////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////// Summarization of routes in OSPF - CASE 1 Route Summarization is the consolidation of routes into a single advertisement Reference Diagram: diag_sum1.ps ////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////// ===================================== Configuration for route summarization ===================================== Dexter : ASBR in Area 0 (Backbone area), ABR (Area 0 and Area 2) Radia : internal router for Area 1 Tony : router with an interface each in Area 1 and Area 2 Mrhorse : Internal router for Area 2 Yakov : Internal router for Area 1 Big-baby: ASBR in Area 0 (Backbone area), ABR (Area 0 and Area 1) After running OSPF in all the 3 areas, we did route summarization using the following command: >area [area-id] range [address] [mask] area-id - the id of the area containing networks to be summarized address - IP address mask - IP mask 1. This command is used only with Area Border Routers of the areas for which routes need to be summarized 2. As a result of route summarization, the ABRs will advertize only a single summary route to other areas. 3. Route summarization command was used in ABRs Dexter and Big-Baby The configuration for the different routers is shown below. DEXTER ====== dexter#config t Enter configuration commands, one per line. End with CNTL/Z. dexter(config)#router ospf 100 dexter(config-router)#network 131.252.215.4 0.0.0.0 area 0 dexter(config-router)#network 131.252.215.33 0.0.0.0 area 2 dexter(config-router)#default-information originate metric-type 1 dexter(config-router)#area 2 range 131.252.215.32 255.255.255.224 dexter(config-router)#^Z dexter# RADIA ===== radia#config t Enter configuration commands, one per line. End with CNTL/Z. radia(config)#router ospf 100 radia(config-router)#network 131.252.215.34 0.0.0.0 area 2 radia(config-router)#network 131.252.215.49 0.0.0.0 area 2 radia(config-router)#^Z radia# MRHORSE ======= mrhorse#config t Enter configuration commands, one per line. End with CNTL/Z. mrhorse(config)#router ospf 100 mrhorse(config-router)#network 131.252.215.35 0.0.0.0 area 2 mrhorse(config-router)#^Z mrhorse# TONY ==== tony#config t Enter configuration commands, one per line. End with CNTL/Z. tony(config)#router ospf 100 tony(config-router)#network 131.252.215.50 0.0.0.0 area 2 tony(config-router)#network 131.252.215.65 0.0.0.0 area 1 tony(config-router)#^Z tony#sh YAKOV ===== yakov#config t Enter configuration commands, one per line. End with CNTL/Z. yakov(config)#router ospf 100 yakov(config-router)#network 131.252.215.66 0.0.0.0 area 1 yakov(config-router)#network 131.252.215.81 0.0.0.0 area 1 yakov(config-router)#^Z yakov(config-router)# yakov# BIG-BABY ======== big-baby#config t Enter configuration commands, one per line. End with CNTL/Z. big-baby(config)#router ospf 100 big-baby(config-router)#network 131.252.215.10 0.0.0.0 area 0 big-baby(config-router)#network 131.252.215.82 0.0.0.0 area 1 big-baby(config-router)#area 1 range 131.252.215.64 255.255.255.224 big-baby(config-router)#^Z big-baby# ////////////////////////////////////////////////////////////////////////// ============================================= EFFECT OF THE ROUTE SUMMARIZATION ON IP ROUTE ============================================= The results of the "show ip route" command are shown below for every router. DEXTER ------ - In Area 1, we can see that there is now an area range of 131.252.215.32/27 BEFORE SUMMARIZATION>>>>There are 6 routes in total dexter#sh ip route Codes: C - connected, S - static, I - IGRP, 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, E - EGP i - IS-IS, 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 Gateway of last resort is 131.252.215.1 to network 0.0.0.0 131.252.0.0/16 is variably subnetted, 5 subnets, 2 masks C 131.252.215.32/28 is directly connected, FastEthernet0/1 O 131.252.215.48/28 [110/2] via 131.252.215.34, 00:03:45, FastEthernet0/1 C 131.252.215.0/27 is directly connected, FastEthernet0/0 O IA 131.252.215.64/28 [110/12] via 131.252.215.10, 00:03:45, FastEthernet0/0 O IA 131.252.215.80/28 [110/11] via 131.252.215.10, 00:03:45, FastEthernet0/0 S* 0.0.0.0/0 [1/0] via 131.252.215.1 AFTER SUMMARIZATION>>>> - There are only 5 routes. The .64/28 (metric 12) and .80/28 (metric 11) networks have been summarized into a .64/27 network and the new summarized route has the lower cost metric of the two routes. dexter#sh ip route Codes: C - connected, S - static, I - IGRP, 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, E - EGP i - IS-IS, 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 Gateway of last resort is 131.252.215.1 to network 0.0.0.0 131.252.0.0/16 is variably subnetted, 4 subnets, 2 masks C 131.252.215.32/28 is directly connected, FastEthernet0/1 O 131.252.215.48/28 [110/2] via 131.252.215.34, 00:11:27, FastEthernet0/1 C 131.252.215.0/27 is directly connected, FastEthernet0/0 O IA 131.252.215.64/27 [110/11] via 131.252.215.10, 00:10:20, FastEthernet0/0 S* 0.0.0.0/0 [1/0] via 131.252.215.1 BIG-BABY -------- BEFORE SUMMARIZATION>>>>There are 6 routes in total big-baby#sh ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default Gateway of last resort is 131.252.215.4 to network 0.0.0.0 131.252.0.0 is variably subnetted, 5 subnets, 2 masks O IA 131.252.215.32 255.255.255.240 [110/11] via 131.252.215.4, 00:09:48, Ethernet0/1 O IA 131.252.215.48 255.255.255.240 [110/12] via 131.252.215.4, 00:09:48, Ethernet0/1 C 131.252.215.0 255.255.255.224 is directly connected, Ethernet0/1 O 131.252.215.64 255.255.255.240 [110/11] via 131.252.215.81, 01:28:10, Ethernet0/0 C 131.252.215.80 255.255.255.240 is directly connected, Ethernet0/0 O*E1 0.0.0.0 0.0.0.0 [110/11] via 131.252.215.4, 00:09:48, Ethernet0/1 AFTER SUMMARIZATION>>>> - There are only 5 routes. The .32 (metric 11) and .48 (metric 12) networks have been\ summarized into a .32/27 network with the higher cost metric of the two routes. big-baby#sh ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default Gateway of last resort is 131.252.215.4 to network 0.0.0.0 131.252.0.0 is variably subnetted, 4 subnets, 2 masks O IA 131.252.215.32 255.255.255.224 [110/12] via 131.252.215.4, 00:00:40, Ethernet0/1 C 131.252.215.0 255.255.255.224 is directly connected, Ethernet0/1 O 131.252.215.64 255.255.255.240 [110/11] via 131.252.215.81, 00:00:41, Ethernet0/0 C 131.252.215.80 255.255.255.240 is directly connected, Ethernet0/0 O*E1 0.0.0.0 0.0.0.0 [110/11] via 131.252.215.4, 00:00:41, Ethernet0/1 RADIA ---- AFTER SUMMARIZATION>>>> -Only 5 routes are shown (instead of 6). The .64 network has been made a /27 network (instead of /28, metric 13 and the route to .80/28 (metric 12) is missing. The new summarized route has the lower metric of the two routes. radia#sh i[   p route Codes: C - connected, S - static, I - IGRP, 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, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR T - traffic engineered route Gateway of last resort is 131.252.215.33 to network 0.0.0.0 131.252.0.0/16 is variably subnetted, 4 subnets, 2 masks C 131.252.215.32/28 is directly connected, FastEthernet0/0 C 131.252.215.48/28 is directly connected, FastEthernet0/1 O IA 131.252.215.0/27 [110/2] via 131.252.215.33, FastEthernet0/0 O IA 131.252.215.64/27 [110/12] via 131.252.215.33, FastEthernet0/0 O*E1 0.0.0.0/0 [110/2] via 131.252.215.33, FastEthernet0/0 TONY ---- AFTER SUMMARIZATION>>>> - There are 8 routes here. Since Tony has no summarization information, it gets duplicate routes to the same network. For example, from yakov it gets the route .32/27 and from Radia it gets route .32/28. The same thing happens for the .64 network. - routes to .48/28 and .80/28 networks are present too. tony#sh ip route Codes: C - connected, S - static, I - IGRP, 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, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR T - traffic engineered route Gateway of last resort is 131.252.215.49 to network 0.0.0.0 131.252.0.0/16 is variably subnetted, 7 subnets, 2 masks O IA 131.252.215.32/27 [110/14] via 131.252.215.66, FastEthernet0/1 O 131.252.215.32/28 [110/2] via 131.252.215.49, FastEthernet0/0 C 131.252.215.48/28 is directly connected, FastEthernet0/0 O IA 131.252.215.0/27 [110/3] via 131.252.215.49, FastEthernet0/0 O IA 131.252.215.64/27 [110/13] via 131.252.215.49, FastEthernet0/0 C 131.252.215.64/28 is directly connected, FastEthernet0/1 O 131.252.215.80/28 [110/2] via 131.252.215.66, FastEthernet0/1 O*E1 0.0.0.0/0 [110/3] via 131.252.215.49, FastEthernet0/0 MRHORSE ------- AFTER SUMMARIZATION>>>> -There are 5 routes shown(instead of 6). The .64 network has been made a /27 network (instead of /28, metric 22) and the route to .80/28 (metric 21) is missing. The new summarized route has the lower metric of the two routes. mrhorse#sh ip route Codes: C - connected, S - static, I - IGRP, 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, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is 131.252.215.33 to network 0.0.0.0 131.252.0.0/16 is variably subnetted, 4 subnets, 2 masks C 131.252.215.32/28 is directly connected, Ethernet0 O 131.252.215.48/28 [110/11] via 131.252.215.34, 00:24:04, Ethernet0 O IA 131.252.215.0/27 [110/11] via 131.252.215.33, 00:24:04, Ethernet0 O IA 131.252.215.64/27 [110/21] via 131.252.215.33, 00:08:08, Ethernet0 O*E1 0.0.0.0/0 [110/11] via 131.252.215.33, 00:24:04, Ethernet0 YAKOV ----- AFTER SUMMARIZATION>>>> -Only 5 routes are shown (instead of 6). The .32 network has been made a /27 network (instead of /28, metric 12) and the route to .48/28 (metric 13) is missing. The new summarized route has the higher metric of the two routes. yakov#sh ip route Codes: C - connected, S - static, I - IGRP, 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, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR T - traffic engineered route Gateway of last resort is 131.252.215.82 to network 0.0.0.0 131.252.0.0/16 is variably subnetted, 4 subnets, 2 masks O IA 131.252.215.32/27 [110/13] via 131.252.215.82, FastEthernet0/1 O IA 131.252.215.0/27 [110/11] via 131.252.215.82, FastEthernet0/1 C 131.252.215.64/28 is directly connected, FastEthernet0/0 C 131.252.215.80/28 is directly connected, FastEthernet0/1 O*E1 0.0.0.0/0 [110/12] via 131.252.215.82, FastEthernet0/1 ============================================= EFFECT OF ROUTE SUMMARIZATION ON OSPF SUMMARY ============================================= The results of the "show ip ospf" command are shown below for every router. DEXTER ------ -After summarization, in Area 2, we can see that Area Ranges are being reported for Dexter by the following two lines..... Area ranges are 131.252.215.32/27 Active(2) Advertise dexter#sh ip ospf Routing Process "ospf 100" with ID 131.252.215.33 Supports only single TOS(TOS0) routes Supports opaque LSA It is an area border and autonomous system boundary router Redistributing External Routes from, SPF schedule delay 5 secs, Hold time between two SPFs 10 secs Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs Number of external LSA 1. Checksum Sum 0x7FD6 Number of opaque AS LSA 0. Checksum Sum 0x0 Number of DCbitless external and opaque AS LSA 0 Number of DoNotAge external and opaque AS LSA 0 Number of areas in this router is 2. 2 normal 0 stub 0 nssa External flood list length 0 Area BACKBONE(0) Number of interfaces in this area is 1 Area has no authentication SPF algorithm executed 11 times Area ranges are Number of LSA 5. Checksum Sum 0x30370 Number of opaque link LSA 0. Checksum Sum 0x0 Number of DCbitless LSA 3 Number of indication LSA 0 Number of DoNotAge LSA 0 Flood list length 0 Area 2 Number of interfaces in this area is 1 Area has no authentication SPF algorithm executed 9 times Area ranges are 131.252.215.32/27 Active(2) Advertise Number of LSA 9. Checksum Sum 0x4BA2B Number of opaque link LSA 0. Checksum Sum 0x0 Number of DCbitless LSA 1 Number of indication LSA 1 Number of DoNotAge LSA 0 Flood list length 0 BIG-BABY -------- -After summarization, in Area 1, we can see that Area Ranges are being reported for Big-Baby by the following two lines....... Area ranges are 131.252.215.64 255.255.255.224 Active(10) big-baby#sh ip ospf Routing Process "ospf 100" with ID 131.252.215.82 Supports only single TOS(TOS0) routes It is an area border router Summary Link update interval is 0:30:00 and the update due in 0:12:27 SPF schedule delay 5 secs, Hold time between two SPFs 10 secs Number of areas in this router is 2. 2 normal 0 stub Area 1 Number of interfaces in this area is 1 Area has no authentication SPF algorithm executed 9 times Area ranges are 131.252.215.64 255.255.255.224 Active(10) Link State Update Interval is 0:30:00 and due in 0:12:25 Link State Age Interval is 0:20:00 and due in 0:02:25 Area BACKBONE(0) Number of interfaces in this area is 1 Area has no authentication SPF algorithm executed 10 times Area ranges are Link State Update Interval is 0:30:00 and due in 0:12:14 Link State Age Interval is 0:20:00 and due in 0:02:14 ========================================= EFFECT OF ROUTE SUMMARIZATION ON DATABASE ========================================= DEXTER ------ BEFORE SUMMARIZATION>>>>>>> -Before summarization, the only type 3 LSAs (Summary net Link State) being advertised for Area 2 and 0 were: Summary Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 131.252.215.47 131.252.215.33 656 0x80000001 0x5CED 131.252.215.48 131.252.215.33 656 0x80000001 0x5CEB 131.252.215.79 131.252.215.82 287 0x80000004 0x34D7 131.252.215.80 131.252.215.82 287 0x80000004 0x20EB Summary Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.33 233 0x80000006 0xC9BA 131.252.215.79 131.252.215.33 1002 0x80000003 0x8597 131.252.215.80 131.252.215.33 1002 0x80000003 0x71AB AFTER SUMMARIZATION>>>>>>> -For area 2, after summarization, we can see that in the Type 3 LSA (Summary Net Link States), the only routes being advertised by Dexter are 131.252.215.0 and 131.252.215.32. - For Area 0, the only routes being advertised are 131.252.215.64 by big-baby and 131.252.215.32 by Dexter. dexter#sh ip ospf data OSPF Router with ID (131.252.215.33) (Process ID 100) Router Link States (Area 0) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.33 131.252.215.33 1594 0x80000006 0xC6B2 1 131.252.215.82 131.252.215.82 1638 0x8000000B 0x7CA8 1 Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 131.252.215.10 131.252.215.82 1638 0x80000009 0xBC83 Summary Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 131.252.215.32 131.252.215.33 701 0x80000001 0x9CCB 131.252.215.64 131.252.215.82 635 0x80000001 0x66C8 Router Link States (Area 2) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.33 131.252.215.33 1594 0x80000006 0x4FF4 1 131.252.215.49 131.252.215.49 41 0x80000008 0x738C 2 131.252.215.65 131.252.215.65 424 0x80000006 0xD312 1 131.252.215.67 131.252.215.67 1983 0x80000005 0xE414 1 Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.34 131.252.215.49 1597 0x80000005 0x6A34 131.252.215.50 131.252.215.65 424 0x80000005 0x4EAF Summary Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.33 1576 0x80000006 0xC9BA 131.252.215.64 131.252.215.33 640 0x80000001 0xB589 Summary ASB Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.33 131.252.215.33 1576 0x80000004 0x75F Type-5 AS External Link States Link ID ADV Router Age Seq# Checksum Tag 0.0.0.0 131.252.215.33 1602 0x80000001 0x7FD6 100 BIG-BABY -------- BEFORE SUMMARIZATION>>>>>>> Summary Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.82 641 0x8000000B 0xD490 131.252.215.47 131.252.215.82 641 0x80000002 0x79B4 131.252.215.48 131.252.215.82 641 0x80000002 0x79B2 Summary Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 131.252.215.47 131.252.215.33 1017 0x80000001 0x5CED 131.252.215.48 131.252.215.33 1017 0x80000001 0x5CEB 131.252.215.79 131.252.215.82 646 0x80000004 0x34D7 131.252.215.80 131.252.215.82 646 0x80000004 0x20EB AFTER SUMMARIZATION>>>>>> - In Area 1, after summarization, we can see that in the Type 3 LSA (Summary Net Link States) the only routes being advertised by Big-baby are 131.252.215.0 and 131.252.215.32. - In Area 0, after summarization, the only routes being advertised are 131.252.215.64 by big-baby and 131.252.215.32 by Dexter. - Before summarization, the only type 3 LSAs (Summary Net Link State) being advertised for Area 1 and 0 were: big-baby#sh ip ospf data OSPF Router with ID (131.252.215.82) (Process ID 100) Router Link States (Area 1) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.65 131.252.215.65 1869 0x80000005 0x497E 1 131.252.215.81 131.252.215.81 154 0x80000008 0x7AC4 2 131.252.215.82 131.252.215.82 1062 0x80000007 0x4B4D 1 Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.66 131.252.215.81 154 0x80000005 0xCEEE 131.252.215.82 131.252.215.82 1062 0x80000005 0xF4C6 Summary Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.82 1061 0x8000000B 0xD490 131.252.215.32 131.252.215.82 137 0x80000001 0xBB91 Summary ASB Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.33 131.252.215.82 1026 0x80000001 0x4AE3 Router Link States (Area 0) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.33 131.252.215.33 1035 0x80000006 0xC6B2 1 131.252.215.82 131.252.215.82 1077 0x8000000B 0x7CA8 1 Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 131.252.215.10 131.252.215.82 1077 0x80000009 0xBC83 Summary Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 131.252.215.32 131.252.215.33 142 0x80000001 0x9CCB 131.252.215.64 131.252.215.82 74 0x80000001 0x66C8 AS External Link States Link ID ADV Router Age Seq# Checksum Tag 0.0.0.0 131.252.215.33 1037 0x80000001 0x7FD6 100 RADIA ---- - Before Summarization, in type 3 LSA (Summary Net Link States) Dexter was advertising routes to 131.252.215.0, 131.252.215.79 and 131.252.215.80. - After Summarization, the only change is in the Type 3 LSA (Summary Net Link States) where only two routes, 131.252.215.0 and 131.252.215.64, are advertised by Dexter. radia#sh ip ospf data(AFTER SUMMARIZATION) OSPF Router with ID (131.252.215.49) (Process ID 100) Router Link States (Area 2) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.33 131.252.215.33 1548 0x80000006 0x4FF4 1 131.252.215.49 131.252.215.49 1793 0x80000007 0x758B 2 131.252.215.65 131.252.215.65 369 0x80000006 0xD312 1 131.252.215.67 131.252.215.67 1929 0x80000005 0xE414 1 Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.34 131.252.215.49 1543 0x80000005 0x6A34 131.252.215.50 131.252.215.65 370 0x80000005 0x4EAF Summary Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.33 1524 0x80000006 0xC9BA 131.252.215.64 131.252.215.33 587 0x80000001 0xB589 Summary ASB Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.33 131.252.215.33 1524 0x80000004 0x75F Type-5 AS External Link States Link ID ADV Router Age Seq# Checksum Tag 0.0.0.0 131.252.215.33 1549 0x80000001 0x7FD6 100 TONY ---- - The only difference is in the Summary Net Links States for Area 1 and Area 2 - In area 1, before Summarization, in type 3 LSA (Summary Net Link States) Big-Baby was advertising routes to 131.252.215.0, 131.252.215.47 and 131.252.215.48. - In area 1, after summarization, the only routes being advertised are for 131.252.215.0 and 131.252.215.32 (both by big-baby). - In Area 2, before Summarization, Dexter was advertising routes to 131.252.215.0, 131.252.215.79 and 131.252.215.80. - In Area 2, after summarization, the only routes being advertised are for 131.252.215.0 and 131.252.215.64 (both by Dexter) tony#sh ip ospf data (AFTER SUMMARIZATION) OSPF Router with ID (131.252.215.65) (Process ID 100) Router Link States (Area 1) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.65 131.252.215.65 108 0x80000006 0x477F 1 131.252.215.81 131.252.215.81 410 0x80000008 0x7AC4 2 131.252.215.82 131.252.215.82 1320 0x80000007 0x4B4D 1 Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.66 131.252.215.81 410 0x80000005 0xCEEE 131.252.215.82 131.252.215.82 1321 0x80000005 0xF4C6 Summary Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.82 1319 0x8000000B 0xD490 131.252.215.32 131.252.215.82 395 0x80000001 0xBB91 Summary ASB Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.33 131.252.215.82 1284 0x80000001 0x4AE3 Router Link States (Area 2) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.33 131.252.215.33 1306 0x80000006 0x4FF4 1 131.252.215.49 131.252.215.49 1552 0x80000007 0x758B 2 131.252.215.65 131.252.215.65 126 0x80000006 0xD312 1 131.252.215.67 131.252.215.67 1688 0x80000005 0xE414 1 Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.34 131.252.215.49 1301 0x80000005 0x6A34 131.252.215.50 131.252.215.65 126 0x80000005 0x4EAF Summary Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.33 1282 0x80000006 0xC9BA 131.252.215.64 131.252.215.33 346 0x80000001 0xB589 Summary ASB Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.33 131.252.215.33 1294 0x80000004 0x75F Type-5 AS External Link States Link ID ADV Router Age Seq# Checksum Tag 0.0.0.0 131.252.215.33 1319 0x80000001 0x7FD6 100 MRHORSE ------- - Before Summarization, in type 3 LSA (Summary Net Link state) Dexter was advertising routes to 131.252.215.0, 131.252.215.79 and 131.252.215.80. -After Summarization, the only change is in the Type 3 LSA (Summary Net Link States) where only two routes,131.252.215.0 and 131.252.215.64, are advertised by Dexter. mrhorse#sh ip ospf data (AFTER SUMMARIZATION) OSPF Router with ID (131.252.215.67) (Process ID 100) Router Link States (Area 2) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.33 131.252.215.33 1462 0x80000006 0x4FF4 1 131.252.215.49 131.252.215.49 1709 0x80000007 0x758B 2 131.252.215.65 131.252.215.65 285 0x80000006 0xD312 1 131.252.215.67 mrhorse.cat.pdx 1843 0x80000005 0xE414 1 Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.34 131.252.215.49 1458 0x80000005 0x6A34 131.252.215.50 131.252.215.65 286 0x80000005 0x4EAF Summary Net Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.33 1439 0x80000006 0xC9BA 131.252.215.64 131.252.215.33 502 0x80000001 0xB589 Summary ASB Link States (Area 2) Link ID ADV Router Age Seq# Checksum 131.252.215.33 131.252.215.33 1439 0x80000004 0x75F Type-5 AS External Link States Link ID ADV Router Age Seq# Checksum Tag 0.0.0.0 131.252.215.33 1473 0x80000001 0x7FD6 100 YAKOV ----- - Before Summarization, in type 3 LSA (Summary Net Link State), Big-Baby was advertising routes to 131.252.215.0, 131.252.215.47 and 131.252.215.48. - After Summarization, the only change is in the Type 3 LSA (Summary Net Link States) where only two routes,131.252.215.0 and 131.252.215.32, are advertised by BigBaby. yakov#sh ip ospf data (AFTER SUMMARIZATION) OSPF Router with ID (131.252.215.81) (Process ID 100) Router Link States (Area 1) Link ID ADV Router Age Seq# Checksum Link count 131.252.215.65 131.252.215.65 1993 0x80000005 0x497E 1 131.252.215.81 131.252.215.81 278 0x80000008 0x7AC4 2 131.252.215.82 131.252.215.82 1188 0x80000007 0x4B4D 1 Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.66 131.252.215.81 278 0x80000005 0xCEEE 131.252.215.82 131.252.215.82 1189 0x80000005 0xF4C6 Summary Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.0 131.252.215.82 1187 0x8000000B 0xD490 131.252.215.32 131.252.215.82 263 0x80000001 0xBB91 Summary ASB Link States (Area 1) Link ID ADV Router Age Seq# Checksum 131.252.215.33 131.252.215.82 1152 0x80000001 0x4AE3 Type-5 AS External Link States Link ID ADV Router Age Seq# Checksum Tag 0.0.0.0 131.252.215.33 1175 0x80000001 0x7FD6 100