12 IPv6

And Still More

1. IPv6 uses the "/x" Classless Inter-Domain Routing (CIDR) nomenclature Example address and subnet for a typical IPv6 host: fe80::cf:0:ba98:1234/64 2. •IPv6 loopback address -::1 -Represents 0000:0000:0000:0000:0000:0000:0000:0001

6in4 Tunnels

1. Teredo: second NAT-traversal IPv6 tunneling protocol Built into Microsoft Windows •Addresses start with 2001:0::/32 Most people prefer to skip Windows built-in support Get third-party tool that supports 6to4 or 6in4 2. Miredo Tunnels Open-source implementation of Teredo for Linux and other UNIX-based systems

Global Unicast Address

A global unicast address is required for Internet access. Devices get GUA from their default gateway. When they boot up a computer sends out a router solicitation message (ff02::2) looking for a router The router tells the computer the prefix. The computer takes the prefix and adds the interface identifier or EUI-64 address Global address results from the combination

Moving to IPv6

IPv4 and IPv6 -Can run both IPv4 and IPv6 on your computers and routers at the same time •Parts of the Internet ready for IPv6 -All root DNS servers support IPv6 resolution -Almost all tier-one ISP routers properly forward IPv6 packets •Routers and servers may not yet be IPv6-ready/turned on. But all root DNS servers support IPv6 and almost all Tier 1 ISP routers proerply forward IPv6 packets.

Popularity

IPv4 is still more used but IPv6 is seen as inevitable. Since you pay for IP addresses startups often prefer IPv6 because they are afraid IPv4 limited longevity make them poor value for the money.

Transition Mechanisms

IPv4-to-IPv6 tunnels bridge the gap to full transition. 4to6 You can encapsulate IPv6 traffic into an IPv4 (is this right or should it be flipped?) tunnel to get to an IPv6-capable router. You can download software to do this for you. 6in4 •Also called IPv6-in-IPv4 •One of the most popular tunneling standards •One of only two tunneling protocols that can go through a NAT

The End of Broadcast

IPv6 link-local address is a unicast address. It is a unique address exclusive to that system. The multicast address is a set of reserved addresses designed to go to certain systems. In IPv4, any Class D addresses that start with 224.0.0.0/4 are reserved for multicast.. For example, if a system is configured to use the Network Time Protocol it will listen to 224.0.1.1 for multicast time information. •Only specific applications used multicast. In IPv6, several IPv6-only multicast addresses are added to get specific jobs done

Using IPv6

IPv6 works with almost no interference or interaction from anyone. It rarely needs static IP addresses. DHCP is almost nonexistent in IPv6. Neighbor Discovery Protocol (NDP) makes the IPv6 automation work

Link-Local Address

If a network is not connected to a server, then each host on the network will have a permanent IPv6 address. This is rare. More common is that when a device boots up it gives itself a link local address much like APIPA. This address always begins fe80:0000:0000:0000 or fe8/10 followed by 54 zero bits. There are two ways of generating the second half of the address.

DNS in IPv6

Most DNS servers now support IPv6 addresses DNS servers supporting IPv6 use AAAA records. (these are four times the length of IPv4 addresses.

Aggregation

Most routers have a default path. Tier-one routers that connect to other tier-one routers cannot have any default route. They are known as no-default routers and have huge routing table (750,000 routes)group; gathering. Aggreation is a way to make the top tiers work more efficiently. In aggregation: every router uses a subset of the next higher router's existing routes. This reduces size and complexity of routing tables. Gives detailed geographic picture of Internet organization This is part of IPv6 but was impossible to apply to IPv4 because too many commitments to addresses would have had to have been revoked. So, IPv6 addresses may change on computers because a change at the top has filtered down to them. This is not common but does happen.

Multicasting

Multicast packets are encapsulated into Ethernet frames Address 01-00-5e-xx-xx-xx are reserved for IPv4 multicast frame destination addresses Address 33-33-xx-xx-xx-xx is used on Ethernet frames encapsulating IPv6 multicast packets Every computer sees the multicast frame It is only processed by computers set up to process the frame

How aggregation works

The default gateway gives the first 64 bits of the IP address to computers The router gets its 48-bit prefix from the upstream router The router adds its own 16-bit subnet

More on Addresses

The first 64 bits are called the network prefix and is used for routing. It is broken into a global routing prefix (48 bits) and a subnet ID(16 bits) The second 64 bits is called the interface ID.

IPv6 Prefix lengths

The max length is 64 bits. Last 64 bits of an IPv6 address are generated by the NIC, leaving a maximum of 64 bits for the subnet—no subnet is ever longer than /64 The five RIRs Regional Internet Registries give 48 bit prefixes to large ISPs and users who need large allotments. Most users get 64 bit interface ids Local link addressing uses a prefix length of /64. Other types of addresses get info from their router.

GENERATING THE SECOND hALF

The new way is for every device to generate a 64 bit random number The old way is to use the device's MAC address to generate a unique 64 bit number called an extended unique identifier, 64 bit (EUI-64)

Neighbor Discovery Protocol (NDP)

There are five packet types in NDP. 1. Neighbor solicitation when a computer joins a network it sends out a multicast NS searching for other computers in its domain. The packets begin with ff02 so only IPv6 capable machines hear/read them 2. Neighbor advertisement - any IPv6 machine will respond with and acknowledgement of receipt and info about its addressing. This is like IPv4 ARP. 3. Router solicitation - really all this happens in step 4. 4. Router advertisement create unique IDs for IPv6 networks. To do this IPv6 relies on router advertisements instead of NAT and private network IDs. The router receives a global prefix (usually 48 bits) and a unique subnet ID for the LAN (usually 16 bits). The outer sends that information to all the LAN hosts via a router advertisement 5. Redirect - this on is less important.

DHCPv6

There are some situations where you want to use DHCP-like protocols because you have a special device configuration. DHCPv6 works differently than in IPv4 The IP address and subnet are received from the gateway router DHCPv6 provides other information •Two modes of DHCPv6 -Stateful - works like DHCP in IPv4 -Stateless - only passes out optional information -Stateless is the norm

Anycast

This is used commonly in DNS. Every DNS server keeps IP addresses of root servers in a root hints file. Anycasting gives clusters of computers the same IP address. Then, routers use the Border Gateway Protocol (BGP) to determine the closest computer and sends the packet to its anycast address. Only the server using BGP knows it has limited the scope of the transmission.

Prefix Delegation

When this is enableed the router knows to go upstream to the ISP and get a prefix to hand out to clients.

Why IPv6

With 32 bits to use in determingin the IP address of a computer you can accomadate 4 billion computers. Turns out there are or soon will be more. The allocation methiod wastes addresses So IPv6 was developed with uses 128 bit addresses allowing for 3.4 *10^38 uniques addresses. It also gives better security and routing. The improved security is called IPS IP Sec protocol.

Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)

Works within an IPv4 network Adds IPv4 address to an IPv6 prefix for endpoints Example address: 2001:db8::98ca:200:131.107.28.9. Other tunneling standards have more common IPv6 addressing structure

How to check IPv6 is working

You can check the IP status to see if IPv6 is running with these commands. ipconfig in Windows ip addr in Linux or macOS

Overlay Tunnels

•Enables two IPv6 networks to connect over an existing IPv4 infrastructure, e.g., the Internet •The routers that connect the IPv6 networks to the IPv4 infrastructure: -Run dual stack—both IPv4 and IPv6 -Can encapsulate the traffic from the local network into IPv4 packets •Can connect an IPv4 client to an IPv6 network: -Using protocols—like 4to6, ISATAP, and others—or -By creating manual tunnels

IPv6 Basics

•IPv6 and IPv4 differ in implementation 1. Addressing numbers work differently. IPv6 uses 128 bits. They are written as 8 groups of 4 hex characters separated by colons. The groups are called quartetx or hextets. Leading zeros can be dropped. If there are consecutive hextets of four zeros they can be represented by double colons but this can only be done once. 2. Addressing numbers do not look alike 3. IPv6 always uses link-local addressing 4. Subnetting works differently

NAT64

•IPv6 has no need or use for classic network address translation (NAT) •NAT64 is a transition mechanism that embeds IPv4 packets into IPv6 packets for network traversal •NAT64 gateway handles traffic between the IPv4 and IPv6 segments -Does translation on-the-fly -Keeps track of who's who on either end

Tunnel Brokers

•Someone must act as the far endpoint(what does this mean?) Must know the tunneling standard and how to connect to the endpoint Create the actual tunnel. Usually offer a custom-made endpoint client. May use automatic configuration protocols. -Tunnel Setup Protocol (TSP) -Tunnel Information and Control protocol (TIC)