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Bài giảng Mạng máy tính nâng cao (Advance computer networks) - Chapter 11: Open Shortest Path First

The objectives of this chapter: Describe the background and basic features of OSPF. Identify and apply the basic OSPF configuration commands. Describe, modify and calculate the metric used by OSPF. Describe the Designated Router/Backup Designated Router (DR/BDR) election process in multiaccess network. Describe the uses of additional configuration commands in OSPF. | Chapter 11 Open Shortest Path First MẠNG MÁY TÍNH NÂNG CAO Objectives Describe the background and basic features of OSPF. Identify and apply the basic OSPF configuration commands. Describe, modify and calculate the metric used by OSPF. Describe the Designated Router/Backup Designated Router (DR/BDR) election process in multiaccess networks. Describe the uses of additional configuration commands in OSPF. Introduction Introduction to OSPF Background of OSPF Began in 1987 1989 OSPFv1 released in RFC 1131 This version was experimental & never deployed 1991 OSPFv2 released in RFC 1247 1998 OSPFv2 updated in RFC 2328 1999 OSPFv3 published in RFC 2740 Introduction to OSPF OSPF Message Encapsulation OSPF packet type There exist 5 types OSPF packet header Contains - Router ID and area ID and Type code for OSPF packet type IP packet header Contains - Source IP address, Destination IP address, & Protocol field set to 89 Introduction to OSPF OSPF Message Encapsulation Data link frame header . | Chapter 11 Open Shortest Path First MẠNG MÁY TÍNH NÂNG CAO Objectives Describe the background and basic features of OSPF. Identify and apply the basic OSPF configuration commands. Describe, modify and calculate the metric used by OSPF. Describe the Designated Router/Backup Designated Router (DR/BDR) election process in multiaccess networks. Describe the uses of additional configuration commands in OSPF. Introduction Introduction to OSPF Background of OSPF Began in 1987 1989 OSPFv1 released in RFC 1131 This version was experimental & never deployed 1991 OSPFv2 released in RFC 1247 1998 OSPFv2 updated in RFC 2328 1999 OSPFv3 published in RFC 2740 Introduction to OSPF OSPF Message Encapsulation OSPF packet type There exist 5 types OSPF packet header Contains - Router ID and area ID and Type code for OSPF packet type IP packet header Contains - Source IP address, Destination IP address, & Protocol field set to 89 Introduction to OSPF OSPF Message Encapsulation Data link frame header Contains - Source MAC address and Destination MAC address Introduction to OSPF OSPF Packet Types Hello Protocol OSPF Hello Packet Discover OSPF neighbors & establish adjacencies Advertise guidelines on which routers must agree to become neighbors Used by multi-access networks to elect a designated router and a backup designated router Hello Protocol OSPF Hello Packet Hello Protocol OSPF Hello Packet Contents of a Hello Packet router ID of transmitting router OSPF Hello Intervals Usually multicast (224.0.0.5) By default, OSPF Hello packets are sent every 10 seconds on multiaccess and point-to-point segments and every 30 seconds on non-broadcast multiaccess (NBMA) segments (Frame Relay, X.25, ATM). OSPF Dead Intervals This is the time that must transpire before the neighbor is considered down Default time is 4 times the hello interval Hello Protocol Electing a DR and BDR To reduce the amount of OSPF traffic on multiaccess networks, OSPF elects a Designated Router (DR) and Backup Designated .