Link-Local Address にまつわる エトセトラ 2012/11/03 IPv6SG #03 The document discusses link-local addresses in IPv6 and summarizes findings from testing on various platforms. It covers default prefix lengths, setting a link-local on loopback interfaces, valid prefix lengths when configuring different link-local addresses, and notices differences in implementations between Cisco, Linux, Solaris, BSD and other operating systems.

1. Link-Local Address
にまつわる
エトセトラ
2012/11/03 IPv6SG #03
@twovs
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2. agenda
• 自己紹介
• クイズ
• 聞きたいこと
• 調べてみたこと
• まとめ
• 気付いたこと 2
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3. 自己紹介
• @twovs
• 無線LAN装置の開発(1999∼2004)
• オンラインゲームのシステム管理者
(2004∼)
• ただし、ゲームには全く興味無し...
• ZFS 最高 ! beadm 便利 !
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4. クイズ
Link-Local Address は
fe80::0/10 ですか ? (YES/NO)
つまり、最初の 10bit が
'1111 1110 10' だと Link-Local ?
1111 1110 1000 0000 : 0000 0000 0000 0000 : ...
f e 8 0 : 0 0 0 0 : ...
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5. fe80:1::1 や febf::1 も
Link-Local Address ?
1111 1110 1000 0000 : 0000 0000 0000 0001 : ...
f e 8 0 : 0 0 0 1 : ...
1111 1110 1011 1111 : 0000 0000 0000 0000 : ...
f e b f : 0 0 0 0 : ...
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6. 答え = NO (だと思う)
RFC4291 Section 2.5.6.
Link-Local IPv6 Unicast Addresses
Link-Local addresses are for use on a
single link. Link-Local addresses have the
following format:
| 10 |
| bits | 54 bits | 64 bits |
+----------+-------------------------+----------------------------+
|1111111010| 0 | interface ID |
+----------+-------------------------+----------------------------+
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7. fe80:1::1 や febf::1 は
11-64 bits が 0 でないから
Link-Local Address ではないと思う
1111 1110 1000 0000 : 0000 0000 0000 0001 : ...
f e 8 0 : 0 0 0 1 : ...
1111 1110 1011 1111 : 0000 0000 0000 0000 : ...
f e b f : 0 0 0 0 : ...
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8. でも Cisco は...
febf::1 (11-64bit = '0' でない) が
Link-Local Addr になる(なってしまう)
Cisco1812#show ipv6 interface FastEthernet 0
FastEthernet0 is up, line protocol is up
IPv6 is enabled, link-local address is FEBF::1
No Virtual link-local address(es):
No global unicast address is configured
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF00:1
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9. でも CentOS は...
febf::1 (11-64bit = '0' でない) が
scope=link になる(なってしまう)
[CentOS6.3]# ip -f inet6 addr show dev eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
inet6 fe80::a00:27ff:febb:1443/64 scope link
valid_lft forever preferred_lft forever
[CentOS6.3]# ip -f inet6 addr add febf::1 dev eth0 scope link
[CentOS6.3]# ip -f inet6 addr show dev eth0 scope link
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
inet6 febf::1/128 scope link
valid_lft forever preferred_lft forever
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10. でも Solarisは...
febf::1 (11-64bit = '0' でない) が
Link-Local Addr になる(なってしまう)
[Solaris11.1]$ ipadm show-addr
ADDROBJ TYPE STATE ADDR
lo0/v6 static ok ::1/128
net0/v6 static ok febf::1/10
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11. 聞きたいこと.1
サーバに設定する
DefaultGW どうします?
• 前回の IPv6SG #02 でも質問しました
• HSRP を使うなら Link-Local ?
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12. 聞きたいこと.2
Loopback Interface に
Link-Local Addr を
設定する?
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13. 聞きたいこと.3
I/F に設定する Link-Local
Addr の prefix 長は
/64 ? それとも /10 ?
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14. 調べてみた
1. デフォルトの prefix length
2. loopback I/F への Link-Local
3. fe80::1 を設定した時の prefix length
4. fe80::64/64 の設定可否
5. fe80::10/10 の設定可否
6. febf::1 を設定した時の prefix length
7. febf::64/64 の設定可否
8. febf::10/10 の設定可否
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15. 対象
a. Cisco (IOS 12.4)
b. Linux/CentOS6.3
c. Solaris 11.1
d. SEIL/CLI (4.00/OutsidersEdge)
e. SEIL/SHELL (NetBSD 3.1_STABLE)
f. NetBSD6.0
g. FreeBSD9.0
h. OpenBSD5.1
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16. まとめ
1 2 3 4 5 6 7 8
a. Cisco /10 x /10 x x /10 x x
b. CentOS6.3 /64 x /128 o o /128 o o
c. Solaris11.1 /10 x /10 o o /10 o o
d. SEIL/CLI /64 fe80::1/64 /64 o x x x x
e. SEIL/SHELL /64 fe80::1/64 /64 o o /64 o o
f. NetBSD6.0 /64 fe80::1/64 /64 o o /64 o o
g. FreeBSD9.0 /64 fe80::1/64 /64 o o /64 o o
h. OpenBSD5.1 /64 fe80::1/64 /64 o o /64 o o
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17. 気付いたこと.1
1 2 3 4 5 6 7 8
a. Cisco /10 x /10 x x /10 x x
b. CentOS6.3 /64 x /128 o o /128 x x
c. Solaris11 /10 x /10 o o /10 o o
d. SEIL/CLI /64 fe80::1/64 /64 o x x x x
e. SEIL/SHELL /64 fe80::1/64 /64 o o /64 o o
f. NetBSD6.0 /64 fe80::1/64 /64 o o /64 o o
g. FreeBSD9.0 /64 SEIL /64 o o /64
のこだわり(?)
fe80::1/64 o o
h. OpenBSD5.1 /64 fe80::1/64 /64 o o /64 o o
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18. http://www.seil.jp/
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19. 気付いたこと.2
BSD の実装
In the kernel, an interface index for link-
local scoped address is embedded into
2nd 16bit-word (3rd and 4th byte) in IPv6
address. For example, you may see
something like:
fe80:1::200:f8ff:fe01:6317
FreeBSD Developers' Handbook / Chapter 8 IPv6 Internals
http://www.freebsd.org/doc/en/books/developers-handbook/ipv6.html#ipv6-scope-index
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20. [FreeBSD9.0]# ifconfig em0 inet6
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
[FreeBSD9.0]# ifconfig em0 inet6 fe80:ffff:ffff:ffff:1111:2222:3333:4444/64 alias
[FreeBSD9.0]# ifconfig em0 inet6
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
inet6 fe80:0:ffff:ffff:1111:2222:3333:4444%em0 prefixlen 64 scopeid 0x1
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
[FreeBSD9.0]# /usr/sbin/route6d
自動的に 0 に修正
[FreeBSD9.0]# kill -SIGINT `cat /var/run/route6d.pid
[FreeBSD9.0]# cat /var/run/route6d_dump
15:50:47: Interface Table Dump
Number of interfaces: 2
1 (index = 1)
advertising interfaces:
(snip)
em0: index(1) flags(UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST)
addr( fe80:1:ffff:ffff:1111:2222:3333:4444) mtu(1500) metric(0)
fe80:1:ffff:ffff:1111:2222:3333:4444/64
(snip)
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21. [FreeBSD9.0]# man route6d
(snip)
Internally route6d embeds interface
identifier into bit 32 to 63 of link-local
addresses (fe80::xx and ff02::xx) so they
will be visible on internal state dump file
(/var/run/route6d_dump).
16 to 31 の間違い
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22. Thank You
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23. [参考] b. CentOS
[CentOS6.3]# ip -f inet6 addr show dev eth0 scope link
[CentOS6.3]# ip -f inet6 addr add fe80::1 dev eth0 scope link
[CentOS6.3]# ip -f inet6 addr add fe80::64/64 dev eth0 scope link
[CentOS6.3]# ip -f inet6 addr add fe80::10/10 dev eth0 scope link
[CentOS6.3]# ip -f inet6 addr add febf::1 dev eth0 scope link
[CentOS6.3]# ip -f inet6 addr add febf::64/64 dev eth0 scope link
[CentOS6.3]# ip -f inet6 addr add febf::10/10 dev eth0 scope link
[CentOS6.3]# ip -f inet6 addr show dev eth0 scope link
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
inet6 febf::10/10 scope link
valid_lft forever preferred_lft forever
inet6 febf::64/64 scope link
valid_lft forever preferred_lft forever
inet6 febf::1/128 scope link
valid_lft forever preferred_lft forever
inet6 fe80::10/10 scope link
valid_lft forever preferred_lft forever
inet6 fe80::64/64 scope link
valid_lft forever preferred_lft forever
inet6 fe80::1/128 scope link
valid_lft forever preferred_lft forever
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24. [参考] c. Solaris 11.1
[Solaris11.1]# ipadm show-addr
ADDROBJ TYPE STATE ADDR
lo0/v6 static ok ::1/128
net0/v6 addrconf ok fe80::a00:27ff:fe63:4cff/10
[Solaris11.1]# ipadm create-addr -T static -a local=fe80::1 net0/IPv6SG3
[Solaris11.1]# ipadm create-addr -T static -a local=fe80::64/64 net0/IPv6SG4
[Solaris11.1]# ipadm create-addr -T static -a local=fe80::10/10 net0/IPv6SG5
[Solaris11.1]# ipadm create-addr -T static -a local=febf::1 net0/IPv6SG6
[Solaris11.1]# ipadm create-addr -T static -a local=febf::64/64 net0/IPv6SG7
[Solaris11.1]# ipadm create-addr -T static -a local=febf::10/10 net0/IPv6SG8
[Solaris11.1]# ipadm show-addr
ADDROBJ TYPE STATE ADDR
lo0/v6 static ok ::1/128
net0/v6 addrconf ok fe80::a00:27ff:fe63:4cff/10
net0/IPv6SG3 static ok fe80::1/10
net0/IPv6SG4 static ok fe80::64/64
net0/IPv6SG5 static ok fe80::10/10
net0/IPv6SG6 static ok febf::1/10
net0/IPv6SG7 static ok febf::64/64
net0/IPv6SG8 static ok febf::10/10
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25. [参考] d-1. SEIL(CLI)
SEIL-X1# show status interface lan0
interface lan0:
(snip)
EthernetAddress=00:E0:4D:xx:xx:xx
IP address=192.168.0.1 netmask=255.255.255.0 broadcast=192.168.0.255
IPv6 address=fe80::2e0:4dff:fexx:xxxx%lan0 prefixlen=64 scopeid 0x1
SEIL-X1# interface lan0 add fe80::1
SEIL-X1# interface lan0 add fe80::64/64
SEIL-X1# interface lan0 add fe80::10/10
^
error: invalid prefix length
SEIL-X1# interface lan0 add febf::1
^
error: invalid address
SEIL-X1# interface lan0 add febf::64/64
^
error: invalid address
SEIL-X1# interface lan0 add febf::10/10
^
error: invalid prefix length
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26. [参考] d-2. SEIL(CLI)
SEIL-X1# show status interface lan0
interface lan0:
(snip)
EthernetAddress=00:E0:4D:xx:xx:xx
IP address=192.168.0.1 netmask=255.255.255.0 broadcast=192.168.0.255
IPv6 address=fe80::2e0:4dff:fexx:xxxx%lan0 prefixlen=64 scopeid 0x1
IPv6 address=fe80::1%lan0 prefixlen=64 scopeid 0x1
IPv6 address=fe80::64%lan0 prefixlen=64 scopeid 0x1
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27. [参考] f. NetBSD6.0
[NetBSD6.0]# ifconfig wm0 inet6
wm0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
(snip)
inet6 fe80::a00:27ff:fe9a:7e50%wm0 prefixlen 64 scopeid 0x1
[NetBSD6.0]# ifconfig wm0 inet6 fe80::1 alias
[NetBSD6.0]# ifconfig wm0 inet6 fe80::64/64 alias
[NetBSD6.0]# ifconfig wm0 inet6 fe80::10/10 alias
[NetBSD6.0]# ifconfig wm0 inet6 febf::1 alias
[NetBSD6.0]# ifconfig wm0 inet6 febf::64/64 alias
[NetBSD6.0]# ifconfig wm0 inet6 febf::10/10 alias
[NetBSD6.0]# ifconfig wm0 inet6
wm0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
(snip)
inet6 fe80::a00:27ff:fe9a:7e50%wm0 prefixlen 64 scopeid 0x1
inet6 fe80::1%wm0 prefixlen 64 scopeid 0x1
inet6 fe80::64%wm0 prefixlen 64 scopeid 0x1
inet6 fe80::10%wm0 prefixlen 10 scopeid 0x1
inet6 febf::1%wm0 prefixlen 64 scopeid 0x1
inet6 febf::64%wm0 prefixlen 64 scopeid 0x1
inet6 febf::10%wm0 prefixlen 10 scopeid 0x1
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28. [参考] g. FreeBSD9.0
[FreeBSD9.0]# ifconfig em0 inet6
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
inet6 fe80::a00:27ff:fe26:2290%em0 prefixlen 64 scopeid 0x1
nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
[FreeBSD9.0]# ifconfig em0 inet6 fe80::1 alias
[FreeBSD9.0]# ifconfig em0 inet6 fe80::64/64 alias
[FreeBSD9.0]# ifconfig em0 inet6 fe80::10/10 alias
[FreeBSD9.0]# ifconfig em0 inet6 febf::1 alias
[FreeBSD9.0]# ifconfig em0 inet6 febf::64/64 alias
[FreeBSD9.0]# ifconfig em0 inet6 febf::10/10 alias
[FreeBSD9.0]# ifconfig em0 inet6
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
inet6 fe80::a00:27ff:fe26:2290%em0 prefixlen 64 scopeid 0x1
inet6 fe80::1%em0 prefixlen 64 scopeid 0x1
inet6 fe80::64%em0 prefixlen 64 scopeid 0x1
inet6 fe80::10%em0 prefixlen 10 scopeid 0x1
inet6 febf::1%em0 prefixlen 64 scopeid 0x1
inet6 febf::64%em0 prefixlen 64 scopeid 0x1
inet6 febf::10%em0 prefixlen 10 scopeid 0x1
nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
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29. [参考] h. OpenBSD5.1
[OpenBSD5.1]# ifconfig em0 inet6
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
(snip)
inet6 fe80::a00:27ff:fe59:ba72%em0 prefixlen 64 scopeid 0x1
[OpenBSD5.1]# ifconfig em0 inet6 fe80::1 alias
[OpenBSD5.1]# ifconfig em0 inet6 fe80::64/64 alias
[OpenBSD5.1]# ifconfig em0 inet6 fe80::10/10 alias
[OpenBSD5.1]# ifconfig em0 inet6 febf::1 alias
[OpenBSD5.1]# ifconfig em0 inet6 febf::64/64 alias
[OpenBSD5.1]# ifconfig em0 inet6 febf::10/10 alias
[OpenBSD5.1]# ifconfig em0 inet6
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
(snip)
inet6 fe80::a00:27ff:fe59:ba72%em0 prefixlen 64 scopeid 0x1
inet6 fe80::1%em0 prefixlen 64 scopeid 0x1
inet6 fe80::64%em0 prefixlen 64 scopeid 0x1
inet6 fe80::10%em0 prefixlen 10 scopeid 0x1
inet6 febf::1%em0 prefixlen 64 scopeid 0x1
inet6 febf::64%em0 prefixlen 64 scopeid 0x1
inet6 febf::10%em0 prefixlen 10 scopeid 0x1
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