Shulou(Shulou.com)06/02 Report--

Basic theory of OSPF, single area configuration

OSPF Multiarea configuration, ABR,

Ospf routing Typ

Internal: declared by network

Intra-area

Inter-area

External: announced by redistribution (redistribute | import-route)

# 5 LSA can be transmitted anywhere in the OSPF network

Special areas: 5 types of LSA-stub: 4 and 5 types are not allowed The ABR of the area automatically generates a default route (inter-area) to the area. All routers in the area need to be configured with stub. Ospf 1 area 34 stub-totally stub: type 3, 4 and 5 LSA are not allowed in complete stub areas But there is a special three types of LSA Indicates that the default route only needs to be configured on ABR in the stub area at this time: ospf 1 area 34 stub no-summary Normal area:-Type 1 of LSA-any OSPF router will generate, Will be generated in every area connected. The route calculated by type 1 LSA belongs to intra-area route; 2-3-only ABR can be generated (0 [intra-area / inter-area]-- > non-0; non-0 [intra-area]-- > 0 ) represents the route between areas, and the LSA changes during transmission: each time an ABR passes, the advertised router changes. 4-5-only ASBR can be generated; represents an external route, and the LSA is unchanged during transmission; prefix/mask [preference/cost] type, via next-hop, interface OSPF special area: NSSA: no so stub area, this area does not allow type 4 or 5 LSA, but allows external routes to exist External routes are represented by type-7 LSA. 7 types of LSA can only exist in the NSSA region. That is, only 1, 2, 3, 7-Application scenarios-configuration: NSSA is configured on every router in the area. Ospf 1 area 14 nssa the ABR of this area will automatically generate a default route to the NSSA area, which is represented by type 7 LSA, and the ABR of this area will convert the external route represented by type 7 LSA into type 5 LSA, so that other OSPF areas (normal) can obtain the external route entry. And in the one-way conversion of 7 to 5, only the ABR with large RID in the NSSA area can be finally converted. Compared with NSSA, totally NSSA also lacks three types of detailed routes represented by LSA, that is, there are only 1, 2, 7; only through a default route represented by type 7 LSA automatically generated by ABR in NSSA area, the interworking between NSSA area and other areas and external routes can be realized. Configuration command: just need to do it in all the ABR in the NSSA area. Ospf 1 area 14 nssa no-summary OSPF discontiguous area solution:-construct ABR so that routes to this non-backbone area exist as internal routes in other areas; # on routers connecting multiple non-backbone areas, an OSPF neighbor relationship with area 0 is established by re-linking a "physical link" The OSPF neighbor relationship established by # virtual-link through the virtual link always belongs to area 0; the establishment of the virtual link depends on the area where the underlying real link is located to transmit OSPF packets (hello, etc.). Therefore, if the underlying "traversal / transmission area" is unstable, it will lead to the instability of the upper "virtual link", which will affect the stability of the backbone area of the whole network. Therefore, this approach is generally not recommended. If you have to use it, it's only a temporary solution. -configuration: configure the following command in the real ABR of the router and transport area that wants to be ABR: R1: ospf 1 area 14 vlink-peer 4.4.4.4 / / here It must be the RID R4 of the other router: ospf 1 area 14 vlink-peer 1.1.1.1 / / must not be written as the interface IP of the other device. You must ensure that the OSPF neighbor relationship in area 14 is intact. Display ospf vlink / / look at the OSFP neighbor relationships established locally over virtual links-build different OSPF processes so that the delivery of routes is presented as external routes. R4: create a new OSPF process-ospf 8 ospf 8 / / R4 establishes a neighbor relationship with R7 through ospf 8. Area 47 network 192.168.47.4 0.0.0.0 quit import-route ospf 1 ospf 1 / / R4 establishes a neighbor relationship with R1 through ospf 1. Analysis of import-route ospf 8 OSPF LSA:

Basic introduction to OSPF

OSPF single area / Multiarea

OSPF Special area (import-route)

OSPF discontinuous regions (some non-backbone areas are not directly connected to backbone areas)

Solution-1: virtual-link-what is a virtual link called Virtual link? Is a virtual link, not a real physical link, and always belongs to OSPF area 0; why use virtual-link? In order to solve the communication problem between the non-backbone areas which are not directly connected to the backbone in the OSFP network. Configuration implementation: where is it configured? # configure on a router connecting multiple non-backbone areas and on an ABR in the same area as the router;-how to configure it? R5: ospf 1 area 1 vlink-peeer 3.3.3.3 R3: ospf 1 area 1 vlink-peeer 5.5.5.5-how to verify? Display ospf vlink-> View the status of neighbor relationships established through vlink; display ospf brief-- > View the role of the OSPF router; and display ip routing-table-- > look at the router routing table to confirm that all routes have been obtained. Solution-2: different OSPF processes are redistributed on routers that connect multiple non-zero areas at the same time, create two different OSPF processes, and then redistribute OSPF between processes.

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Link state: ISIS OSPF OSPF route summary 1. What is "route summary" means that when a route is sent, multiple route entries that need to be sent are summarized into "a few" route entries. For example: R1mura-> R2 192.168.1.0 Universe 24 192.168.1.0 Grey 24 192.168.2.0 Universe 24 192.168.2.0 Universe 24 192.168.3.0 192.168.3.0Universe 24 192.168.4.0Universe 24 192.168.4.0Accord 24 192.168.0.0Universe 16 summary essence: send summary only Do not send details [only send summary LSA to suppress the generation of detail LSA] 2. Why to say that "route summary" # can save network resources and equipment resources; # can enhance the stability of the network, pre-sales engineer technology 1. After-sales engineer: junior, intermediate, advanced 2. Project Manager 3. Project Director 3. When using "Route Summary" # to transmit a large number of route entries, consider the optimal use of resources; # when considering the stability of the network, 4. How to use / configure route summarization class 1.3 LSA summaries; # where do I do it? In which region is the ABR that generates the detail LSA; # configured? In the summarized area, configure; # how to configure? R3: ospf 1 area 1 abr-summary 192.168.0.0 255.255.0.0 # how to verify? Display ospf lsdb 2. 5 LSA summary; # where do I do it? How to configure the ASBR that generates the details LSA? R5: ospf 1 asbr-summary 192.168.0.0 255.255.0.0 # how to verify? Display ospf lsdb 192.168.34.0 X.X.X.X/n 24 192.168.45.0 X.X.X.X/n 24 192.168.0 Charpy 16 192.168.56.0 Universe 24 192.168.67.0 how to calculate the summary route: 1. Routing consists of two parts: prefix / mask 2. The determination of the common "prefix" (in the summary function, we only focus on the "prefix"): find the common part of the prefix of all detailed routes-from left to right-the same bit, unchanged;-different bits, 0;-meet the first different bit, stop, and the rest are treated differently. Exercise: 192.168.1.0 Universe 24 192.168.2.0 Accord 24 192.168.3.0 Accord 24 192.168.4.0 Universe 24192.168. 0000 0001.0192.168. 0000 0010.0192.168. 0000 0011.0192.168. 0000 0100.0 192.168.0000 0xxx.192.168.0.0Universe 21 route filtering: 1. Grab route (prefix / mask) # imprecise-only prefix; # precise grab-grab prefix and mask 2. Invocation strategy 192.168.1.0 192.168.X.0 24 192.168.0.0 192.168.X.0 24 192.168.3.0 max 24 192.168.2.0 ash 24 192.168.5.0 max 24 192.168.4.0 max 24 192.168.7.0 max 24 192.168.6.0 0001 0000 0011 0000 0101 0000 0111X = 0000 0001 routing prefix matching principle: 1. Look from left to right; 2. The same bit, unchanged, write directly; 3. Different bits are written directly as 0; to successfully match a route (prefix), you have to use the wildcard character 1. An one-to-one correspondence between a wildcard and a common prefix. In wildcards, the invariant bits of the common prefix correspond to write 0; 3. In wildcards, the bits that vary with the common prefix correspond to write 1; 192.168.1.01100 0000. 1010 1000. 0000 0001. 0000 0000-192.168.1.00000 0000. 0000 0000. 0000 0110. 0000 0000-0.0.6.0192.168.1.0 0.0.6.0-> acl 2000 rule 5 permit 192.168.1.0 0.0.6.0 so the configuration idea is as follows: 1. Matching route; acl 2000 rule 5 deny 192.168.1.0 0.0.6.0 2. Call strategy: ospf 1 filter-policy 2000 import IPv6 RIPng OSPFv3 BGP ACL self-summary: lingk-state link-state routing protocol route summary: when sending route entries, summarize multiple route entries into a few routing items: 1 save network resources and device resources 2 enhance the stability of the network essence: send only summary entries Do not send details when to use route summary? When there are a large number of routing entries transmitted, taking into account the optimal use of resources and the stability of network resources, the configuration of type 1 LSA that cannot be summarized needs to be configured on the ABR of the aggregated area: (type 3 LSA summary) ospf 1 area 1 abr-summary 192.168.0.0 255.255.0.0 restart after saving Verify: display ospf lsdb (view ospf database information) OSPF address summary configuration: (type 5 LSA summary) ospf 1 asbr-summary 192.168.0.0 255.255.0.0 save and restart, verify: display ospf lsdb (view ospf database information)

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