助け合いフォーラム

Cisco

CCNP ENARSI(300-410)
問題ID : 25513
問題を開く
RCのルーティングテーブルに載る情報はどれか（3つ選択）

この問題はプレミアムコンテンツです。

上に戻る

EIGRPの経路集約について

3 3yamot
公開日 2023/09/12

解説の文中に「EIGRPの自動集約を行うのはクラスフルの境界になっているルータ」とあるのですが、
問題の中で扱っているIPアドレスは全て「172.XX.1.0」で、全てクラスBに属しているように思えます。

（クラスフルアドレスの場合、以下のようにクラス分けされている認識です。）
クラスA：0.0.0.0～127.255.255.255　/8
クラスB：128.0.0.0～191.255.255.255 /16
クラスC：192.0.0.0～223.255.255.255 /24

このため、「クラスフルの境界」という表現が理解できずにいるのですが、これはどのように考えればよろしいのでしょうか？

程度の低い質問で恐縮ですが、どなたかご教示いただけますと幸いです。
よろしくお願いします。

a arashi1977
2023/09/12 11:51

書かれてる通りですが、クラスBは「/16」なのでそこで見る必要があります。

（クラスフルアドレスの場合、以下のようにクラス分けされている認識です。）
クラスA：0.0.0.0～127.255.255.255　/8
クラスB：128.0.0.0～191.255.255.255 /16

例えば

  • 172.16.1.0/24のクラスフルメジャーネットワークは172.16.0.0/16
  • 172.16.2.0/24のクラスフルメジャーネットワークは172.16.0.0/16
  • 172.17.1.0/24のクラスフルメジャーネットワークは172.17.0.0/16

って感じです。

実物で見るとこんな感じです。めっちゃ長いので目が滑りそうですが。
まず、172.[16-31].[0-9].1/24なアドレスを割り当てたLoopbackインターフェースを作った時のルーティングテーブルです。variably subnettedと表示されてる行がクラスフルメジャーネットワークが確認できるところです（目印つけてます）。

Router#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is not set

      172.16.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.16.0.0/24 is directly connected, Loopback16
L        172.16.0.1/32 is directly connected, Loopback16
C        172.16.1.0/24 is directly connected, Loopback1016
L        172.16.1.1/32 is directly connected, Loopback1016
C        172.16.2.0/24 is directly connected, Loopback2016
L        172.16.2.1/32 is directly connected, Loopback2016
C        172.16.3.0/24 is directly connected, Loopback3016
L        172.16.3.1/32 is directly connected, Loopback3016
C        172.16.4.0/24 is directly connected, Loopback4016
L        172.16.4.1/32 is directly connected, Loopback4016
C        172.16.5.0/24 is directly connected, Loopback5016
L        172.16.5.1/32 is directly connected, Loopback5016
C        172.16.6.0/24 is directly connected, Loopback6016
L        172.16.6.1/32 is directly connected, Loopback6016
C        172.16.7.0/24 is directly connected, Loopback7016
L        172.16.7.1/32 is directly connected, Loopback7016
C        172.16.8.0/24 is directly connected, Loopback8016
L        172.16.8.1/32 is directly connected, Loopback8016
C        172.16.9.0/24 is directly connected, Loopback9016
L        172.16.9.1/32 is directly connected, Loopback9016
      172.17.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.17.0.0/24 is directly connected, Loopback17
L        172.17.0.1/32 is directly connected, Loopback17
C        172.17.1.0/24 is directly connected, Loopback1017
L        172.17.1.1/32 is directly connected, Loopback1017
C        172.17.2.0/24 is directly connected, Loopback2017
L        172.17.2.1/32 is directly connected, Loopback2017
C        172.17.3.0/24 is directly connected, Loopback3017
L        172.17.3.1/32 is directly connected, Loopback3017
C        172.17.4.0/24 is directly connected, Loopback4017
L        172.17.4.1/32 is directly connected, Loopback4017
C        172.17.5.0/24 is directly connected, Loopback5017
L        172.17.5.1/32 is directly connected, Loopback5017
C        172.17.6.0/24 is directly connected, Loopback6017
L        172.17.6.1/32 is directly connected, Loopback6017
C        172.17.7.0/24 is directly connected, Loopback7017
L        172.17.7.1/32 is directly connected, Loopback7017
C        172.17.8.0/24 is directly connected, Loopback8017
L        172.17.8.1/32 is directly connected, Loopback8017
C        172.17.9.0/24 is directly connected, Loopback9017
L        172.17.9.1/32 is directly connected, Loopback9017
      172.18.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.18.0.0/24 is directly connected, Loopback18
L        172.18.0.1/32 is directly connected, Loopback18
C        172.18.1.0/24 is directly connected, Loopback1018
L        172.18.1.1/32 is directly connected, Loopback1018
C        172.18.2.0/24 is directly connected, Loopback2018
L        172.18.2.1/32 is directly connected, Loopback2018
C        172.18.3.0/24 is directly connected, Loopback3018
L        172.18.3.1/32 is directly connected, Loopback3018
C        172.18.4.0/24 is directly connected, Loopback4018
L        172.18.4.1/32 is directly connected, Loopback4018
C        172.18.5.0/24 is directly connected, Loopback5018
L        172.18.5.1/32 is directly connected, Loopback5018
C        172.18.6.0/24 is directly connected, Loopback6018
L        172.18.6.1/32 is directly connected, Loopback6018
C        172.18.7.0/24 is directly connected, Loopback7018
L        172.18.7.1/32 is directly connected, Loopback7018
C        172.18.8.0/24 is directly connected, Loopback8018
L        172.18.8.1/32 is directly connected, Loopback8018
C        172.18.9.0/24 is directly connected, Loopback9018
L        172.18.9.1/32 is directly connected, Loopback9018
      172.19.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.19.0.0/24 is directly connected, Loopback19
L        172.19.0.1/32 is directly connected, Loopback19
C        172.19.1.0/24 is directly connected, Loopback1019
L        172.19.1.1/32 is directly connected, Loopback1019
C        172.19.2.0/24 is directly connected, Loopback2019
L        172.19.2.1/32 is directly connected, Loopback2019
C        172.19.3.0/24 is directly connected, Loopback3019
L        172.19.3.1/32 is directly connected, Loopback3019
C        172.19.4.0/24 is directly connected, Loopback4019
L        172.19.4.1/32 is directly connected, Loopback4019
C        172.19.5.0/24 is directly connected, Loopback5019
L        172.19.5.1/32 is directly connected, Loopback5019
C        172.19.6.0/24 is directly connected, Loopback6019
L        172.19.6.1/32 is directly connected, Loopback6019
C        172.19.7.0/24 is directly connected, Loopback7019
L        172.19.7.1/32 is directly connected, Loopback7019
C        172.19.8.0/24 is directly connected, Loopback8019
L        172.19.8.1/32 is directly connected, Loopback8019
C        172.19.9.0/24 is directly connected, Loopback9019
L        172.19.9.1/32 is directly connected, Loopback9019
      172.20.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.20.0.0/24 is directly connected, Loopback20
L        172.20.0.1/32 is directly connected, Loopback20
C        172.20.1.0/24 is directly connected, Loopback1020
L        172.20.1.1/32 is directly connected, Loopback1020
C        172.20.2.0/24 is directly connected, Loopback2020
L        172.20.2.1/32 is directly connected, Loopback2020
C        172.20.3.0/24 is directly connected, Loopback3020
L        172.20.3.1/32 is directly connected, Loopback3020
C        172.20.4.0/24 is directly connected, Loopback4020
L        172.20.4.1/32 is directly connected, Loopback4020
C        172.20.5.0/24 is directly connected, Loopback5020
L        172.20.5.1/32 is directly connected, Loopback5020
C        172.20.6.0/24 is directly connected, Loopback6020
L        172.20.6.1/32 is directly connected, Loopback6020
C        172.20.7.0/24 is directly connected, Loopback7020
L        172.20.7.1/32 is directly connected, Loopback7020
C        172.20.8.0/24 is directly connected, Loopback8020
L        172.20.8.1/32 is directly connected, Loopback8020
C        172.20.9.0/24 is directly connected, Loopback9020
L        172.20.9.1/32 is directly connected, Loopback9020
      172.21.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.21.0.0/24 is directly connected, Loopback21
L        172.21.0.1/32 is directly connected, Loopback21
C        172.21.1.0/24 is directly connected, Loopback1021
L        172.21.1.1/32 is directly connected, Loopback1021
C        172.21.2.0/24 is directly connected, Loopback2021
L        172.21.2.1/32 is directly connected, Loopback2021
C        172.21.3.0/24 is directly connected, Loopback3021
L        172.21.3.1/32 is directly connected, Loopback3021
C        172.21.4.0/24 is directly connected, Loopback4021
L        172.21.4.1/32 is directly connected, Loopback4021
C        172.21.5.0/24 is directly connected, Loopback5021
L        172.21.5.1/32 is directly connected, Loopback5021
C        172.21.6.0/24 is directly connected, Loopback6021
L        172.21.6.1/32 is directly connected, Loopback6021
C        172.21.7.0/24 is directly connected, Loopback7021
L        172.21.7.1/32 is directly connected, Loopback7021
C        172.21.8.0/24 is directly connected, Loopback8021
L        172.21.8.1/32 is directly connected, Loopback8021
C        172.21.9.0/24 is directly connected, Loopback9021
L        172.21.9.1/32 is directly connected, Loopback9021
      172.22.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.22.0.0/24 is directly connected, Loopback22
L        172.22.0.1/32 is directly connected, Loopback22
C        172.22.1.0/24 is directly connected, Loopback1022
L        172.22.1.1/32 is directly connected, Loopback1022
C        172.22.2.0/24 is directly connected, Loopback2022
L        172.22.2.1/32 is directly connected, Loopback2022
C        172.22.3.0/24 is directly connected, Loopback3022
L        172.22.3.1/32 is directly connected, Loopback3022
C        172.22.4.0/24 is directly connected, Loopback4022
L        172.22.4.1/32 is directly connected, Loopback4022
C        172.22.5.0/24 is directly connected, Loopback5022
L        172.22.5.1/32 is directly connected, Loopback5022
C        172.22.6.0/24 is directly connected, Loopback6022
L        172.22.6.1/32 is directly connected, Loopback6022
C        172.22.7.0/24 is directly connected, Loopback7022
L        172.22.7.1/32 is directly connected, Loopback7022
C        172.22.8.0/24 is directly connected, Loopback8022
L        172.22.8.1/32 is directly connected, Loopback8022
C        172.22.9.0/24 is directly connected, Loopback9022
L        172.22.9.1/32 is directly connected, Loopback9022
      172.23.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.23.0.0/24 is directly connected, Loopback23
L        172.23.0.1/32 is directly connected, Loopback23
C        172.23.1.0/24 is directly connected, Loopback1023
L        172.23.1.1/32 is directly connected, Loopback1023
C        172.23.2.0/24 is directly connected, Loopback2023
L        172.23.2.1/32 is directly connected, Loopback2023
C        172.23.3.0/24 is directly connected, Loopback3023
L        172.23.3.1/32 is directly connected, Loopback3023
C        172.23.4.0/24 is directly connected, Loopback4023
L        172.23.4.1/32 is directly connected, Loopback4023
C        172.23.5.0/24 is directly connected, Loopback5023
L        172.23.5.1/32 is directly connected, Loopback5023
C        172.23.6.0/24 is directly connected, Loopback6023
L        172.23.6.1/32 is directly connected, Loopback6023
C        172.23.7.0/24 is directly connected, Loopback7023
L        172.23.7.1/32 is directly connected, Loopback7023
C        172.23.8.0/24 is directly connected, Loopback8023
L        172.23.8.1/32 is directly connected, Loopback8023
C        172.23.9.0/24 is directly connected, Loopback9023
L        172.23.9.1/32 is directly connected, Loopback9023
      172.24.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.24.0.0/24 is directly connected, Loopback24
L        172.24.0.1/32 is directly connected, Loopback24
C        172.24.1.0/24 is directly connected, Loopback1024
L        172.24.1.1/32 is directly connected, Loopback1024
C        172.24.2.0/24 is directly connected, Loopback2024
L        172.24.2.1/32 is directly connected, Loopback2024
C        172.24.3.0/24 is directly connected, Loopback3024
L        172.24.3.1/32 is directly connected, Loopback3024
C        172.24.4.0/24 is directly connected, Loopback4024
L        172.24.4.1/32 is directly connected, Loopback4024
C        172.24.5.0/24 is directly connected, Loopback5024
L        172.24.5.1/32 is directly connected, Loopback5024
C        172.24.6.0/24 is directly connected, Loopback6024
L        172.24.6.1/32 is directly connected, Loopback6024
C        172.24.7.0/24 is directly connected, Loopback7024
L        172.24.7.1/32 is directly connected, Loopback7024
C        172.24.8.0/24 is directly connected, Loopback8024
L        172.24.8.1/32 is directly connected, Loopback8024
C        172.24.9.0/24 is directly connected, Loopback9024
L        172.24.9.1/32 is directly connected, Loopback9024
      172.25.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.25.0.0/24 is directly connected, Loopback25
L        172.25.0.1/32 is directly connected, Loopback25
C        172.25.1.0/24 is directly connected, Loopback1025
L        172.25.1.1/32 is directly connected, Loopback1025
C        172.25.2.0/24 is directly connected, Loopback2025
L        172.25.2.1/32 is directly connected, Loopback2025
C        172.25.3.0/24 is directly connected, Loopback3025
L        172.25.3.1/32 is directly connected, Loopback3025
C        172.25.4.0/24 is directly connected, Loopback4025
L        172.25.4.1/32 is directly connected, Loopback4025
C        172.25.5.0/24 is directly connected, Loopback5025
L        172.25.5.1/32 is directly connected, Loopback5025
C        172.25.6.0/24 is directly connected, Loopback6025
L        172.25.6.1/32 is directly connected, Loopback6025
C        172.25.7.0/24 is directly connected, Loopback7025
L        172.25.7.1/32 is directly connected, Loopback7025
C        172.25.8.0/24 is directly connected, Loopback8025
L        172.25.8.1/32 is directly connected, Loopback8025
C        172.25.9.0/24 is directly connected, Loopback9025
L        172.25.9.1/32 is directly connected, Loopback9025
      172.26.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.26.0.0/24 is directly connected, Loopback26
L        172.26.0.1/32 is directly connected, Loopback26
C        172.26.1.0/24 is directly connected, Loopback1026
L        172.26.1.1/32 is directly connected, Loopback1026
C        172.26.2.0/24 is directly connected, Loopback2026
L        172.26.2.1/32 is directly connected, Loopback2026
C        172.26.3.0/24 is directly connected, Loopback3026
L        172.26.3.1/32 is directly connected, Loopback3026
C        172.26.4.0/24 is directly connected, Loopback4026
L        172.26.4.1/32 is directly connected, Loopback4026
C        172.26.5.0/24 is directly connected, Loopback5026
L        172.26.5.1/32 is directly connected, Loopback5026
C        172.26.6.0/24 is directly connected, Loopback6026
L        172.26.6.1/32 is directly connected, Loopback6026
C        172.26.7.0/24 is directly connected, Loopback7026
L        172.26.7.1/32 is directly connected, Loopback7026
C        172.26.8.0/24 is directly connected, Loopback8026
L        172.26.8.1/32 is directly connected, Loopback8026
C        172.26.9.0/24 is directly connected, Loopback9026
L        172.26.9.1/32 is directly connected, Loopback9026
      172.27.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.27.0.0/24 is directly connected, Loopback27
L        172.27.0.1/32 is directly connected, Loopback27
C        172.27.1.0/24 is directly connected, Loopback1027
L        172.27.1.1/32 is directly connected, Loopback1027
C        172.27.2.0/24 is directly connected, Loopback2027
L        172.27.2.1/32 is directly connected, Loopback2027
C        172.27.3.0/24 is directly connected, Loopback3027
L        172.27.3.1/32 is directly connected, Loopback3027
C        172.27.4.0/24 is directly connected, Loopback4027
L        172.27.4.1/32 is directly connected, Loopback4027
C        172.27.5.0/24 is directly connected, Loopback5027
L        172.27.5.1/32 is directly connected, Loopback5027
C        172.27.6.0/24 is directly connected, Loopback6027
L        172.27.6.1/32 is directly connected, Loopback6027
C        172.27.7.0/24 is directly connected, Loopback7027
L        172.27.7.1/32 is directly connected, Loopback7027
C        172.27.8.0/24 is directly connected, Loopback8027
L        172.27.8.1/32 is directly connected, Loopback8027
C        172.27.9.0/24 is directly connected, Loopback9027
L        172.27.9.1/32 is directly connected, Loopback9027
      172.28.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.28.0.0/24 is directly connected, Loopback28
L        172.28.0.1/32 is directly connected, Loopback28
C        172.28.1.0/24 is directly connected, Loopback1028
L        172.28.1.1/32 is directly connected, Loopback1028
C        172.28.2.0/24 is directly connected, Loopback2028
L        172.28.2.1/32 is directly connected, Loopback2028
C        172.28.3.0/24 is directly connected, Loopback3028
L        172.28.3.1/32 is directly connected, Loopback3028
C        172.28.4.0/24 is directly connected, Loopback4028
L        172.28.4.1/32 is directly connected, Loopback4028
C        172.28.5.0/24 is directly connected, Loopback5028
L        172.28.5.1/32 is directly connected, Loopback5028
C        172.28.6.0/24 is directly connected, Loopback6028
L        172.28.6.1/32 is directly connected, Loopback6028
C        172.28.7.0/24 is directly connected, Loopback7028
L        172.28.7.1/32 is directly connected, Loopback7028
C        172.28.8.0/24 is directly connected, Loopback8028
L        172.28.8.1/32 is directly connected, Loopback8028
C        172.28.9.0/24 is directly connected, Loopback9028
L        172.28.9.1/32 is directly connected, Loopback9028
      172.29.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.29.0.0/24 is directly connected, Loopback29
L        172.29.0.1/32 is directly connected, Loopback29
C        172.29.1.0/24 is directly connected, Loopback1029
L        172.29.1.1/32 is directly connected, Loopback1029
C        172.29.2.0/24 is directly connected, Loopback2029
L        172.29.2.1/32 is directly connected, Loopback2029
C        172.29.3.0/24 is directly connected, Loopback3029
L        172.29.3.1/32 is directly connected, Loopback3029
C        172.29.4.0/24 is directly connected, Loopback4029
L        172.29.4.1/32 is directly connected, Loopback4029
C        172.29.5.0/24 is directly connected, Loopback5029
L        172.29.5.1/32 is directly connected, Loopback5029
C        172.29.6.0/24 is directly connected, Loopback6029
L        172.29.6.1/32 is directly connected, Loopback6029
C        172.29.7.0/24 is directly connected, Loopback7029
L        172.29.7.1/32 is directly connected, Loopback7029
C        172.29.8.0/24 is directly connected, Loopback8029
L        172.29.8.1/32 is directly connected, Loopback8029
C        172.29.9.0/24 is directly connected, Loopback9029
L        172.29.9.1/32 is directly connected, Loopback9029
      172.30.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.30.0.0/24 is directly connected, Loopback30
L        172.30.0.1/32 is directly connected, Loopback30
C        172.30.1.0/24 is directly connected, Loopback1030
L        172.30.1.1/32 is directly connected, Loopback1030
C        172.30.2.0/24 is directly connected, Loopback2030
L        172.30.2.1/32 is directly connected, Loopback2030
C        172.30.3.0/24 is directly connected, Loopback3030
L        172.30.3.1/32 is directly connected, Loopback3030
C        172.30.4.0/24 is directly connected, Loopback4030
L        172.30.4.1/32 is directly connected, Loopback4030
C        172.30.5.0/24 is directly connected, Loopback5030
L        172.30.5.1/32 is directly connected, Loopback5030
C        172.30.6.0/24 is directly connected, Loopback6030
L        172.30.6.1/32 is directly connected, Loopback6030
C        172.30.7.0/24 is directly connected, Loopback7030
L        172.30.7.1/32 is directly connected, Loopback7030
C        172.30.8.0/24 is directly connected, Loopback8030
L        172.30.8.1/32 is directly connected, Loopback8030
C        172.30.9.0/24 is directly connected, Loopback9030
L        172.30.9.1/32 is directly connected, Loopback9030
      172.31.0.0/16 is variably subnetted, 20 subnets, 2 masks　←ここ
C        172.31.0.0/24 is directly connected, Loopback31
L        172.31.0.1/32 is directly connected, Loopback31
C        172.31.1.0/24 is directly connected, Loopback1031
L        172.31.1.1/32 is directly connected, Loopback1031
C        172.31.2.0/24 is directly connected, Loopback2031
L        172.31.2.1/32 is directly connected, Loopback2031
C        172.31.3.0/24 is directly connected, Loopback3031
L        172.31.3.1/32 is directly connected, Loopback3031
C        172.31.4.0/24 is directly connected, Loopback4031
L        172.31.4.1/32 is directly connected, Loopback4031
C        172.31.5.0/24 is directly connected, Loopback5031
L        172.31.5.1/32 is directly connected, Loopback5031
C        172.31.6.0/24 is directly connected, Loopback6031
L        172.31.6.1/32 is directly connected, Loopback6031
C        172.31.7.0/24 is directly connected, Loopback7031
L        172.31.7.1/32 is directly connected, Loopback7031
C        172.31.8.0/24 is directly connected, Loopback8031
L        172.31.8.1/32 is directly connected, Loopback8031
C        172.31.9.0/24 is directly connected, Loopback9031
L        172.31.9.1/32 is directly connected, Loopback9031

この環境で自動集約有効にしたEIGRPを設定してみます。

Router#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#router eigrp 1
Router(config-router)#net 172.0.0.0 0.255.255.255
Router(config-router)#auto-summary
Router(config-router)#end
Router#

そうすると、集約ルートが出来上がりますが、これが上記のvariably subnettedと同じになることが確認できます。（みやすさのために出力をフィルタしてます）

Router#show ip route | i Null0|variably subnetted
      172.16.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.16.0.0/16 is a summary, 00:01:38, Null0
      172.17.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.17.0.0/16 is a summary, 00:01:38, Null0
      172.18.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.18.0.0/16 is a summary, 00:01:38, Null0
      172.19.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.19.0.0/16 is a summary, 00:01:38, Null0
      172.20.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.20.0.0/16 is a summary, 00:01:38, Null0
      172.21.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.21.0.0/16 is a summary, 00:01:38, Null0
      172.22.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.22.0.0/16 is a summary, 00:01:38, Null0
      172.23.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.23.0.0/16 is a summary, 00:01:38, Null0
      172.24.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.24.0.0/16 is a summary, 00:01:38, Null0
      172.25.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.25.0.0/16 is a summary, 00:01:38, Null0
      172.26.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.26.0.0/16 is a summary, 00:01:38, Null0
      172.27.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.27.0.0/16 is a summary, 00:01:38, Null0
      172.28.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.28.0.0/16 is a summary, 00:01:38, Null0
      172.29.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.29.0.0/16 is a summary, 00:01:38, Null0
      172.30.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.30.0.0/16 is a summary, 00:01:38, Null0
      172.31.0.0/16 is variably subnetted, 21 subnets, 3 masks
D        172.31.0.0/16 is a summary, 00:01:38, Null0

コメント

3 3yamot

2023/09/14 07:39

返答遅くなりすみません。 ご丁寧にルーティングテーブルまで見せていただき、本当にありがとうございます！ クラスごとのサブネットマスクのネットワーク部のみに注目して、自動集約が行われると理解しました。 （ネットワーク部の範囲が、クラスAであれば/8,クラスBであれば/16,クラスCであれば/24） 自動集約への理解が進んで勉強へのモチベーションが上がりました！ 本当にありがとうございます！

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