DIAGRAM
NOTE
たとえばこんな構成があってsh ip bgp で確認したら
R2#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
* i 10.0.0.1/32 10.0.0.3 0 100 0 65000 i
*> 10.1.2.1 0 0 65000 i
* i 10.0.0.2/32 10.0.0.3 156160 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.0.0.3/32 10.0.0.3 0 100 0 ?
*> 10.2.3.3 156160 32768 ?
* i 10.0.0.4/32 10.0.0.3 156160 100 0 ?
*> 10.2.4.4 156160 32768 ?
* i 10.2.3.0/24 10.0.0.3 0 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.2.4.0/24 10.0.0.3 30720 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.3.4.0/24 10.0.0.3 0 100 0 ?
*> 10.2.3.3 30720 32768 ?
* i 192.168.4.0 10.0.0.3 30720 100 0 ?
*> 10.2.4.4 30720 32768 ?
R3#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
* i 10.0.0.1/32 10.0.0.2 0 100 0 65000 i
*> 10.1.3.1 0 0 65000 i
* i 10.0.0.2/32 10.0.0.2 0 100 0 ?
*> 10.2.3.2 156160 32768 ?
* i 10.0.0.3/32 10.0.0.2 156160 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.0.0.4/32 10.0.0.2 156160 100 0 ?
*> 10.3.4.4 156160 32768 ?
* i 10.2.3.0/24 10.0.0.2 0 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.2.4.0/24 10.0.0.2 0 100 0 ?
*> 10.2.3.2 30720 32768 ?
* i 10.3.4.0/24 10.0.0.2 30720 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 192.168.4.0 10.0.0.2 30720 100 0 ?
*> 10.3.4.4 30720 32768 ?
ここで192.168.0.0/16に集約して集約経路のみ広報しなさいと言われたとします。指示だけ考えれば
!!! R2,R3 router bgp 65001 agg 192.168.0.0 255.255.0.0 sum
で済みます。その後のsh ip bgpは以下です。
R2#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
* i 10.0.0.1/32 10.0.0.3 0 100 0 65000 i
*> 10.1.2.1 0 0 65000 i
* i 10.0.0.2/32 10.0.0.3 156160 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.0.0.3/32 10.0.0.3 0 100 0 ?
*> 10.2.3.3 156160 32768 ?
* i 10.0.0.4/32 10.0.0.3 156160 100 0 ?
*> 10.2.4.4 156160 32768 ?
* i 10.2.3.0/24 10.0.0.3 0 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.2.4.0/24 10.0.0.3 30720 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.3.4.0/24 10.0.0.3 0 100 0 ?
*> 10.2.3.3 30720 32768 ?
* i 192.168.0.0/16 10.0.0.3 284160 100 0 ?
*> 0.0.0.0 32768 i
s> 192.168.4.0 10.2.4.4 30720 32768 ?
R3#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
* i 10.0.0.1/32 10.0.0.2 0 100 0 65000 i
*> 10.1.3.1 0 0 65000 i
* i 10.0.0.2/32 10.0.0.2 0 100 0 ?
*> 10.2.3.2 156160 32768 ?
* i 10.0.0.3/32 10.0.0.2 156160 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.0.0.4/32 10.0.0.2 156160 100 0 ?
*> 10.3.4.4 156160 32768 ?
* i 10.2.3.0/24 10.0.0.2 0 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.2.4.0/24 10.0.0.2 0 100 0 ?
*> 10.2.3.2 30720 32768 ?
* i 10.3.4.0/24 10.0.0.2 30720 100 0 ?
*> 0.0.0.0 0 32768 ?
* 192.168.0.0/16 0.0.0.0 32768 i
*> 10.2.3.2 284160 32768 ?
* i 10.0.0.2 0 100 0 i
s> 192.168.4.0 10.3.4.4 30720 32768 ?
やっぱり/16の部分が気になります。R2は自分で集約生成したものとiBGPで受けたものだけ。R2/R3は冗長構成になっているので期待としては同じエントリ数になるはずがR3では3つある。しかもR3にしかないものがベスト。? があるのでincompleteで、Next HopアドレスがR2-R3のアドレスなのでR2からのEIGRP経路の再配送であることが分かります。
ちなみにR1で/16の見え方は
* 192.168.0.0/16 10.1.3.3 284160 0 65001 ? *> 10.1.2.2 0 0 65001 i
これはこれで要件に影響がなければこのままもいいかもしれませんが、やはり気付いてしまった以上は何とかしたくなります。
!!! R2,R3 ip prefix REDIST-ROUTE s 10 deny 192.168.0.0/16 ip prefix REDIST-ROUTE s 100 per 0.0.0.0/0 le 32 route-map BGP-INTO-EIGRP per 10 match ip add prefix REDIST-ROUTE router ei 65001 redist bgp 65001 metric 100000 10 255 1 1500 route-map BGP-INTO-EIGRP
追加設定後のsh ip bgp
R2#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
* i 10.0.0.1/32 10.0.0.3 0 100 0 65000 i
*> 10.1.2.1 0 0 65000 i
* i 10.0.0.2/32 10.0.0.3 156160 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.0.0.3/32 10.0.0.3 0 100 0 ?
*> 10.2.3.3 156160 32768 ?
* i 10.0.0.4/32 10.0.0.3 156160 100 0 ?
*> 10.2.4.4 156160 32768 ?
* i 10.2.3.0/24 10.0.0.3 0 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.2.4.0/24 10.0.0.3 30720 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.3.4.0/24 10.0.0.3 0 100 0 ?
*> 10.2.3.3 30720 32768 ?
* i 192.168.0.0/16 10.0.0.3 0 100 0 i
*> 0.0.0.0 32768 i
s> 192.168.4.0 10.2.4.4 30720 32768 ?
R3#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
* i 10.0.0.1/32 10.0.0.2 0 100 0 65000 i
*> 10.1.3.1 0 0 65000 i
* i 10.0.0.2/32 10.0.0.2 0 100 0 ?
*> 10.2.3.2 156160 32768 ?
* i 10.0.0.3/32 10.0.0.2 156160 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.0.0.4/32 10.0.0.2 156160 100 0 ?
*> 10.3.4.4 156160 32768 ?
* i 10.2.3.0/24 10.0.0.2 0 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.2.4.0/24 10.0.0.2 0 100 0 ?
*> 10.2.3.2 30720 32768 ?
* i 10.3.4.0/24 10.0.0.2 30720 100 0 ?
*> 0.0.0.0 0 32768 ?
*> 192.168.0.0/16 0.0.0.0 32768 i
* i 10.0.0.2 0 100 0 i
s> 192.168.4.0 10.3.4.4 30720 32768 ?
R1の見え方
*> 192.168.0.0/16 10.1.3.3 0 0 65001 i * 10.1.2.2 0 0 65001 i
問題の指示には無くても、他で追加設定が発生しないかを忘れずに意識したいところです。
CONFIGURATION
hostname R1 ! interface Loopback0 ip address 10.0.0.1 255.255.255.255 ! interface FastEthernet0/0 ip address 10.1.2.1 255.255.255.0 no shutdown ! interface FastEthernet1/0 ip address 10.1.3.1 255.255.255.0 no shutdown ! router bgp 65000 bgp router-id 10.0.0.1 network 10.0.0.1 mask 255.255.255.255 neighbor 10.1.2.2 remote-as 65001 neighbor 10.1.3.3 remote-as 65001 ! end
hostname R2 ! interface Loopback0 ip address 10.0.0.2 255.255.255.255 ! interface FastEthernet0/0 ip address 10.1.2.2 255.255.255.0 no shutdown ! interface FastEthernet1/0 ip address 10.2.4.2 255.255.255.0 no shutdown ! interface FastEthernet2/0 ip address 10.2.3.2 255.255.255.0 no shutdown ! router eigrp 65001 network 10.0.0.2 0.0.0.0 network 10.2.3.2 0.0.0.0 network 10.2.4.2 0.0.0.0 redistribute bgp 65001 metric 10000 100 255 1 1500 eigrp router-id 10.0.0.2 ! router bgp 65001 bgp router-id 10.0.0.2 redistribute eigrp 65001 neighbor 10.0.0.3 remote-as 65001 neighbor 10.0.0.3 update-source Loopback0 neighbor 10.0.0.3 next-hop-self neighbor 10.1.2.1 remote-as 65000 ! end
hostname R3 ! interface Loopback0 ip address 10.0.0.3 255.255.255.255 ! interface FastEthernet0/0 ip address 10.1.3.3 255.255.255.0 no shutdown ! interface FastEthernet1/0 ip address 10.3.4.3 255.255.255.0 no shutdown ! interface FastEthernet2/0 ip address 10.2.3.3 255.255.255.0 no shutdown ! router eigrp 65001 network 10.0.0.3 0.0.0.0 network 10.2.3.3 0.0.0.0 network 10.3.4.3 0.0.0.0 redistribute bgp 65001 metric 10000 100 255 1 1500 eigrp router-id 10.0.0.3 ! router bgp 65001 bgp router-id 10.0.0.3 redistribute eigrp 65001 neighbor 10.0.0.2 remote-as 65001 neighbor 10.0.0.2 update-source Loopback0 neighbor 10.0.0.2 next-hop-self neighbor 10.1.3.1 remote-as 65000 ! end
hostname R4 ! interface Loopback0 ip address 10.0.0.4 255.255.255.255 ! interface FastEthernet0/0 ip address 10.2.4.4 255.255.255.0 no shutdown ! interface FastEthernet1/0 ip address 10.3.4.4 255.255.255.0 no shutdown ! interface FastEthernet2/0 ip address 192.168.4.4 255.255.255.0 no shutdown ! router eigrp 65001 network 10.0.0.4 0.0.0.0 network 10.2.4.4 0.0.0.0 network 10.3.4.4 0.0.0.0 network 192.168.4.4 0.0.0.0 eigrp router-id 10.0.0.4 ! end
コメント