Without the tremendous functions Linux provides, I couldn’t go deeper in the road of seeking network technologies.  Learning Linux really help me broaden my vision. The feeling of freely use linux skills is really indescribable ^_^. After 2 days’ hard work,  I successfully emulated the ipv6 testbed on my lovable Gentoo server.  So far, all basic functions have been carried out  except mobile ipv6.  The testbed of Mobile IPV6 comprises a mobile device with ipv6 support, it’s no problem to me as I bought my favorite Nokia N900, this baby will play an important role in the show. However, N900′s default kernel doesn’t support ipv6 stack. Some little tweaking job has to be done.

Test 1:             IPV6 Tunnel

1.  Configured Tunnel

To setup a configured tunnel between R7 and R9 , tunnelling over IPV4 network.

root@Dom1 #ifconfig eth0

eth0      Link encap:Ethernet  HWaddr 00:16:3E:34:3C:C8

inet6 addr: 2001:0:0:1::10/64 Scope:Global

inet6 addr: 2001::1:216:3eff:fe34:3cc8/64 Scope:Global

inet6 addr: 2001::216:3eff:fe34:3cc8/64 Scope:Global

inet6 addr: fe80::216:3eff:fe34:3cc8/64 Scope:Link

UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

RX packets:123 errors:0 dropped:0 overruns:0 frame:0

TX packets:103 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:17238 (16.8 KiB)  TX bytes:11386 (11.1 KiB)

If there’re multiple global ipv6 address on one Ethernet port, which one will be used as source address, while sending packet of the box?

R9#s run int tun0

Building configuration…

interface Tunnel0

no ip address

ipv6 address 2003::9/64        configure ipv6 here is not mandatory option,

tunnel source Loopback0       the purpose of configuring ipv6 address is to

tunnel destination 7.7.7.7     enable ipv6 function. “ipv6 enable”

tunnel mode ipv6ip

R7#s run int tun 0

interface Tunnel0

no ip address

ipv6 address 2003::7/64

tunnel source Loopback0

tunnel destination 9.9.9.9

tunnel mode ipv6ip

end

2.   6to4 Tunnel

Reassigning IPV6 address to both network to comply with 6to4 addressing rule.

R7#s run int tun 0

interface Tunnel0

no ip address

no ip redirects

ipv6 unnumbered FastEthernet0/1

tunnel source Loopback0

tunnel mode ipv6ip 6to4

end

R9#s run int tun 0

interface Tunnel0

no ip address

no ip redirects

ipv6 unnumbered Loopback0

tunnel source Loopback0

tunnel mode ipv6ip 6to4

root@Dom1 #ifconfig eth0 inet6 add 2002:77:77:1::10/64

root@Dom1 #ip -f inet6 route add ::/0 via 2002:77:77:1::1

root@Dom1 #ip -f inet6 route show

2002:77:77:1::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295

fe80::/64 dev eth0  metric 256  expires -193sec mtu 1500 advmss 1440 hoplimit 4294967295

ff00::/8 dev eth0  metric 256  expires -193sec mtu 1500 advmss 1440 hoplimit 4294967295

default via fe80::c800:13ff:feee:6 dev eth0  proto kernel  metric 1024  expires 1759sec mtu 1500 advmss 1440 hoplimit 64

default via 2002:77:77:1::1 dev eth0  metric 1024  expires -34sec mtu 1500 advmss 1440 hoplimit 4294967295

R7#deb tunnel

Tunnel Interface debugging is on

R7#

*Apr 22 14:00:27.075: Tunnel0: IPv6/IP 6to4 adjacency fixup, 7.7.7.7->9.9.9.9, tos set to 0×0

*Apr 22 14:00:27.199: Tunnel0: IPv6/IP to classify 9.9.9.9->7.7.7.7 (tbl=0,”IPv4:Default” len=124 ttl=251 tos=0×0) ok, oce_rc=0×0

ICMP ECHO REQUEST PACKET FROM R7 TO R9:

Internet Protocol, Src: 7.7.7.7 (7.7.7.7), Dst: 9.9.9.9 (9.9.9.9)

Version: 4

Header length: 20 bytes

Differentiated Services Field: 0×00 (DSCP 0×00: Default; ECN: 0×00)

0000 00.. = Differentiated Services Codepoint: Default (0×00)

…. ..0. = ECN-Capable Transport (ECT): 0

…. …0 = ECN-CE: 0

Total Length: 124

Identification: 0×0149 (329)

Flags: 0×00

0.. = Reserved bit: Not Set

.0. = Don’t fragment: Not Set

..0 = More fragments: Not Set

Fragment offset: 0

Time to live: 252

Protocol: IPv6 (0×29)

Header checksum: 0x9cf0 [correct]

[Good: True]

[Bad : False]

Source: 7.7.7.7 (7.7.7.7)

Destination: 9.9.9.9 (9.9.9.9)

Internet Protocol Version 6

0110 …. = Version: 6

[0110 .... = This field makes the filter "ip.version == 6" possible: 6]

…. 0000 0000 …. …. …. …. …. = Traffic class: 0×00000000

…. …. …. 0000 0000 0000 0000 0000 = Flowlabel: 0×00000000

Payload length: 64

Next header: ICMPv6 (0x3a)

Hop limit: 63

Source: 2002:707:707:1:216:3eff:fe5e:3c1c (2002:707:707:1:216:3eff:fe5e:3c1c)

Destination: 2002:909:909:1::40 (2002:909:909:1::40)

Internet Control Message Protocol v6

Type: 128 (Echo request)

Code: 0

Checksum: 0xd41f [correct]

ID: 0x1a0b

Sequence: 0×0000

Data (56 bytes)

3.  IPV6 over GRE tunnel

IPV6 Replacement of ARP:

Ethernet II, Src: Xensourc_01:44:da (00:16:3e:01:44:da), Dst: IPv6mcast_ff:00:00:01 (33:33:ff:00:00:01)

Destination: IPv6mcast_ff:00:00:01 (33:33:ff:00:00:01)

Source: Xensourc_01:44:da (00:16:3e:01:44:da)

Type: IPv6 (0x86dd)

Internet Protocol Version 6

0110 …. = Version: 6

…. 0000 0000 …. …. …. …. …. = Traffic class: 0×00000000

…. …. …. 0000 0000 0000 0000 0000 = Flowlabel: 0×00000000

Payload length: 32

Next header: ICMPv6 (0x3a)

Hop limit: 255

Source: 2002:909:909:1::40 (2002:909:909:1::40)

Destination: ff02::1:ff00:1 (ff02::1:ff00:1)

Internet Control Message Protocol v6

Type: 135 (Neighbor solicitation)

Code: 0

Checksum: 0×9241 [correct]

Target: 2002:909:909:1::1 (2002:909:909:1::1)

ICMPv6 Option (Source link-layer address)

Type: Source link-layer address (1)

Length: 8

Link-layer address: 00:16:3e:01:44:da

==================================================================================

Ethernet II, Src: ca:02:13:ee:00:06 (ca:02:13:ee:00:06), Dst: Xensourc_01:44:da (00:16:3e:01:44:da)

Destination: Xensourc_01:44:da (00:16:3e:01:44:da)

Source: ca:02:13:ee:00:06 (ca:02:13:ee:00:06)

Type: IPv6 (0x86dd)

Internet Protocol Version 6

0110 …. = Version: 6

…. 1110 0000 …. …. …. …. …. = Traffic class: 0x000000e0

…. …. …. 0000 0000 0000 0000 0000 = Flowlabel: 0×00000000

Payload length: 32

Next header: ICMPv6 (0x3a)

Hop limit: 255

Source: 2002:909:909:1::1 (2002:909:909:1::1)

Destination: 2002:909:909:1::40 (2002:909:909:1::40)

Internet Control Message Protocol v6

Type: 136 (Neighbor advertisement)

Code: 0

Checksum: 0x212b [correct]

Flags: 0xe0000000

1… …. …. …. …. …. …. …. = Router

.1.. …. …. …. …. …. …. …. = Solicited

..1. …. …. …. …. …. …. …. = Override

Target: 2002:909:909:1::1 (2002:909:909:1::1)

ICMPv6 Option (Target link-layer address)

Type: Target link-layer address (2)

Length: 8

Link-layer address: ca:02:13:ee:00:06

IPV6 Fragmentation:

root@dom4 #ping6 2002:909:909:1::1 -s 1500 -c 1

F1:14(ether frame)+40(IPV6 header)+8(IPV6 fragment header)+ 8(ICMP) + 1440(DATA) = 1510

F2: 14(ether frame)+40(IPV6 header)+8(IPV6 fragment header)+ 60(DATA) = 122

From the above two formulas, we can deduce that S option is used to specify the payload of

ICMP.

root@dom4 #ifconfig eth0

eth0      Link encap:Ethernet  HWaddr 00:16:3E:01:44:DA

inet addr:192.168.1.79  Bcast:192.168.1.255  Mask:255.255.255.0

inet6 addr: 2002:909:909:1::40/64 Scope:Global

inet6 addr: 2002:909:909:1:216:3eff:fe01:44da/64 Scope:Global

inet6 addr: 2002:99:99:1:216:3eff:fe01:44da/64 Scope:Global

inet6 addr: fe80::216:3eff:fe01:44da/64 Scope:Link

UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

RX packets:845 errors:0 dropped:0 overruns:0 frame:0

TX packets:440 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:181032 (176.7 KiB)  TX bytes:51132 (49.9 KiB)

root@dom4 #ping6 2002:909:909:1::1 -s 1452 -c 1

14(ether frame)+40(IPV6 header)+8(ICMP)+ 1452(DATA) = 1514

This ICMPv6 is not being fragmented.

Send ICMPv6 from R9 to dom4 via f0/1.

R9#sh int f0/1

FastEthernet0/1 is up, line protocol is up

Hardware is i82543 (Livengood), address is ca02.13ee.0006 (bia ca02.13ee.0006)

MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,

reliability 255/255, txload 1/255, rxload 1/255

R9#sh ipv int f0/1

FastEthernet0/1 is up, line protocol is up

IPv6 is enabled, link-local address is FE80::C802:13FF:FEEE:6

No Virtual link-local address(es):

Global unicast address(es):

2002:909:909:1::1, subnet is 2002:909:909:1::/64

Joined group address(es):

FF02::1

FF02::2

FF02::1:FF00:1

FF02::1:FFEE:6

MTU is 1500 bytes

Ethernet MTU :1500

IPV6 MTU:1500

R9#ping ipv6 2002:909:909:1::40 repeat 1 size 1452 (size option specify the whole ipv6 packet including ipv6 header)

So the total byte is 1466 on wire.

R9#ping ipv6 2002:909:909:1::40 repeat 1 size 1500

1514 bytes on wire,  no fragmentation.

Ethernet MTU :1500

IPV6 MTU: 1499

interface FastEthernet0/1

mtu 1530

ipv6 address 2002:909:909:1::1/64

R9#sh ipv int f0/1

FastEthernet0/1 is up, line protocol is up

IPv6 is enabled, link-local address is FE80::C802:13FF:FEEE:6

No Virtual link-local address(es):

Global unicast address(es):

2002:909:909:1::1, subnet is 2002:909:909:1::/64

Joined group address(es):

FF02::1

FF02::2

FF02::1:FF00:1

FF02::1:FFEE:6

MTU is 1530 bytes

R9#sh int f0/1

FastEthernet0/1 is up, line protocol is up

Hardware is i82543 (Livengood), address is ca02.13ee.0006 (bia ca02.13ee.0006)

MTU 1530 bytes, BW 100000 Kbit/sec, DLY 100 usec,

4.  ISATAP  Tunnel ( Pending)

5.  Mobile IPV6 (Pending)