Начиная с версии ПО 3.6.0 на маршрутизаторах ME реализована поддержка функционала OSPF multi-area Adjacency.
Функционал позвоняет организовывать на линке между двумя маршрутизаторами связность для нескольких OSPF area.
На схеме ниже показан один из примеров, когда это может понадобиться на сети.
Маршрутизаторы R1, R2 и R3 принадлежат area 0 и соединены высокоскоростными линками. Маршрутизаторы также являются ABR для area 1 и 2.
При традиционной конфигурации OSPF линки R1-R2 и R2-R3 будут принадлежать Area 0. При этом трафик сетей, включенных в маршрутизаторы R21 и R26 будет проходить по маршруту R21-R22-R23-R24-R25-R26,
так как маршруты, полученные от ABR являются inter area и проигрывают маршрутам intra area вне зависимости от метрики. Аналогичная ситуация с маршрутизаторами R11 и R14.
Очевидно, что в данном случае такая маршрутизация не оптимальна, и часть трафика стоит маршрутизировать через линки Area 0.
Схема стенда
Ниже приведен пример конфигурации OSPF маршрутизаторов R1-R3 и состояние соседств.
0/ME5200:R1# sh run router ospfv2 Tue Aug 29 17:58:23 2023 ! Configuration version 3.6.0.198R router ospfv2 1 area 0.0.0.0 interface tengigabitethernet 0/0/32 network point-to-point exit exit area 0.0.0.1 interface tengigabitethernet 0/0/31 network point-to-point exit exit area 0.0.0.2 interface tengigabitethernet 0/0/5.952 network point-to-point exit exit router-id 10.0.0.1 exit 0/ME5200:R1# sh ospfv2 neighbors Wed Aug 30 11:13:04 2023 Routing Process: 1, ID 10.0.0.1 Router is an area border router Neighbor ID Area ID Pri State BFD Dead Time Last state change Address Interface ---------------- ---------------- ---- ------------------- ------------- ---------- ------------------ ---------------- ---------- 10.0.0.11 0.0.0.1 1 full not-required 00:00:37 19h36m05s 10.0.0.74 te0/0/31 10.0.0.2 0.0.0.0 1 full not-required 00:00:37 23h45m10s 10.0.0.58 te0/0/32 10.0.0.21 0.0.0.2 1 full not-required 00:00:37 23h53m42s 10.0.0.37 te0/0/5.952 ================================================ 0/ME5100revX:R2# sh run router ospfv2 Tue Aug 29 10:59:31 2023 ! Configuration version 3.6.0.198R router ospfv2 1 area 0.0.0.0 interface tengigabitethernet 0/0/2 network point-to-point exit interface tengigabitethernet 0/0/13 network point-to-point exit exit area 0.0.0.2 interface tengigabitethernet 0/0/5.951 network point-to-point exit exit router-id 10.0.0.2 exit 0/ME5100revX:R2# sh ospfv2 nei Wed Aug 30 04:14:39 2023 Routing Process: 1, ID 10.0.0.2 Router is an area border router Neighbor ID Area ID Pri State BFD Dead Time Last state change Address Interface ---------------- ---------------- ---- ------------------- ------------- ---------- ------------------ ---------------- ---------- 10.0.0.1 0.0.0.0 1 full not-required 00:00:34 23h47m16s 10.0.0.57 te0/0/13 10.0.0.3 0.0.0.0 1 full not-required 00:00:36 23h38m31s 10.0.0.62 te0/0/2 10.0.0.26 0.0.0.2 1 full not-required 00:00:37 05h03m30s 10.0.0.34 te0/0/5.951 =============================================== 0/ME5100:R3# sh run router ospfv2 Tue Aug 29 11:04:14 2023 ! Configuration version 3.6.0.198R router ospfv2 1 area 0.0.0.0 exit interface tengigabitethernet 0/0/4 network point-to-point exit exit area 0.0.0.1 interface tengigabitethernet 0/0/15 network point-to-point exit exit router-id 10.0.0.3 exit 0/ME5100:R3# sh ospfv2 nei Wed Aug 30 04:17:31 2023 Routing Process: 1, ID 10.0.0.3 Router is an area border router Neighbor ID Area ID Pri State BFD Dead Time Last state change Address Interface ---------------- ---------------- ---- ------------------- ------------- ---------- ------------------ ---------------- ---------- 10.0.0.14 0.0.0.1 1 full not-required 00:00:39 22h42m20s 10.0.0.66 te0/0/15 10.0.0.2 0.0.0.0 1 full not-required 00:00:36 23h39m04s 10.0.0.61 te0/0/4
Нише показаны маршруты на ABR R1 и на маршрутизаторах area1 и area2. В area2 используются маршрутизаторы Cisco CSR-1000v.
К маршрутизаторам R11, R14, R21 и R26 подключены соответственно сети 192.168.11.0/24, 192.168.14.0/24, 192.168.21.0/24 и 192.168.26.0/24. Метрики Intra Area линков area 1 и 2 увеличены.
Видно, что сети
0/ME5200:R1# sh route Tue Aug 29 18:04:08 2023 Codes: C - connected, S - static, O - OSPF, B - BGP, L - local IA - OSPF inter area, EA - OSPF intra 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, L1 - IS-IS level-1, L2 - IS-IS level-2, LE1 - IS-IS level1 external, LE2 - IS-IS level2 external BI - BGP internal, BE - BGP external, BV - BGP vpn, BL - BGP labeled, R - RIP O EA 10.0.0.32/30 via 10.0.0.37 [30/102], 02h15m43s, te0/0/5.952 C 10.0.0.36/30 is directly connected, 04d00h20m, te0/0/5.952 L 10.0.0.38/32 is directly connected, 04d00h20m, te0/0/5.952 O EA 10.0.0.52/30 via 10.0.0.37 [30/101], 02h15m43s, te0/0/5.952 C 10.0.0.56/30 is directly connected, 06h53m59s, te0/0/32 L 10.0.0.57/32 is directly connected, 06h53m59s, te0/0/32 O EA 10.0.0.60/30 via 10.0.0.58 [30/2], 06h36m05s, te0/0/32 O EA 10.0.0.64/30 via 10.0.0.74 [30/102], 02h27m00s, te0/0/31 O EA 10.0.0.68/30 via 10.0.0.74 [30/101], 02h27m00s, te0/0/31 C 10.0.0.72/30 is directly connected, 02h27m15s, te0/0/31 L 10.0.0.73/32 is directly connected, 02h27m15s, te0/0/31 O EA 192.168.11.0/24 via 10.0.0.74 [30/1], 02h21m09s, te0/0/31 O EA 192.168.14.0/24 via 10.0.0.74 [30/102], 02h20m39s, te0/0/31 O EA 192.168.21.0/24 via 10.0.0.37 [30/2], 02h14m29s, te0/0/5.952 O EA 192.168.26.0/24 via 10.0.0.37 [30/102], 02h13m07s, te0/0/5.952 ============================================================== 0/FMC0:R11# sh route Tue Aug 29 11:08:33 2023 Codes: C - connected, S - static, O - OSPF, B - BGP, L - local IA - OSPF inter area, EA - OSPF intra 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, L1 - IS-IS level-1, L2 - IS-IS level-2, LE1 - IS-IS level1 external, LE2 - IS-IS level2 external BI - BGP internal, BE - BGP external, BV - BGP vpn, BL - BGP labeled, R - RIP O IA 10.0.0.32/30 via 10.0.0.73 [30/103], 02h20m02s, te0/0/6 O IA 10.0.0.36/30 via 10.0.0.73 [30/2], 02h31m24s, te0/0/6 O IA 10.0.0.52/30 via 10.0.0.73 [30/102], 02h20m02s, te0/0/6 O IA 10.0.0.56/30 via 10.0.0.73 [30/2], 02h31m24s, te0/0/6 O IA 10.0.0.60/30 via 10.0.0.73 [30/3], 02h31m24s, te0/0/6 O EA 10.0.0.64/30 via 10.0.0.69 [30/101], 02h33m51s, te0/0/5 C 10.0.0.68/30 is directly connected, 02h35m43s, te0/0/5 L 10.0.0.70/32 is directly connected, 02h35m43s, te0/0/5 C 10.0.0.72/30 is directly connected, 02h35m43s, te0/0/6 L 10.0.0.74/32 is directly connected, 02h35m43s, te0/0/6 C 192.168.11.0/24 is directly connected, 00h18m14s, te0/0/5.15 L 192.168.11.1/32 is directly connected, 00h18m14s, te0/0/5.15 O EA 192.168.14.0/24 via 10.0.0.69 [30/101], 02h25m03s, te0/0/5 O IA 192.168.21.0/24 via 10.0.0.73 [30/3], 02h18m48s, te0/0/6 O IA 192.168.26.0/24 via 10.0.0.73 [30/103], 02h17m26s, te0/0/6 ============================================================== R26#sh 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 10.0.0.0/8 is variably subnetted, 18 subnets, 3 masks C 10.0.0.32/30 is directly connected, GigabitEthernet1.951 L 10.0.0.34/32 is directly connected, GigabitEthernet1.951 O 10.0.0.36/30 [110/101] via 10.0.0.53, 17:59:45, GigabitEthernet1.950 C 10.0.0.52/30 is directly connected, GigabitEthernet1.950 L 10.0.0.54/32 is directly connected, GigabitEthernet1.950 O IA 10.0.0.56/30 [110/2] via 10.0.0.33, 03:38:19, GigabitEthernet1.951 O IA 10.0.0.60/30 [110/2] via 10.0.0.33, 03:38:19, GigabitEthernet1.951 O IA 10.0.0.64/30 [110/3] via 10.0.0.33, 03:38:19, GigabitEthernet1.951 O IA 10.0.0.68/30 [110/103] via 10.0.0.33, 03:38:19, GigabitEthernet1.951 O IA 10.0.0.72/30 [110/3] via 10.0.0.33, 03:38:19, GigabitEthernet1.951 192.168.11.0/32 is subnetted, 1 subnets O IA 192.168.11.1 [110/3] via 10.0.0.33, 03:38:19, GigabitEthernet1.951 192.168.14.0/32 is subnetted, 1 subnets O IA 192.168.14.1 [110/4] via 10.0.0.33, 03:38:19, GigabitEthernet1.951 192.168.21.0/32 is subnetted, 1 subnets O 192.168.21.1 [110/101] via 10.0.0.53, 17:59:45, GigabitEthernet1.950 192.168.26.0/24 is variably subnetted, 2 subnets, 2 masks C 192.168.26.0/24 is directly connected, Loopback15 L 192.168.26.1/32 is directly connected, Loopback15
Настраиваем на маршрутизаторах R1-R3 дополнительные связности на линках, принадлежащих area 0. Ниже конфигурация и состояние соседств.
0/ME5200:R1# sh run router ospfv2 Wed Aug 30 16:05:32 2023 ! Configuration version 3.6.0.198R router ospfv2 1 area 0.0.0.0 interface tengigabitethernet 0/0/32 network point-to-point exit exit area 0.0.0.1 interface tengigabitethernet 0/0/31 network point-to-point exit multi-area-interface tengigabitethernet 0/0/32 exit exit area 0.0.0.2 interface tengigabitethernet 0/0/5.952 network point-to-point exit multi-area-interface tengigabitethernet 0/0/32 exit exit router-id 10.0.0.1 exit 0/ME5200:R1# sh ospfv2 neighbors Wed Aug 30 16:17:39 2023 Routing Process: 1, ID 10.0.0.1 Router is an area border router Neighbor ID Area ID Pri State BFD Dead Time Last state change Address Interface ---------------- ---------------- ---- ------------------- ------------- ---------- ------------------ ---------------- ---------- 10.0.0.11 0.0.0.1 1 full not-required 00:00:32 00h24m37s 10.0.0.74 te0/0/31 10.0.0.2 0.0.0.0 1 full not-required 00:00:32 00h24m37s 10.0.0.58 te0/0/32 10.0.0.21 0.0.0.2 1 full not-required 00:00:31 00h24m47s 10.0.0.37 te0/0/5.952 10.0.0.2 0.0.0.1 -- full -- 00:00:32 00h15m06s 10.0.0.58 MA te0/0/32 10.0.0.2 0.0.0.2 -- full -- 00:00:32 00h15m06s 10.0.0.58 MA te0/0/32 =================================================================== 0/ME5100revX:R2# sh run router ospfv2 Wed Aug 30 16:11:22 2023 ! Configuration version 3.6.0.198R router ospfv2 1 area 0.0.0.0 interface tengigabitethernet 0/0/2 network point-to-point exit interface tengigabitethernet 0/0/13 network point-to-point exit exit area 0.0.0.1 multi-area-interface tengigabitethernet 0/0/2 exit multi-area-interface tengigabitethernet 0/0/13 exit exit area 0.0.0.2 interface tengigabitethernet 0/0/5.951 network point-to-point exit multi-area-interface tengigabitethernet 0/0/2 exit multi-area-interface tengigabitethernet 0/0/13 exit exit router-id 10.0.0.2 exit 0/ME5100revX:R2# sh ospfv2 nei Wed Aug 30 16:17:25 2023 Routing Process: 1, ID 10.0.0.2 Router is an area border router Neighbor ID Area ID Pri State BFD Dead Time Last state change Address Interface ---------------- ---------------- ---- ------------------- ------------- ---------- ------------------ ---------------- ---------- 10.0.0.1 0.0.0.0 1 full not-required 00:00:37 00h25m02s 10.0.0.57 te0/0/13 10.0.0.3 0.0.0.0 1 full not-required 00:00:39 00h26m50s 10.0.0.62 te0/0/2 10.0.0.26 0.0.0.2 1 full not-required 00:00:31 00h26m59s 10.0.0.34 te0/0/5.951 10.0.0.1 0.0.0.1 -- full -- 00:00:38 00h15m31s 10.0.0.57 MA te0/0/13 10.0.0.1 0.0.0.2 -- full -- 00:00:38 00h15m31s 10.0.0.57 MA te0/0/13 10.0.0.3 0.0.0.1 -- full -- 00:00:39 00h13m23s 10.0.0.62 MA te0/0/2 10.0.0.3 0.0.0.2 -- full -- 00:00:39 00h13m23s 10.0.0.62 MA te0/0/2 ============================================================= 0/ME5100:R3# sh run router ospfv2 Wed Aug 30 09:16:01 2023 ! Configuration version 3.6.0.198R router ospfv2 1 area 0.0.0.0 interface tengigabitethernet 0/0/4 network point-to-point exit exit area 0.0.0.1 interface tengigabitethernet 0/0/15 network point-to-point exit multi-area-interface tengigabitethernet 0/0/4 exit exit area 0.0.0.2 multi-area-interface tengigabitethernet 0/0/4 exit exit router-id 10.0.0.3 exit 0/ME5100:R3# sh ospfv2 neighbors Wed Aug 30 09:21:12 2023 Routing Process: 1, ID 10.0.0.3 Router is an area border router Neighbor ID Area ID Pri State BFD Dead Time Last state change Address Interface ---------------- ---------------- ---- ------------------- ------------- ---------- ------------------ ---------------- ---------- 10.0.0.14 0.0.0.1 1 full not-required 00:00:35 00h28m14s 10.0.0.66 te0/0/15 10.0.0.2 0.0.0.0 1 full not-required 00:00:37 00h27m43s 10.0.0.61 te0/0/4 10.0.0.2 0.0.0.1 -- full -- 00:00:34 00h14m15s 10.0.0.61 MA te0/0/4 10.0.0.2 0.0.0.2 -- full -- 00:00:34 00h14m15s 10.0.0.61 MA te0/0/4
Теперь связность между сетями маршрутизаторов одной area по через линки с multi-area соседством:
0/ME5200:R1# sh route Wed Aug 30 17:18:08 2023 Codes: C - connected, S - static, O - OSPF, B - BGP, L - local IA - OSPF inter area, EA - OSPF intra 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, L1 - IS-IS level-1, L2 - IS-IS level-2, LE1 - IS-IS level1 external, LE2 - IS-IS level2 external BI - BGP internal, BE - BGP external, BV - BGP vpn, BL - BGP labeled, R - RIP O EA 10.0.0.32/30 via 10.0.0.58 [30/2], 01h15m30s, te0/0/32 C 10.0.0.36/30 is directly connected, 01h25m16s, te0/0/5.952 L 10.0.0.38/32 is directly connected, 01h25m16s, te0/0/5.952 O EA 10.0.0.52/30 via 10.0.0.37 [30/101], 01h25m06s, te0/0/5.952 C 10.0.0.56/30 is directly connected, 01h25m16s, te0/0/32 L 10.0.0.57/32 is directly connected, 01h25m16s, te0/0/32 O EA 10.0.0.60/30 via 10.0.0.58 [30/2], 01h24m56s, te0/0/32 O EA 10.0.0.64/30 via 10.0.0.58 [30/3], 01h13m21s, te0/0/32 O EA 10.0.0.68/30 via 10.0.0.74 [30/101], 00h27m14s, te0/0/31 C 10.0.0.72/30 is directly connected, 01h25m16s, te0/0/31 L 10.0.0.73/32 is directly connected, 01h25m16s, te0/0/31 O EA 192.168.11.0/24 via 10.0.0.74 [30/1], 00h22m24s, te0/0/31 O EA 192.168.14.0/24 via 10.0.0.58 [30/3], 00h17m21s, te0/0/32 O EA 192.168.21.0/24 via 10.0.0.37 [30/2], 00h15m42s, te0/0/5.952 O EA 192.168.26.0/24 via 10.0.0.58 [30/3], 00h16m24s, te0/0/32 ================================================================ 0/FMC0:R11# 0/FMC0:R11# sh route Wed Aug 30 09:21:47 2023 Codes: C - connected, S - static, O - OSPF, B - BGP, L - local IA - OSPF inter area, EA - OSPF intra 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, L1 - IS-IS level-1, L2 - IS-IS level-2, LE1 - IS-IS level1 external, LE2 - IS-IS level2 external BI - BGP internal, BE - BGP external, BV - BGP vpn, BL - BGP labeled, R - RIP O IA 10.0.0.32/30 via 10.0.0.73 [30/3], 00h00m19s, te0/0/6 O IA 10.0.0.36/30 via 10.0.0.73 [30/2], 00h00m19s, te0/0/6 O IA 10.0.0.52/30 via 10.0.0.73 [30/102], 00h00m19s, te0/0/6 O IA 10.0.0.56/30 via 10.0.0.73 [30/2], 00h00m19s, te0/0/6 O IA 10.0.0.60/30 via 10.0.0.73 [30/3], 00h00m19s, te0/0/6 O EA 10.0.0.64/30 via 10.0.0.73 [30/4], 00h00m34s, te0/0/6 C 10.0.0.68/30 is directly connected, 01d00h48m, te0/0/5 L 10.0.0.70/32 is directly connected, 01d00h48m, te0/0/5 C 10.0.0.72/30 is directly connected, 00h28m56s, te0/0/6 L 10.0.0.74/32 is directly connected, 00h28m56s, te0/0/6 C 192.168.11.0/24 is directly connected, 00h19m26s, te0/0/5.15 L 192.168.11.1/32 is directly connected, 00h19m26s, te0/0/5.15 O EA 192.168.14.0/24 via 10.0.0.73 [30/4], 00h14m09s, te0/0/6 O IA 192.168.21.0/24 via 10.0.0.73 [30/3], 00h12m25s, te0/0/6 O IA 192.168.26.0/24 via 10.0.0.73 [30/4], 00h13m07s, te0/0/6 ======================================================== R26#sh 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 10.0.0.0/8 is variably subnetted, 18 subnets, 3 masks C 10.0.0.32/30 is directly connected, GigabitEthernet1.951 L 10.0.0.34/32 is directly connected, GigabitEthernet1.951 O 10.0.0.36/30 [110/3] via 10.0.0.33, 01:17:59, GigabitEthernet1.951 C 10.0.0.52/30 is directly connected, GigabitEthernet1.950 L 10.0.0.54/32 is directly connected, GigabitEthernet1.950 O IA 10.0.0.56/30 [110/2] via 10.0.0.33, 01:27:41, GigabitEthernet1.951 O IA 10.0.0.60/30 [110/2] via 10.0.0.33, 01:29:18, GigabitEthernet1.951 O IA 10.0.0.64/30 [110/3] via 10.0.0.33, 01:15:41, GigabitEthernet1.951 O IA 10.0.0.68/30 [110/103] via 10.0.0.33, 01:15:41, GigabitEthernet1.951 O IA 10.0.0.72/30 [110/3] via 10.0.0.33, 01:27:26, GigabitEthernet1.951 O IA 192.168.11.0/24 [110/3] via 10.0.0.33, 00:24:54, GigabitEthernet1.951 O IA 192.168.14.0/24 [110/3] via 10.0.0.33, 00:19:50, GigabitEthernet1.951 O 192.168.21.0/24 [110/4] via 10.0.0.33, 00:18:07, GigabitEthernet1.951 192.168.26.0/24 is variably subnetted, 2 subnets, 2 masks C 192.168.26.0/24 is directly connected, GigabitEthernet1.959 L 192.168.26.1/32 is directly connected, GigabitEthernet1.959
Особенностью маршрутизаторов ME является то, что multi-area связность может быть настроена не только на p2p интерфейсе.
Для этого при конфигурации нужно указать адрес соседа с которым эта связность будет настраиваться.
0/ME5200:R1# sh run router ospfv2 Wed Aug 30 16:05:32 2023 ! Configuration version 3.6.0.198R router ospfv2 1 area 0.0.0.0 interface tengigabitethernet 0/0/32 exit exit area 0.0.0.1 interface tengigabitethernet 0/0/31 network point-to-point exit multi-area-interface tengigabitethernet 0/0/32 neighbor 10.0.0.58 exit exit area 0.0.0.2 interface tengigabitethernet 0/0/5.952 network point-to-point exit multi-area-interface tengigabitethernet 0/0/32 neighbor 10.0.0.58 exit exit router-id 10.0.0.1 exit ==================================================== 0/ME5100revX:R2# sh run router ospfv2 Wed Aug 30 16:11:22 2023 ! Configuration version 3.6.0.198R router ospfv2 1 area 0.0.0.0 interface tengigabitethernet 0/0/2 network point-to-point exit interface tengigabitethernet 0/0/13 exit exit area 0.0.0.1 multi-area-interface tengigabitethernet 0/0/2 exit multi-area-interface tengigabitethernet 0/0/13 neighbor 10.0.0.57 exit exit area 0.0.0.2 interface tengigabitethernet 0/0/5.951 network point-to-point exit multi-area-interface tengigabitethernet 0/0/2 exit multi-area-interface tengigabitethernet 0/0/13 neighbor 10.0.0.57 exit exit router-id 10.0.0.2 exit