Chapter 8: OSPF
Instructor Materials
CCNP Enterprise: Core Networking
,Chapter 8 Content
This chapter covers the following content:
• OSPF Fundamentals - This section provides an overview of
communication between OSPF routers.
• OSPF Configuration - This section describes the OSPF configuration
techniques and commands that can be executed to verify the exchange
of routes.
• Default Route Advertisement - This section explains how default
routes are advertised in OSPF.
• Common OSPF Optimizations -This section reviews common OSPF
settings for optimizing the operation of the protocol.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2
,OSPF Fundamentals
• The Open Shortest Path First (OSPF) protocol is a nonproprietary Interior Gateway
Protocol (IGP) that overcomes the deficiencies of other distance vector routing
protocols and distributes routing information within a single OSPF routing domain.
• OSPF introduced variable-length subnet masking (VLSM), which supports classless
routing, summarization, authentication, and external route tagging.
• There are two main versions of OSPF in production networks today: OSPF Version 2
(OSPFv2) which supports IPv4, OSPF Version 3 (OSPFv3) which supports IPv6.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3
, OSPF Fundamentals
LSAs, LSDB, and SPT
• OSPF sends link-state advertisements (LSAs) to neighboring routers. LSAs contain
the link state and link metric. The received LSAs are stored in a local database called
the link-state database (LSDB). The LSDB provides the topology of the network.
The SPT contains all network destinations within the OSPF domain.
• Figure 8-1 shows a simple OSPF topology and the SPT from R1’s and R4’s
perspective. Notice that the local router’s perspective will always be the root (top of
the tree).
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 4
Instructor Materials
CCNP Enterprise: Core Networking
,Chapter 8 Content
This chapter covers the following content:
• OSPF Fundamentals - This section provides an overview of
communication between OSPF routers.
• OSPF Configuration - This section describes the OSPF configuration
techniques and commands that can be executed to verify the exchange
of routes.
• Default Route Advertisement - This section explains how default
routes are advertised in OSPF.
• Common OSPF Optimizations -This section reviews common OSPF
settings for optimizing the operation of the protocol.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2
,OSPF Fundamentals
• The Open Shortest Path First (OSPF) protocol is a nonproprietary Interior Gateway
Protocol (IGP) that overcomes the deficiencies of other distance vector routing
protocols and distributes routing information within a single OSPF routing domain.
• OSPF introduced variable-length subnet masking (VLSM), which supports classless
routing, summarization, authentication, and external route tagging.
• There are two main versions of OSPF in production networks today: OSPF Version 2
(OSPFv2) which supports IPv4, OSPF Version 3 (OSPFv3) which supports IPv6.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3
, OSPF Fundamentals
LSAs, LSDB, and SPT
• OSPF sends link-state advertisements (LSAs) to neighboring routers. LSAs contain
the link state and link metric. The received LSAs are stored in a local database called
the link-state database (LSDB). The LSDB provides the topology of the network.
The SPT contains all network destinations within the OSPF domain.
• Figure 8-1 shows a simple OSPF topology and the SPT from R1’s and R4’s
perspective. Notice that the local router’s perspective will always be the root (top of
the tree).
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 4
