勉強日記

チラ裏

CCNA試験対策 ch25 Implementing IPv6 Routing

CCNA ネットワーク 勉強メモ

Connected and Local IPv6 Routes

R1#show ipv6 route
IPv6 Routing Table - 5 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
       U - Per-user Static route, M - MIPv6
       I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
       O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
       D - EIGRP, EX - EIGRP external
C   2001:DB8:1111:1::/64 [0/0]
     via GigabitEthernet0/0/0, directly connected
L   2001:DB8:1111:1::1/128 [0/0]
     via GigabitEthernet0/0/0, receive
C   2001:DB8:1111:4::/64 [0/0]
     via GigabitEthernet0/0/1, directly connected
L   2001:DB8:1111:4::1/128 [0/0]
     via GigabitEthernet0/0/1, receive
L   FF00::/8 [0/0]
     via Null0, receive
R1#

Static IPv6 Routes

f:id:wand_ta:20200506234244p:plain

R1#show ipv6 interface g0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::2D0:BAFF:FE39:501
  No Virtual link-local address(es):
  Global unicast address(es):
    2001:DB8:1111:1::1, subnet is 2001:DB8:1111:1::/64
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::1:FF00:1
    FF02::1:FF39:501
  MTU is 1500 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  ICMP unreachables are sent
  ND DAD is enabled, number of DAD attempts: 1
  ND reachable time is 30000 milliseconds
  ND advertised reachable time is 0 (unspecified)
  ND advertised retransmit interval is 0 (unspecified)
  ND router advertisements are sent every 200 seconds
  ND router advertisements live for 1800 seconds
  ND advertised default router preference is Medium
  Hosts use stateless autoconfig for addresses.
R1#

f:id:wand_ta:20200506234128p:plain

f:id:wand_ta:20200506234135p:plain

on PC0:

C:\>ping 2001:DB8:1111:1::1

Pinging 2001:DB8:1111:1::1 with 32 bytes of data:

Reply from 2001:DB8:1111:1::1: bytes=32 time<1ms TTL=255
Reply from 2001:DB8:1111:1::1: bytes=32 time=1ms TTL=255
Reply from 2001:DB8:1111:1::1: bytes=32 time<1ms TTL=255
Reply from 2001:DB8:1111:1::1: bytes=32 time=1ms TTL=255

Ping statistics for 2001:DB8:1111:1::1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 1ms, Average = 0ms
  • R2,PC1も同様に設定する
  • R1->R2 ping
R1#ping 2001:DB8:1111:2::1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:1111:2::1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

R1#
  • routingが設定されていないので当然疎通しない
  • R1のroutingを設定する必要がある

Static Routes Using the Outgoing Interface

  • 次のように設定するやつ
R1(config)#ipv6 route 2001:db8:1111:2::/64 s0/1
  • serialでのみ動く
    • ethernet interfaceではIPv6 addressの指定が必要 (後述)

Static Routes Using Next-Hop IPv6 Address

R1(config)#ipv6 route 2001:db8:1111:2::/64 2001:db8:1111:4::2
R1(config)#end
R1#
%SYS-5-CONFIG_I: Configured from console by console
R1#show ipv6 route 
IPv6 Routing Table - 6 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
       U - Per-user Static route, M - MIPv6
       I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
       O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
       D - EIGRP, EX - EIGRP external
C   2001:DB8:1111:1::/64 [0/0]
     via GigabitEthernet0/0/0, directly connected
L   2001:DB8:1111:1::1/128 [0/0]
     via GigabitEthernet0/0/0, receive
S   2001:DB8:1111:2::/64 [1/0]
     via 2001:DB8:1111:4::2
C   2001:DB8:1111:4::/64 [0/0]
     via GigabitEthernet0/0/1, directly connected
L   2001:DB8:1111:4::1/128 [0/0]
     via GigabitEthernet0/0/1, receive
L   FF00::/8 [0/0]
     via Null0, receive
R1#
  • R2も同様に設定する
  • from 2001:db8:1111:1::11
C:\>ping 2001:db8:1111:2::11

Pinging 2001:db8:1111:2::11 with 32 bytes of data:

Reply from 2001:DB8:1111:2::11: bytes=32 time<1ms TTL=126
Reply from 2001:DB8:1111:2::11: bytes=32 time<1ms TTL=126
Reply from 2001:DB8:1111:2::11: bytes=32 time<1ms TTL=126
Reply from 2001:DB8:1111:2::11: bytes=32 time<1ms TTL=126

Ping statistics for 2001:DB8:1111:2::11:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms
  • link local addressを指定する場合は、outgoing interfaceの指定が必要
R1(config)#no ipv6 route 2001:db8:1111:2::/64
R1(config)#ipv6 route 2001:db8:1111:2::/64 g0/0/1 FE80::210:11FF:FED5:5702
R1#show ipv6 route
IPv6 Routing Table - 6 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
       U - Per-user Static route, M - MIPv6
       I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
       O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
       D - EIGRP, EX - EIGRP external
C   2001:DB8:1111:1::/64 [0/0]
     via GigabitEthernet0/0/0, directly connected
L   2001:DB8:1111:1::1/128 [0/0]
     via GigabitEthernet0/0/0, receive
S   2001:DB8:1111:2::/64 [1/0]
     via FE80::210:11FF:FED5:5702, GigabitEthernet0/0/1
C   2001:DB8:1111:4::/64 [0/0]
     via GigabitEthernet0/0/1, directly connected
L   2001:DB8:1111:4::1/128 [0/0]
     via GigabitEthernet0/0/1, receive
L   FF00::/8 [0/0]
     via Null0, receive
R1#
  • outgoint interface + unicast address でもよいが冗長

Static Default Routes

  • last resort route的なやつ
  • ::/0

Sttaic IPv6 Host Routes

  • destinationをsubnetではなく/128まで指定するやつ

Floating Static Ipv6 Routes

  • static route、各種routing protocol等を併用するさい、AD: administrative distance に基づいて優先度が変わるやつ
  • 小さいもの優先n
  • デフォルト値
Route Source Administrative Distance
Connected routes 0
Static routes 1
NDP 2
EIGRP 90
OSPF 110
RIP 120
unknown or unbelievable 255

The Neighbor Discovery Protocol

  • IPv4のARPに相当
  • NS: Neighbor Solicitation
    • MACアドレスの問い合わせ
    • solicited-node multicast addressに送信される
      • つまり、リンクローカルで、16進表記で末尾6文字が一致するホストにのみ問い合わせる
      • 無差別に送りつけないということ
  • NA: Neighbor Advertisement

Discovering Routers with NDP RS and RA

  • RS: Router Solicitation
    • 「全IPv6ルーター」のlocal-scope multi-cast addressに問い合わせ
      • FF02::2
  • RA: Router Advertisement
    • IPv6 link local addressを返信、もしくは全IPv6ホスト(FF02::1)に送信する

Using SLAAC with NDP RS and RA

  • SLAAC: Stateless Address Autoconfiguration
  • DHCPと異なり、サーバーが不要なのが特徴
    • state = address poolが要らないということ
  • 処理の流れ
    1. NDP RAメッセージを用いてIPv6アドレスのPrefix部を取得する
    2. 各hostでInterface ID部を生成する
      • EUI-64 または乱数
    3. PrefixとInterface IDでIPv6アドレスを組み立てる
    4. IPv6アドレスを使用する前に、DAD: Duplicate Address Detection で重複のなきことを確認する

Discovering Dupliate Addresses Using NDP NS and NA

  • DAD: Duplicate Address Detection
  • 自分のIPv6アドレスでNSメッセージを送信する
  • NAレスポンスが帰ってきたら、IPv6アドレスが重複しているということ

NDP Summary

Protocol Message Who Discovers Info Who Supplies Info Info
RS/RA Any IPv6 host Any IPv6 router 各Routerのリンクローカルアドレス
RS/RA Any IPv6 host Any IPv6 router ローカルリンクのPrefix/length
NS/NA Any IPv6 host Any IPv6 host 隣接ホストのMACアドレス
NS/NA Any IPv6 host Any IPv6 host IPv6アドレスの重複