OSPF (Open Shortest Path First) is an internal gateway protocol (Interior Gateway Protocol, IGP), a link status routing protocol for decision route in a single autonomous system (AS).
OSPF creates a link status database through the status of the network interface between the router, generates the shortest path tree, and each OSPF router uses these shortest path to construct the routing table. See RFC2178 in the document.
1. What is the characteristics of an OSPF network? OSPF is a link state routing protocol, relative to the distance vector routing protocol, which uses the area boundary router and a backbone area, the network type defined by OSPF is: point-to-point, broadcast, non-broadcast, point to multi-point, etc.
2, what is the regional border router (ABR)? A autonomous system is divided into multiple regions, and one regional boundary router connects two or more areas in the same autonomous system.
3, what is the backbone area? The backbone area is a region connected to the regional boundary router, usually one region to the other area can only pass through the backbone area.
4, what type of router in the OSPF network: backbone router, regional boundary router, internal router, autonomous system boundary router (which connects two autonomous systems).
5 Route Summary: The set of routes generated by the regional boundary router and the autonomous system boundary router, which will notify the adjacent router. If the network number in one area is continuous, the area boundary road accessor and the autonomous system boundary router can be configured to be a notification route, and the summary routing is the range of network numbers. Routing summary reduces the size of the link status database.
6 Region Type:
Snaps: A area where an external route does not flow. The external route refers to any non-OSPF initiated route, such as a route released by other routing protocols is external route, and external routes are usually flooded on an OSPF Internet. If there is only one exit in one area, there is almost no reason to flow a lot of routing into the area, and only one default LSA route to this area. Through the route. The short bald area can reach a terminal other than the autonomous region. Complete short breath. In addition to not entering the exterior routing, even if the OSPF summary routes do not enter the area.
7. Global settings for CSICO Router Commands
Task Command Specifies the NETWORK Address Wildcard-Mask Area Area-ID2 connected to the router using the OSPF protocol Router OSPF Process-ID1 Specifies Node Address Node Address Node Address Node Address Note: 1. OSPF Routing Process Process-id You must specify a range 1-65535, multiple OSPF processes can be configured on the same router, but it is best not to do so. Multiple OSPF processes require a copy of multiple OSPF databases that must run a copy of multiple shortest path algorithms. The Process-ID only works within the router, and the Process-ID of different routers can be different. 2, Wildcard-Mask is the counter code of the subnet mask, the decimal number of the network area ID area-ID in 0-4294967295, or X.x.x.x with IP address format. When the network area ID is 0 or 0.0.0.0, it is the main domain. The routers of different network areas are routing information through the main sanctuary. 8. Basic Configuration example: Router1:!! Interface ethernet 0 ip address 192.1.0.129 255.255.255.192 interface serial 0 ip address 192.200.10.5 255.255.255.252 router ospf 100 network 192.200.10.4 0.0.0.3 area 0 network 192.1.0.128 0.0.0.63 area ! 1 Router2:!! interface ethernet 0 ip address 192.1.0.65 255.255.255.192 interface serial 0 ip address 192.200.10.6 255.255.255.252 router ospf 200 network 192.200.10.4 0.0.0.3 area 0 network 192.1.0.64 0.0.0.63 area 2! router3:! interface ethernet 0 ip address 192.1.0.130 255.255.255.192 router ospf 300 network 192.1.0.128 0.0.0.63 area 1 Router4:!! interface ethernet 0 ip address 192.1.0.66 255.255.255.192 router ospf 400 network 192.1.0.64 0.0. 0.63 Area 1! Related debugging command: Debug ip ospf Events debug ip ospf packet show ip ospf show 帖子 ospf Database show ip ospf interface show ip ospf neighbor show ip route 9. Use authentication For security reasons, we can be in the same OSPF area The function of authentication is enabled on the router, and only the router of the same area of authentication can be notified to each other. By default, OSPF does not use zone verification. Authentication feature, plain text authentication and message summary (MD5) authentication can be enabled by two ways. Plain text authentication The authentication password is plain text, which will be determined by the network detector, so it is not safe, not recommended. And Message Summary (MD5) Authentication To encrypt your password before transferring authentication password, so it is generally recommended to use this method for authentication. When using authentication, all router interfaces in the area must use the same authentication method.
For the trial authentication, you must configure the password for each router interface for the area in the router interface configuration mode. Task Command Specify Authentication Area Area-ID Authentication [Message-Digest] Using plain text authentication IP OSPF Authentication-Key Password Using Message Summary (MD5) Authentication IP OSPF Message-Digest-Key Keyid MD5 Key The following verification settings The example, the example network distribution and address allocation environment are the same as those of the above basic configuration, just in the area 0 of Router1 and Router2, using authentication functions. : Example 1. plaintext authentication Router1:!! Interface ethernet 0 ip address 192.1.0.129 255.255.255.192 interface serial 0 ip address 192.200.10.5 255.255.255.252 ip ospf authentication-key cisco router ospf 100 network 192.200.10.4 0.0. 0.3 area 0 network 192.1.0.128 0.0.0.63 area 1 area 0 authentication Router2:!!! interface ethernet 0 ip address 192.1.0.65 255.255.255.192 interface serial 0 ip address 192.200.10.6 255.255.255.252 ip ospf authentication-key cisco router ospf 200 network 192.200.10.4 0.0.0.3 area 0 network 192.1.0.64 0.0.0.63 area 2 area 0 authentication Example 2. The message digest (MD5) authentication:! Router1:! interface ethernet 0 ip address 192.1.0.129 255.255.255.192 interface serial ! 0 ip address 192.200.10.5 255.255.255.252 ip ospf message-digest-key 1 md5 cisco router ospf 100 network 192.200.10.4 0.0.0.3 area 0 network 192.1.0.128 0.0.0.63 area 1 area 0 authentication message-digest Router2!: Interface Ethernet 0 IP Address 192.1 .0.65 255.255.255.192! Interface serial 0 ip address 192.200.10.6 255.255.255.252 ip ospf message-digest-key 1 md5 cisco! Router ospf 200 network 192.200.10.4 0.0.0.3 area 0 network 192.1.0.64 0.0.0.63 area 2 area 0 Authentication Message-Digest! Related debugging command: debug ip ospf adj beug ip OSPF Events
