Network layer problems include any problem which involves a Layer 3
protocol, both routed protocols and routing protocols. This module will focus
primarily on IP routing protocols. Issues concerning routed protocols, such as
IP, and other Layer 3 IP protocols, are discussed in the other modules.
Network layer problems may also include issues at the other layers.
Configuring routing over a nonbroadcast multiaccess (NBMA) or dialup network
can involve specific configuration and troubleshooting issues. Because these
configurations involve a specific Layer 2 technology such as Frame Relay, ISDN,
and so on, routing problems involving these technologies was discussed in the
module "Layer 2 Troubleshooting".
This module will focus on
the most common troubleshooting issues regarding both static routing and
dynamic routing protocols. Troubleshooting dynamic routing protocols is
separated by common issues pertaining to most routing protocols, such as Layer
1 issues, incorrect network statements, and by routing protocols including RIP,
EIGRP, OSPF, IS-IS, and BGP. Troubleshooting redistribution issues with routing
protocols are also discussed in this module.