例えば、VRF-Lite でネットワークを分離したとして、共通でアクセスする必要があるサービスがいくつかあります。仮想ネットワーク毎にサービスを用意するのは、費用的な問題等、現実的ではない場合があります。
Cisco の Route Replication は、異なる VRF の RIB*1を相互にコピーします。これにより、複雑なルートマージなしに、別の仮想ネットワークへ到達する事が可能となります。
上図は、ASR1001 を Fusion Point*2とした場合の Route Replication のイメージになります。
USER-A, USER-B, USER-C は、それぞれ SERVICES のネットワーク：172.16.1.0/24 の情報を持ちます。SERVICES では、USER-A, USER-B, USER-C の情報を持ちません。各ネットワークが重複しているためです。
SERVICES から、USER-A, USER-B, USER-C への通信については、NAT を使用して、到達性を確保します。
Route Replication 設定例
設定は下記のとおり、とてもシンプルです。
hostname ASR1001 ! vrf definition SERVICES ! address-family ipv4 exit-address-family ! vrf definition USER-A ! address-family ipv4 route-replicate from vrf SERVICES unicast all exit-address-family ! vrf definition USER-B ! address-family ipv4 route-replicate from vrf SERVICES unicast all exit-address-family ! vrf definition USER-C ! address-family ipv4 route-replicate from vrf SERVICES unicast all exit-address-family ! interface GigabitEthernet0/0/0 no ip address negotiation auto ! interface GigabitEthernet0/0/0.10 encapsulation dot1Q 10 vrf forwarding USER-A ip address 10.1.1.1 255.255.255.0 ip nat inside ! interface GigabitEthernet0/0/0.20 encapsulation dot1Q 20 vrf forwarding USER-B ip address 10.1.1.1 255.255.255.0 ip nat inside ! interface GigabitEthernet0/0/0.30 encapsulation dot1Q 30 vrf forwarding USER-C ip address 10.1.1.1 255.255.255.0 ip nat inside ! interface GigabitEthernet0/0/1 no ip address negotiation auto ! interface GigabitEthernet0/0/1.100 encapsulation dot1Q 100 vrf forwarding SERVICES ip address 172.16.1.1 255.255.255.0 ip nat outside ! ip nat inside source static 192.168.1.100 1.1.1.100 vrf USER-A ip nat inside source static 192.168.1.100 1.1.2.100 vrf USER-B ip nat inside source static 192.168.1.100 1.1.3.100 vrf USER-C ! ip route vrf USER-A 192.168.1.0 255.255.255.0 10.1.1.2 ip route vrf USER-B 192.168.1.0 255.255.255.0 10.1.1.2 ip route vrf USER-C 192.168.1.0 255.255.255.0 10.1.1.2 <...snip...>
上記例では、SERVICE RIB を全てコピーしていますが、Route-MAP を併用し、任意のネットワークのみコピーする事も可能です。例えば、下記は tag:5000 を付与した静的ルートのみコピーする例になります。
ASR1001#conf t Enter configuration commands, one per line. End with CNTL/Z. ASR1001(config)#vrf definition SERVICES ASR1001(config-vrf)# address-family ipv4 ASR1001(config-vrf-af)#route-replicate from vrf USER-A unicast static route-map USER-A ASR1001(config-vrf-af)#exit ASR1001(config-vrf)#exit ASR1001(config)#route-map USER-A ASR1001(config-route-map)#match tag 5000 ASR1001(config-route-map)#exit ASR1001(config)#ip route vrf USER-A 0.0.0.0 0.0.0.0 10.1.1.2 tag 5000
ルーティングテーブル確認方法
ルーティングテーブルの確認は、従来の show ip route vrf "VRF NAME" コマンド及び、routing-context モードから行う事が可能です。下記は、routing-context モードを使用した際の例になります。
左側に"+"が付いているネットワークが、Route Replication により、leak された情報になります。
VRF USER-A のルーティング情報
ASR1001#routing-context vrf USER-A ASR1001%USER-A#sh ip route Routing Table: USER-A 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 + - replicated route, % - next hop override Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.1.1.0/24 is directly connected, GigabitEthernet0/0/0.10 L 10.1.1.1/32 is directly connected, GigabitEthernet0/0/0.10 172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks C 172.16.1.0/24 is directly connected, GigabitEthernet0/0/1.10 L 172.16.1.1/32 is directly connected, GigabitEthernet0/0/1.10 C + 172.16.1.0/24 is directly connected (SERVICES), GigabitEthernet0/0/1.100 L 172.16.1.1/32 is directly connected, GigabitEthernet0/0/1.100 S 192.168.1.0/24 [1/0] via 10.1.1.2
VRF USER-B のルーティング情報
ASR1001%USER-A#routing-context vrf USER-B ASR1001%USER-B#sh ip route Routing Table: USER-B 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 + - replicated route, % - next hop override Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.1.1.0/24 is directly connected, GigabitEthernet0/0/0.20 L 10.1.1.1/32 is directly connected, GigabitEthernet0/0/0.20 172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks C 172.16.1.0/24 is directly connected, GigabitEthernet0/0/1.20 L 172.16.1.1/32 is directly connected, GigabitEthernet0/0/1.20 C + 172.16.1.0/24 is directly connected (SERVICES), GigabitEthernet0/0/1.100 L 172.16.1.1/32 is directly connected, GigabitEthernet0/0/1.100 S 192.168.1.0/24 [1/0] via 10.1.1.2
VRF USER-C のルーティング情報
ASR1001%USER-B#routing-context vrf USER-C ASR1001%USER-C#sh ip route Routing Table: USER-C 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 + - replicated route, % - next hop override Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.1.1.0/24 is directly connected, GigabitEthernet0/0/0.30 L 10.1.1.1/32 is directly connected, GigabitEthernet0/0/0.30 172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks C 172.16.1.0/24 is directly connected, GigabitEthernet0/0/1.30 L 172.16.1.1/32 is directly connected, GigabitEthernet0/0/1.30 C + 172.16.1.0/24 is directly connected (SERVICES), GigabitEthernet0/0/1.100 L 172.16.1.1/32 is directly connected, GigabitEthernet0/0/1.100 S 192.168.2.0/24 [1/0] via 10.1.1.2
VRF SERVICES のルーティング情報
ASR1001%USER-C#routing-context vrf SERVICES ASR1001%SERVICES#sh ip route Routing Table: SERVICES 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 + - replicated route, % - next hop override Gateway of last resort is not set 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks C 172.16.1.0/24 is directly connected, GigabitEthernet0/0/1.100 L 172.16.1.1/32 is directly connected, GigabitEthernet0/0/1.100
なお、Native なルーティングテーブルに戻るには、"routing-context vrf global" を発行します。
以上