The Reason We Can't Use The Mac Address As The Only Address For The Whole Internet Is ____________9/27/2019
The MAC address might be unique, but there's nothing special about the number that would indicate where it is. MAC 00-00-00-00-00-00 might be on the other side of the planet from 00-00-00-00-00-01. IP is an arbitrary numbering scheme imposed in a hierarchical fashion on a group of computers to logically distinguish them as a group (that's what a subnet is). Sending messages between those groups is done by routing tables, themselves divided into multiple levels so that we don't have to keep track of every single subnet. For instance, 17.x.x.x is within the Apple network.
Think of a MAC address as a description of a house on your street. To your neighbors, they will all understand 'The green house' or 'Mr. Johnsons house' or 'The duplex on the corner' -- These are comparable to a MAC address, descriptive only locally. MAC address is the basis on which communication occurs.However we need IP address to be able to create a routing table,that enables faster commnication.Lots of communication algorithms take use of IP address ( Network address +SubNet masks) to be able to route packages faster.
From there, Apple will know where each of its thousands of subnets are located and how to get to them (nobody else needs to know this information, they just need to know that 17.anything goes to Apple). It's also pretty easy to relate this to another pair of systems. You have a State Issued ID Number, why would you need a mailing address if that ID number is already unique to just you? You need the mailing address because it's an arbitrary system that describes where the unique destination for communications to you should go. This is a great answer.
I would have added that MAC addresses are ultimately used in IP communications once the computers determine they're on the same subnet; that's why ARP poisoning works as an attack. The same thing with a default gateway, the computer addresses packets destined for another subnet to the MAC address returned by the ARP lookup for the default gateway IP. Layer-3 / IP addressing is mostly used by routers and only used by the host to determine if the destination is on the same subnet. – Jul 24 '12 at 13:38.
@ChrisS I have a friend who as a sys admin, received a batch of cards from a single vendor and the cards only had one MAC address in the entire palette. The vendor said that the cards did not get mixed in to the retail distribution correctly so that there were duplicates, since the order was a direct drop from the factory.
Before the cards went to retail distribution, they were supposed to get mixed together to spread the dupes around. So for a given vendor, MAC addressees aren't unique, much less across vendors.
– Jul 24 '12 at 15:09. Because the routing tables would become impossibly large. IP addresses are allocated hierarchically, so a router can group routes by address prefixes. The number of autonomous systems present on the net now is reasonable enough to fit in today's hardware. On the other hand, the distribition of MAC addresses across the network is random and completely unrelated to topology.
Routes grouping would be impossible, every router would need to keep track of routes for every single device that relays traffic trough it. That is what layer 2 switches do, and that does not scale well beyond a certain number of hosts. Take a look at the OSI model: This explains why it doesn't make sense to make routing, a layer 3 concept, decisions based on a physical, layer 2, mechanism. Modern networking is broken into many different layers to accomplish your end to end communication.
Your network card (what is addressed by the mac address physical address) needs to only be responsible for communicating with peers on it's physical network. The communication that you are allowed to accomplish with your MAC address is going to be limited to other devices that reside within physical contact to your machine. On the internet, for example, you are not physically connected to each machine. That's why we make use of TCP/IP (a layer 3, logical address) mechanism when we need to communicate with a machine that we are not physically connected to. Routing tables for MAC addresses would need almost every single device with a MAC address listed.
Routing to the Internet for IP is a single entry 0.0.0.0/0. For networks classes they break down as 10.0.0.0/8 172.16.0.0/16 and 192.168.0.0/24. Many of these can be aggregated like 172.16.0.0/12 and 192.168.0.0/16 further reducing the routing table size. Routes are searched in reverse order in to the number of one bits in their mask. This makes routing to 192.168.100.0/24 work when there is a route for 192.168.0.0/16 and another for 0.0.0.0/0 (default route). EDIT: Originally, the IP range was broken into several classes; A, B, and C being the most significant.
The A class made up the first half of the address range, the B range the next quarter, and the C range the next eight of the range. These classes had masks of 8, 16, and 24 bits respectively. Later the strict usage of these masks was dropped and address allocation were done in a variety of sizes. The size of the allocation is always a power of 2 and the lowest and highest address in each allocation are reserved. Each allocation will also have an address for a router. This is often the lowest or highest non-reserved address.
The smallest practical allocation is a /30 address. IPv6 uses the same form of allocation with a /64 the smallest allocation that can appear on the Internet. Typically, and ISP will be given much larger allocation, which is all the Internet routers would need to know about. Expected allocations are specified in the RFCs.
The ISP would need to know how to route its own subnet, and what addresses to route to which interconnect routers. This is significantly simpler than knowing how to route each mac address. I think the main point they're trying to put across is that MAC addresses are determined by vendors, so there is no coherent addressing scheme that could be adhered to in a local subnet due to the huge variety of manufacturers that make interfaces. MAC addresses are used when the destination address is in the local subnet (192.168.0.x, for example). When traffic does not match the local subnet, the computer refers to the routing table. Generally the routing table will tell any traffic that does not match the local subnet (0.0.0.0) to head to the local gateway, at which point any affiliation to MAC addresses are stripped entirely. The only way MAC addresses could be used globally would be to have one, huge, flat subnet, which would be wholly unworkable.
Hey everyone, We have a Dell laptop here that will not connect to the internet using an unsecured open WIFI network that we need for other people to use. My laptop/phone/ipod will connect to this but this dell will not.
We have noticed that it had software on there (preinstalled by intel) called fraud protected, we assumed this could be blocking the internet connection but after uninstalling this software it still doesn't work. It seems the laptop doesn't connect to the DHCP server to get an IP. IP config spits out that it doesn't have an IP address. We have tried giving the laptop a static IP and also tried 'IPCONFIG /reset' and 'IPCONFIG /renew' both didn't fix it. Windows firewall being disabled didn't help. Any advice would be great. Maybe this is related- maybe not.
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I was at a hotel where I logged into wifi with my phone. I have data on my phone, so I was connected to the Internet without it. When I logged into the hotel wifi, the wifi symbol came up which was good.
My iPad only works with wifi (no data). When I got out my iPad and connected to the hotel wifi, I did not see the ID and PW requirement, but the wifi symbol appeared so I thought I was connected. However, when I tried to connect to the Internet the feedback note was 'Could not connect to a secure server' which I believe is the same issue presented above. When I eventually wrote in my ID and PW I was able to use the Internet without problem even though the wifi symbol had appeared the whole time so I thought I was connected the whole time. I just saw this thread and had to share.
I'm attending a community college and everyone I spoke to did not have a problem connecting with their laptops. My phone did connect, though. I realized the url my phone used to connect after putting in the login info was different than the one I was redirected to on my laptop which said the server was insecure. So, I tried using the phone's url on the laptop and I then had access to the server.
I still get a message saying the server is insecure, but it still connects me. Don't know if this helps any.
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