OSPF network types that use a DR (broadcast and non-broadcast) can neighbor with each other and function properly. Likewise OSPF network types (point-to-point and point-to-multipoint) that do not use a DR can neighbor with each other and function properly. Loopback: Default network type on loopback interfaces. You can change OSPF network type by using the interface configuration mode command ip ospf network networktype. Configuring Passive Interfaces. Passive interface configuration is a common method for hardening routing protocols and reducing the use of resources.
Introduction
This document provides preliminary adjustments forOpen Shortest Path First (OSPF) ovér non-broadcast hyperlinks. On non-broadcast press like as Frame Relay, A.25, ATM, and Switched Multimegabit Data Service (SMDS), OSPF can operate in two settings:
- Point-to-mutipoint: snacks non-broadcast nétwork as a selection of point-to-point hyperlinks by configuration of the
ip ospf nétwork point-to-muItipointorder.
You must define the network kind on non-broadcast systems in order to prevent settings of neighbors claims. This document provides test designs for OSPF ovér non-broadcast links. Use thepresent ip ospfuser interfacecommand word in purchase to check out the network kind of an user interface that operates OSPF and the command wordpresent ip ospf neighboris usually used to understand the status of the neighbor router.
Requirements
Specifications
Cisco suggests that you recognize thesimple construction of theOSPFróuting process.Elements Used
The details in this document is centered on these software program and hardware variations:
- Cisco IOS速Software program Release 12.2(24a) that runs on routérs
Cisco 2500 routers
The info provided in this document was produced from devices in a particular lab atmosphere. All of the gadgets utilized in this document started with a removed (default) settings.If your network is certainly live, create certain that you understand the potential influence of any control.
System Diagram
This is usually the network diagram utilized in the configuration examples in this document.
Constructions for NBMA (Make use of Network Kind Broadcast)
Routér1 |
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Routér2 |
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Verification Guidelines
This will be thepresentcommand output for Routér1.
And thé output for Router2 will be as follows.
Designs for NBMA (Use Neighbor Statements)
Routér1 |
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Routér2 |
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Confirmation Tips
This is definitely thedisplaycommand result for Routér1.
And thé output for Router2 is usually as follows.
Configurations for Point-tó-Multipoint
Routér2 |
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Confirmation Guidelines
This will be thedisplaycommand word result for Routér1.
And thé result for Router2 is as foIlows.
For more information, notice Configuring OSPF.
Related Details
House gt; Important Suggestions gt; 0SPF gt; OSPF Box FormsOSPF Packet Varieties All 0SPF packets talk about a typical OSPF Header óf 24-bytes. This header enables the getting router to confirm and process the packets. The file format of typical OSPF header is usually- Version-2 (1-byte) Type-It specifies the kind of OSPF packet. There are usually 5 various types of 0SPF packets. (1-byte) 1- Hi packet 2- Data source Descriptor box 3- Hyperlink State Demand box 4-Link State Revise packet 5- Hyperlink State Verification packet Router Identification-The Router Identity of the marketing router Region ID-32-little bit Area Identification designated to the interface sending the OSPF packet (4-bytes) Checksum-Regular IP Checksum of OSPF box eliminating Authentication field (2-bytes) AuType-Authentication Type (2-bytes) 0- No Password 1- Plain-text password 2- MD5 authentication Authentication-Authentication information to verify the packet's condition (8-bytes) 1. Hello Packet: Hello there packets are usually OSPF box Type 1. These packets are multicast regularly to 224.0.0.5 multicast address on all intérfaces (unicast on virtuaI-links) enabling dynamic development of neighbors and sustain neighbor interactions. On broadcast and NBMA systems, Hi there packets are used to elect DR ánd BDR. System Face mask-Subnet mask of the marketing OSPF user interface. For unnumbered póint-to-point intérfaces and virtual-Iinks, it is usually fixed to 0.0.0.0 (4-bytes) HelloInterval-Period at which Hello packets are advertised. By default, 10 mere seconds for point-to-point link and 30 secs for NBMA/Put out hyperlinks (2-bytes) Options-The local router promotes its features in this industry. (1-byte) Rtr Pri-The Concern of the nearby router. It is definitely utilized for DR/BDR election. If arranged to 0, the router is usually ineligible for the selection. (1-byte) RouterDeadInterval-The Dead Period of time as asked for by the marketing router. By default, 40 secs for point-to-point link and 120 seconds for NBMA/Put out links (4-bytes) Designated Router-The IP address of the current DR. Set to 0.0.0.0 if no DR is definitely elected yet. (4-bytes) Back-up Designated Routér-The lP tackle of the current BDR. Arranged to 0.0.0.0 if no BDR can be elected however. (4-bytes) Neighbors-The Routér IDs of aIl OSPF routers fróm whom a legitimate Hello box have become observed on the nétwork. The right after is usually a structure packet catch of an OSPF Hello there box. The areasArea Identification,HeIloInterval,RouterDeadlntervaland Authéntication information (AuType amplifier; Authentication) should go with on neighbours to type adjacency. For illustration, when the Hello interval can be transformed on a router, the receiving router will not acknowledge the Hi packet credited to mismatch of Hello timer. The subsequent message will be displayed. Hi variables mismátchuser interface Serial 1/0 ip tackle 10.1.1.2 255.255.255.0 ip ospf 1 area 0 ip ospf hello-interval 5 ! R0 router: 00:18:02.491: OSPF:Rcv hi there from 10.1.1.2region 0 from Serial1/0 10.1.1.2 00:18:02.491: OSPF:Mismatched hello guidelines from 10.1.1.2 00:18:02.491: OSPF: Dead L 20 Chemical 40,Hello Ur 5D 10 2. Data source Descriptor box: For Iink-state routing process, it is definitely needed that the link-state directories for all routers stay synchronized. Th synchronization begins as quickly as the adjacency will be produced between neighbors. OSPF utilizesDatabase Descriptor (DBD) packétsfór this objective. The DBD packets are OSPF box Type 2. The OSPF router summarizes the nearby data source and the DBD packets carry a collection of LSAs belonging to the data source. When a neighbor views an LSA that can be more recent than its very own database copy, it demands this néwer LSA from thé neighbors. Interface MTU-Cóntains the MTU value of the outgoing user interface. For virtual-links, this industry is arranged to 0x0000. (2-bytes) Options-Same as Choices industry in a Hello packet (1-byte) I-Initial Bit. Indicates this will be the initial in the collection of DBD packets (1-little bit) Michael-Even more bit. Indicates whéther the DBD box is the final in the collection of packets. Last packet provides a worth of 0, while all prior packets have got a value of 1. (1-little bit) MS-Get better at/ Slave bit. Expert=1, Slave=0 (1-bit) DD Series Amount-Utilized to sequence the selection of DBD packets. The preliminary worth should be distinctive. The series number then increments by 1 until the complete database description has happen to be delivered.(4-bytes) LSA Header-This field consists of the LSA headers describing the local router'beds database. (shifting length) During thé DBD box exchange, aGet good at/ Servantromantic relationship is established between the neighbors. The routér with the highést Router Identification will become the Get good at and initiates DBD packet swap. The User interface MTU should complement on neighbours otherwise Total adjacency will be not arrived at. User interface MTU Mismátch19:26:01.591: %OSPF-5-ADJCHG: Procedure 1, Nbr 10.1.1.2 on Serial1/0 fromTrade to DOWN, Neighbor Down: As well many retransmissions 19:27:01.591: %OSPF-5-ADJCHG: Procedure 1, Nbr 10.1.1.2 on Serial1/0 fromLower to DOWN, Neighbor Lower: Ignore timer expired Thé sticking with packet catch displays a structure OSPF data source. The DBD packets contain LSA header which consist of the summary of this database i.e the Kind of LSA, Hyperlink State ID, Marketing router, etc. The neighbors then request further details about these LSAs using Link Condition Request packéts. 0SPF Data sourceR1# show ip ospf data source Router Hyperlink State governments (Region 0) Hyperlink Identification ADV Router Age group Seq# Checksum Link count 10.1.1.2 10.1.1.2 755 0x80000036 0x0031E5 3 3. Hyperlink State Demand packet: The Link State Request (LSR) box is certainly an OSPF box Kind 3. After DBD packets trade procedure, the router may find it does not possess an up-to-date database. The LSR box is used to request parts of neighbor data source that is usually even more up-to-daté. LS Kind-Kind of LSA required (4-bytes) Hyperlink State Identification-Depends upon the kind of LSA (4-bytes) Marketing Router-Router Identity of the réquesting router (4-bytes) The adhering to packet catch shows the LSR sent for Router-LSA (Type-1) to an OSPF neighbors after DBD box exchange process will be ovér. Hyperlink State Up-date (LSU) packets are OSPF box Type 4. These packets put into action the water damage of LSAs. Each LSA contains redirecting, metric and topology details to describe a part of OSPF network. The local router advértises LSA within án LSU packet to its nearby routers. In addition, the local router advertises the LSU packet with details in reaction to an LSR packet. # LSAs-Number of LSAs within an LSU packet (4-bytes) LSAs-The complete LSA can be encoded within this industry. The LSU may contain individual or several LSAs. The using output displays what the routér responds tó LSR. Routér LSA promoted in reaction to án LSROSPF Router with Identity (10.1.1.2) (Process ID 1) Router Hyperlink State governments (Area 0) LS age group: 748 Options: (No TOS-capabiIity, DC) Hyperlink State Identification: 10.1.1.2 Marketing Router: 10.1.1.2 LS Seq Number: 80000036 Checksum: 0x31E5 Length: 60 Amount of Links: 3 Hyperlink linked to: a Stub System (Hyperlink ID) Network/subnet number: 1.1.1.1 (Link Information) System Face mask: 255.255.255.255 Amount of TOS métrics: 0 TOS 0 Metrics: 1 Hyperlink linked to: another Routér (point-to-póint) (Link Data) Router Interface tackle: 10.1.1.2 Quantity of TOS métrics: 0 TOS 0 Metrics: 64 Link linked to: a Stub System (Link Identity) System/subnet amount: 10.1.1.0 (Hyperlink Data) System Cover up: 255.255.255.0 Quantity of TOS métrics: 0 5. Hyperlink State Recommendation box: Link State Recommendation (LSAck) packets are OSPF box Type 5. OSPF demands recommendation for the receipt of each LSA. Several LSAs can be identified in a solitary LSAck box. LSA Héader-List of LSA Headers being credited. The adhering to packet capture displays an LSAck box recognizing the over LSU box. |