Implementing Cisco IP Routing (642-902 ROUTE) Tutorials
IPv6 / IPv6 Addressing pt. 2
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Subtitles of the Movie (Implementing Cisco IP Routing (642-902 ROUTE) / IPv6 / IPv6 Addressing pt. 2)
So let's carry on discussing IPv6 addressing. The Routing Prefix is the first 48 bits, we covered that at the tail end of the previous video. The Subnet ID is next up and it is 16 bits long and this is where individual administrators whether they're network administrators at companies or within the ISP can say these Subnets are assigned to these routers and they can break it down inside their own routing domain. The rest of the IP address, the other 64 bits reserved for the Host address and the Host again, doesn't have to take all 64 of those, we'll get into how that's determined in the next slide. So there are some IPv6 address types that we need to go over. The first is called a Global Unicast Address. This is basically a public IP address if you have a Global Unicast Address then you should be reachable anywhere on the Internet by that IP address. These start with 2000 and they have three bits reserved as the Global Unicast Prefix. So basically if you see an IPv6 address that starts with 2000, then you know it's a Global Unicast Address, it's out there on the Internet and anybody should be able to get to these addresses. Now they're used to be a set of addresses called Unique Local or Site Local Addresses and these were basically private IP addresses that network administrators could use to uniquely identify their own little private networks and they weren't routable on the Internet and everything and this is where PAT and NAT came in. You could NAT IPv6 Unique Local to Global Unicast Addresses. Since the IPv6 working group wants to do away with NAT, they did away with Unique Local and Site Local addresses. Now I mean I suppose technically you could still use Unique Local or Site Local addresses but they're not officially supported in the RFCs for IPv6 any longer. The last IP Address Type or IPv6 Address Type we'll talk about is a Link Local Address. There's not really an analog to Link Local addresses in IPv4. Link Local addresses are local to the link, they're Link Local addresses, I don't really know of a better to describe them. Routers don't forward these Link Local addresses, they're to uniquely identify a Host on a particular network segment. Hosts can calculate their own Local Link addresses and we'll get into that here in the next slide I believe and these Link Local addresses come from the range FE80 and the first ten bits are reserved for that. So it's FE80 and there's two or three zeros that follow that. I, I used to be able calculate it off the top of my head but I'm, I'm not that good anymore. So we'll see these Link Local and Global Unicast Addresses in our lab. Once we assign addresses, we'll see how the Link Local address gets automatically calculated on our routers. So enough of the Prefixes. What about the last 64 bits of the IP address? We have a MAC address that's 48 bits long yet it's somehow uniquely identifies the machine in IPv6. Well how does that 48 bit address get stuffed into a 64-bit address space? Well this last 64 bits is called the Interface ID. It can be anything so long as it is Globally Unique and Global Unique I, I probably used the wrong word there. So long as it's unique, Globally Unique on that segment. Although I suppose if you have a Global Unicast Address it does need to be unique in the entire world. At any rate the last 64 bits are generally calculated from the MAC address of the network interface that you're dealing with. So for all intents and purposes they are unique. Basically IPv6 splits the MAC address in half and inserts FFFE in the middle of it to spread out that 48 bit address into a 64-bit address. It sets the seventh bit of the MAC address to a one, so it's not exactly like the MAC address and, and I'll give you an example here whenever we get done with a slide. For example, if the MAC address is that there, I won't read it all out, then the IPv6 Link Local Address would FE80::9644 you see how it added a one here in this bit position so it translated this four to a six. 9644:52FF:FEBC:1BFE. Now this format is called the EUI 64 format. In point, Unique Interface 64-bit format. Now as an example, I'm recording this video on Windows XP, I know it's a twelve year old operating system but it serves me well, so I still use it for same basic tasks. I've installed the IPv6 stack on my local machine so you see here's my physical address and here's my IPv6 address. FE80::216E:CFF:E5EC and it puts a percent 6 at the end to let you know that it's an IPv6 address. So you can run this on Windows XP, Windows 2003, Vista comes up with it by Default and in fact I think you have to actually turn on IPv4 in Windows 7 if it doesn't detect a router or some other DHCP host or whatever on the network. So that concludes our discussion of IPv6 addressing. Stay tuned to this channel and we'll move into a lab and see how all this works together.
Tutorial Information
| Course: | Implementing Cisco IP Routing (642-902 ROUTE) |
| Author: | Greg Dickinson |
| SKU: | 34291 |
| ISBN: | 978-1-61866-028-2 |
| Release Date: | 2011-12-28 |
| Duration: | 10 hrs / 105 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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