A brief overview on how networking works on IPv6. I'll try to explain how an ipv6 address is constructed, sub netting, and additional features it has over ipv4. Will try to keep it simple, and only address the core parts.

1. IPv6 - Overview
Raghu Udiyar
Systems Engineer at Linkedin
http://in.linkedin.com/in/raghusiddarth

2. Today is World IPv6 Day
6/6/14

3. 192.0.2.1 / 24
● 4 octets / 32 bits / ~ 4 billion addresses
● Limited addresss space
● NAT / PAT is a stop gap

4. 2001:0db8:0000:b02e:0f02:0000:0000:1001 / 64
● 8 hextets / 128 bits / 340 trillion trillion trillion
● Large addresss space
● No need for NAT

5. 2001:0db8:0000:b02e:0f02:0000:0000:1001 / 64
More than just a large address space :
– Improvements to other protocols like icmpv6
– Simplified header and options - fixed header at 40
bytes
– CIDR - classless interdomain routing
– Stateless autoconfiguration (SLAAC)
– No broadcast, only multicast
– Default gateway list, with auto failover

6. 2001:0db8:0000:b02e:0f02:0000:0000:1001/64
2001:db8:0:b02e:0f02::1001/64
● Remove Leading zeros
● Replace continuous zeros with double colon
● IPv6 url :
http://[2001:db8:85a3:8d3:1319:8a2e:370:7348]:443/

7. Structure

8. Structure

9. 2001:db8:0:b02e:0f02::1001/64
● 2001:db8:0 – Global Prefix /48
● 2001:db8:0:b02e – Subnet ID /64
● 0f02::1001 – Interface ID

10. 2001:db8:0:b02e:0f02::1001/64
● Typically ISP will assing /48 or /56
● /48 will mean 1 hextet or 16 bits for subnet
● /56 would mean 8 bits for subnet
● For /48 valid subnets would be :
– 2001:db8:0:0001::/64
– 2001:db8:0:0002::/64
– 2001:db8:0:b023::/64

11. Address Types
● Unicast, Anycast and Multicast ( no broadcast )
● all zero, and all ffff are allowed addresses
● Interface can have multiple ipv6 addresses

12. Unicast Address Types
● Global Unicast - 2000::/3
● Globaly routable
● Public IP's

13. Unicast Address Types
● Link-Local – fe80::/10
● Only valid on local segment or link
● Mandatory
● Automatically configured
– EUI-64 : OUI – ffee – Device ID
– Or random
● Ping6 fe80::232::1%eth0

14. Unicast Address Types
● Loopback – ::1/128
● Uspecified address – ::/128
● Unique Local – fc00::/7
– Only to be used within a site
– Private addresses

15. IP configuration
● Stateless
– SLAAC
– DHCPv6
● Stateful
– DHCPv6

16. Stateless Autoconfiguration
(SLAAC)
● Global Unicast address
● Get network and prefix from the router
● Interface ID
– EUI-64
– Random

17. Stateless Autoconfiguration
(SLAAC)
● Router periodically sends Router Advertisment (RA)
● with prefix, prefix length, default gateway, and link MTU
● Sent to all nodes multicast group
● Nodes can send Router Solicitation (RS)
● Sent to all routers multicast group
● Interface ID is auto configured using EUI-64 or random

18. DHCPv6
● Stateless
– RA, using 'O' flag indicates to get additional
information (dns, ntp, etc) from dhcp
● Stateful
– RA, using 'M' flag indcates to host to use dhcpv6 for
all addressing information
Note : for SLAAC M and O are set to 0

19. Multicast
● Multicast Listener Discovery (MDL)
● Nodes join and leave multicast groups using ICMPv6
MDL messages
● Efficient – nodes ignore packets for groups they have
not joined
● FF00::/8
– FF02::1 – All nodes group (link-local scope)
– FF02::2 – All routers group (link-local scope)
– FF05::2 – All routers group (site-local scope)

20. Neighbor Discovery Protocol
● NDP is over ICMPv6
● SLAAC
● Layer 2 address resolution
● Duplicate Address Detection (DAD)
● Router redirect

21. Layer 2 Address Resolution
● Node1 sends Neighbor Solicitation (NS)
– sent to the solicited node multicast address
– this is a special multicast address generated automatically based
on the ip address
● Node2 replies with Neighbor Advertisement (NA), with its
MAC address
● Node1 updates its Neighbor Cache

22. solicited node multicast address
● Every IP has one
– FF02:0:0:0:0:1:FF00::/104 + 24 bits of the unicast
address
● 33-33 + 32bits of IP address to form the MAC

23. Duplicate Address Detection
● Send NS with its own IP address

24. Router Redirect
● If a better route is present router with inform
host to take that router

25. IPv6 Transition
● Dual stack
– IPv6 and IPv4 co-exist
● Tunneling
– Encapsulate IPv6 packets in IPv4
● Translations
– Tranlate IPv4 header to IPv6

26. IPv6 in Linkedin
Demonstration