1. Cisco Hands-On Training
IPv6 theory
Darrell Root Sep-09 www.ciscohandsontraining.com
This presentation will be posted in the episode
comments on the website
Saturday, September 19, 2009

2. IPv4 address exhaustion
(www.potaroo.net)
Saturday, September 19, 2009

3. OSI layer review
source: http://www.softpanorama.org/Net/Images/tcp_ip_layers.gif
Saturday, September 19, 2009

4. Ethernet frame format
Ethernet frame type 0x0800=IPv4
Ethernet frame type 0x86DD=IPv6
source: http://cs.uccs.edu/~cs522/msgformat/hw1_ht1.gif
Saturday, September 19, 2009

5. TCP segment format (RFC 793)
Saturday, September 19, 2009

6. HTTP tcpdump is very
familiar
Saturday, September 19, 2009

7. UDP format (RFC 768)
Saturday, September 19, 2009

8. IPv4 and IPv6 header format
(source: h3c.com)
Saturday, September 19, 2009

9. IPv6 extension headers
(from www.cisco.com)
Saturday, September 19, 2009

10. IPv6 extension headers
(from wikipedia)
Saturday, September 19, 2009

11. IPv6 address example
and shortening rules
192.168.33.76
2001:0db8:0032:0000:0000:5bf0:3f2d:8f8a
2001:db8:32::5bf0:3f2d:8f8a
Saturday, September 19, 2009

12. IPv6 netmasks
2001:0db8:0032:48c3:4f21:5bfe:3f2d:8f8a
2001:0db8::/32 Typical small ISP allocation
Typical allocation for
2001:0db8:0032::/48 enterprise, building, or home
2001:0db8:0032:48c3::/ Typical subnet (including p2p
64 links)
2001:0db8:0032:48c3:4 Loopback interface
f21:5bfe:3f2d:8f8a/128
Saturday, September 19, 2009

13. IPv6 netmask sizes
65536 sites each with
/32
/48
65536 subnets each of
/48
size /64
One subnet with 16
/64
billion billion hosts
Used for loopback
/128
interfaces
Saturday, September 19, 2009

14. subnet mask drill
2345:6789:abcd:ef01:2345:6789:abcd:ef01
2345:6789:abcd:ef00::/63
0x1=1 0001
/16 /32 /48 /64 /128
/8 /44 /52 /60
/43 /45 /50 /62 /63
Saturday, September 19, 2009

15. 2345:6789:abcd:ef01:2345:6789:abcd:ef01/128
2345::/16 2345:6789:abcd::/48
2345:6789::/32 2345:6789:abcd:ef01::/64
2300::/8 2345:6789:abc0::/44
2345:6789:abcd:e000::/52
2345:6789:abcd:ef00::/60
2345:6789:abc0::/43
2345:6789:abc8::/45
2345:6789:abcd:c000::/50
2345:6789:abcd:ef00::/62
2345:6789:abcd:ef00::/63
Saturday, September 19, 2009

16. IPv6 address types
(www.iana.org)
2000::/3 through 3fff::/3 Global Unicast
fc00::/7 through fdff::/7 Unique local unicast
fe80::/10 through febf::/10 Link local unicast
ff00::/8 through ffff::/8 multicast
Saturday, September 19, 2009

17. IPv6 multicast addresses
(source: edge.networkworld.com)
Saturday, September 19, 2009

18. ipv6 well known
multicast addresses
• ff02::1 all hosts on local subnet
• ff02::2 all routers on local subnet
• ff02::5, ff02::6 OSPFv3
• ff02::9 RIPng
Saturday, September 19, 2009

19. IPv6 multicast to
ethernet multicast
(src: technet.microsoft.com)
Saturday, September 19, 2009

20. IPv6 neighbor solicitation
sudo tcpdump -e -n icmp6
00:22:41:27:a4:0a > 33:33:ff:00:00:01, ethertype IPv6
(0x86dd), length 86: 2001:db8:1f05:2e5:222:41ff:fe27:a40a >
ff02::1:ff00:1: ICMP6, neighbor solicitation, who has
2001:db8:1f05:2e5::1, length 32
00:1f:f3:3c:fc:d5 > 00:22:41:27:a4:0a, ethertype IPv6
(0x86dd), length 86: 2001:db8:1f05:2e5::1 >
2001:db8:1f05:2e5:222:41ff:fe27:a40a: ICMP6, neighbor
advertisement, tgt is 2001:db8:1f05:2e5::1, length 32
Saturday, September 19, 2009

21. IPv6 duplicate address
detection
00:1b:63:f0:8a:93 > 33:33:ff:f0:8a:93, ethertype IPv6
(0x86dd), length 78: :: > ff02::1:fff0:8a93: ICMP6, neighbor
solicitation, who has fe80::21b:63ff:fef0:8a93, length 24
(no reply, so no duplicate address detected)
Saturday, September 19, 2009

22. IPv6 router
advertisements
00:1f:f3:3c:fc:d5 > 33:33:00:00:00:01, ethertype IPv6 (0x86dd),
length 110: (hlim 255, next-header ICMPv6 (58) payload length:
56) fe80::21f:f3ff:fe3c:fcd5 > ff02::1: [icmp6 sum ok] ICMP6, router
advertisement, length 56
hop limit 64, Flags [none], pref medium, router lifetime 1800s,
reachable time 0s, retrans time 0s
source link-address option (1), length 8 (1): 00:1f:f3:3c:fc:d5
0x0000: 001f f33c fcd5
prefix info option (3), length 32 (4): 2001:db8:1f05:2e5::/64, Flags
[onlink, auto], valid time 2592000s, pref. time 604800s
Saturday, September 19, 2009

23. IPv6 address stateless
autoconfiguration (RFC2462)
• Host has MAC address 1234:5678:90ab
• After using duplicate address detection, host
assumes IPv6 link-local address
fe80::1234:56FF:FE78:90ab
• Host sends router solicitation and receives
router advertisement with prefix
2001:db8:1234:5678::/64
• Host uses DAD and eventually assumes IPv6
address
2001:db8:1234:5678:1234:56FF:FE78:90ab
Saturday, September 19, 2009

24. IPv6 Cisco IOS support
• Introduced in 12.2T
• Integrated into mainline in 12.3
• Many recent new features, so use at least 12.4
mainline
• For cat6, use 12.2(18)SXF or later (currently 12.2
(18)SXF16, 12.2(33)SXH5, or 12.2(33)SXI2a
• IP plus feature set, or advanced IP services
feature set (very recent releases include it in IP
services)
Saturday, September 19, 2009

25. IPv6 map example
All IPv6 addresses start with:
2001:0db8:0: Top
lo0 1::1/128
s0 s1
2::1/64 1::5/126
s1 s0
2::2/64 1::6/126
s0 s1
3::1/64 3::2/64
Middle bottom
lo0 1::2/128 lo0 1::3/128
Saturday, September 19, 2009

26. IPv6 configuration
example
ipv6 unicast-routing
interface Serial1
no ip address
ipv6 address 2001:DB8:0:2::2/64
ipv6 rip bob enable
clock rate 64000
!
ipv6 router rip bob
Saturday, September 19, 2009