up, then that is the responsibility of the client in any case.
-drl
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Post #68,292
12/11/02 10:50:28 PM
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I know of several companies
one with over 750 staff and 1k computers have static addressing. It depends on how you want to configure a net. If each port is labelled with an ip address and mask the task is fairly simple. DHCP has its uses in dialup and net on demand but static tables also work quite well. From a secure standpoint I would hesitate to see conslutants dragginf their own boxen in and leaving with the contents daily. Make me nervous that would. thanx, bill
will work for cash and other incentives [link|http://home.tampabay.rr.com/boxley/resume/Resume.html|skill set]
Opera was the television of the nineteenth century:loud, vulgar and garish with plots that could only be called infantile. "Pendergast"
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