iLab 2 Internet Protocol version 6 Stefan Liebald liebald@net.in.tum.de Lehrstuhl für Netzarchitekturen und Netzdienste Fakultät für Informatik Technische Universität München April 25, 2017 Based on slides of Lukas Schwaighofer 1
Address exhaustion Figure: IPv6 exhaustion (source: https://xkcd.com/865) 2
IPv4 and IPv6 Header 3
IPv6 Differences ◮ 128 bit addresses compared to 32 bit in IPv4 ◮ Fragmentation only on endhosts ◮ Header: ◮ Fixed header length (40 byte) + extension headers ◮ Fewer fields (no checksum, fragmentation) ◮ Integrated IPsec via extension header ◮ No more broadcast → multicast ◮ NDP instead of ARP 4
IPv6 Address notation ◮ 8 blocks of 2 bytes, colon seperated: ◮ e.g.: 2001:0db8:0000:0000:0000:0102:0000:0304 ◮ can be shortened: ◮ replace longest block of zeros with :: ◮ ommit leading zeros ◮ e.g. 2001:db8::102:0:304 ◮ What about ports? ◮ use [IPv6-address]:port ◮ e.g.: [2001:db8::102:0:304]:80 5
IPv6: Important well defined address types Address (subnet) Type ::1/128 Loopback fe80::/10 Link-local unicast fc00::/7 Unique Local unicast ff00::/8 Multicast 6
IPv6: Important multicast addresses Address Definition ff02::1 All nodes on local network segment ff02::2 All routers on local network segment ff02::1:2 All DHCPv6 servers on local network segment ff02::1:ff00:0/104 Solicited-node multicast prefix 7
Neighbor Discovery Protocol (NDP) ◮ Resolves MAC address of given IPv6 address to send packet over ethernet: ◮ Sender sends Neighbour Solicitation to target: ◮ IP dest: Solicitated Node Multicast IPv6 Address of target (prefix + last 3 octets of address) ◮ MAC dest: IPv6 multicast over ethernet address (33:33:+last 4 octets of v6 multicast address) ◮ Full IPv6 address of target as payload ◮ Target returns Neighbour Advertisment with MAC as payload 8
Outlook Stateless Address Auto Configuration 1. Generate Link Local (LL) address 2. Perform Duplicate Address Detection (DAD) ◮ Send Neighbour Solicitation to own LL address ◮ no response → assign address 3. Send Router Solicitation (RS) to all routers 4. Take information (prefix) from response (Router Advertisment (RA)) and configure global IP address 9
ICMPv6 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Type Code Checksum Message body 10
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