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Solve : loopback address question? |
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Answer» I've been learning a bit of networking and running through tutorials, the only problem is i'm none the wiser about the loopback address. Especially when configuring routers with OSPF. All the tutorials i've gone through says "Configure OSPF on router0 with an area id of 1 and use network address 172.18.0.0/24" , no problem, i understand all that. Then it says "Configure a loopback interface on Router0 with an ip address of 10.1.27.252 255.0.0.0". Where do they get that address from?? All the examples on the internet do not EXPLAIN where the loopback addresses, that they provide, comes from. When i google it, i just get explanations about the 127.0.0.1........ i'm stumped Recently, in many areas, IP address on the Internet are now IPv6 winch specifies a long address. Have you already read some of this: http://en.wikipedia.org/wiki/IPv6 Quote The decision to put a 32-bit address space on there was the result of a year's battle among a bunch of engineers who couldn't make up their minds about 32, 128, or variable-length. And after a year of fighting, I said—I'm now at ARPA, I'm running the program, I'm paying for this stuff, I'm using American tax dollars, and I wanted some progress because we didn't know if this was going to work. So I said: OK, it's 32-bits. That's enough for an experiment; it's 4.3 billion terminations.The 32 bits are still used on a LAN. Quote from: Geek-9pm on May 14, 2012, 11:38:11 AM The 32 bits are still used on a LAN. erm, thanks? not sure what that has to do with my question though. Unless you think i'm ASKING "Where do ip addresses come from" Which, of course, i'm not. I'm asking how to work out a loopback address, because all the tutorials i've done, whether from cisco or found on the internet, never explain 'where' the address comes from they just say, "enter this address xxx.xxx.x.x as a loopback"You asked Quote ... ip address of 10.1.27.252 255.0.0.0". Where do they get that address from??What kind of answer do you want. The form 255.255.255.255 is a four byte Octet that often used to represent an ip address in IPv4 usage. I do not understand what "address xxx.xxx.x.x " means. Is that a standard notation or something you invented? Quote Octet (computing) - Wikipedia, the free encyclopedia Ar this time, 64 bits are used to program equipment IPv6 and notation now is often given in hexadecimal instead of decimal. Yes, i know what an IPv4 and IPv6 address is. I'm not after 'the origin of ip addresses' ok, In all the tutorials that i've completed, they always say things like "enter <10.10.10.1> as the loopback on router 1" or "use <12.12.12.1> as loopback on the New York router". What they do not explain IS how they come up with these addresses. It just seems as if the addresses that are given in the tutorials are being plucked out of the air. I do not see any correlation between the loopback addresses given and the, say network address etc. Now when i use Packet tracer ( a logical network simulator) to practice configuring networks and i want to configure a router with a loopback address. Where do i get this address from. How is it calculated? Yes, it would be helpful if the examples reflected what is going on in the real world. The notations used by engineers and technicians cause a lot of confusion if they are not well documented. Sorry if I am no help. Myself, I would red line that exercise and move on. It might be a type of a badly formed question. When IPv6 address are given they are not supposed to be in that kind of notation unless an explanation is provided. Quote An IPv6 address is REPRESENTED as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons [:]. An example of an IPv6 address is:It would seem your tutorial is not holding to published notations. But I am often WRONG. In the context of your question, your simply assigning a real IP address to a loopback interface. Hence 127.0.0.1 is the address of the device and 10.1.27.252 is also the address of the device. Loopback can be used as a non-physical interface - i.e. it is not used with a network or network port. It's a logical interface only.Rob Pomeroy, please note context is: Quote configuring routers with OSPFWhich is defined by Cisco for their products. http://www.webopedia.com/DidYouKnow/Computer_Science/2006/OSPF_Routing.asp But if you understand what he wants, please continue. I am totally lost! Quote from: Rob Pomeroy on May 16, 2012, 03:12:01 AM In the context of your question, your simply assigning a real IP address to a loopback interface. Hence 127.0.0.1 is the address of the device and 10.1.27.252 is also the address of the device. Loopback can be used as a non-physical interface - i.e. it is not used with a network or network port. It's a logical interface only. ok Rob, so if i wanted to configure ospf by creating a loopback, i first configure the router with an area id and network address, then do i just 'make up' a loopback address? Without seeing the tutorial you're working through, I'd struggle to guess where the 172.18.0.0/24 and 10.1.27.252/8 come from. I imagine these are within the a wider private network design. PERSONALLY, I've never had cause to use (or learn about) OSPF, so beyond answering the loopback question above, I probably can't help further, sorry. There's a good write-up here, though, which may shed some light on the use of loopback in this scenario: http://www.webopedia.com/DidYouKnow/Computer_Science/2006/OSPF_Routing.asp Cheers Rob |
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