Category Archives: Routing

Troubleshoot NAT

Posted on April 27, 2010 by Judson Bishop

Definitions NAT Types Static NAT — A one-to-one mapping of private to public IP addresses, best used for a device that needs access from outside the AS. Dynamic NAT — A dynamic one-to-one mapping between private and public IP addresses, … Continue reading →

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Troubleshooting Spanning Tree Protocol

Posted on April 26, 2010 by Judson Bishop

Spanning Tree Protocol Basics: In a layer 2 environment with no routing, active redundant paths are neither allowed no desirable, because the can cause loops. Because a switch only segments collision domains it does not segment broadcast domains. STP helps … Continue reading →

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Troubleshoot Router Performance

Posted on April 16, 2010 by Judson Bishop

There are three general causes of router performance issues: 1. High CPU load 2. Router packet switching mode 3. Excessive memory use Processes that can be a cause of high CPU load: • ARP Input process — Heavy traffic load … Continue reading →

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Troubleshoot BGP

Posted on April 13, 2010 by Judson Bishop

2010-04-13 16:07:12 Troubleshoot BGP BGP is a path-vector routing protocol. Routes are tracked in terms of the AS they pass through, and routers avoid loops by rejecting routes that have already passed through their AS. Definitions Synchronization — Before iBGP … Continue reading →

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Troubleshoot OSPF

Posted on April 12, 2010 by Judson Bishop

My notes for EIGRP felt like I was just regurgitating the Key Points from the book. So with OSPF I read the book and looked at the command output, then decided to copy my notes from the BSCI and edit … Continue reading →

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Layer 3 Troubleshooting

Posted on April 4, 2010 by Judson Bishop

Cisco Express Frowarding (CEF) The two main components of CEF are the forwarding information base (FIB) and the adjacency table. IP routing table is maintained by a router’s control plane. CEF operates in the data plane. Forwarding Information Base (FIB) … Continue reading →

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Cisco Express Forwarding and Layer 2 to Layer 3

Posted on April 4, 2010 by Judson Bishop

2010-04-04 14:21:36 Cisco Express Forwarding (CEF) The two main components of CEF are the forwarding information base (FIB) and the adjacency table. IP routing table is maintained by a router’s control plane. CEF operates in the data plane. Forwarding Information … Continue reading →

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Layer 3 Switch Troubleshooting

Posted on April 2, 2010 by Judson Bishop

The big topics of this chapter include HSRP, VRRP, GLBP, TCAM and the port error table. I broke out my notes from the BCMSN and I’ll summarize each topic from them, then move into the troubleshooting of each protocol. Hot … Continue reading →

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Making the Transition

Posted on March 29, 2010 by Judson Bishop

How do you know you have crossed over from a sysadmin to a network admin? When you log on to a Linux server and type “en.” There is a story here. I used to login to a router or switch … Continue reading →

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Network Maintenance

Posted on March 18, 2010 by Judson Bishop

I am going to admit that I have not been studying for the TSHOOT exam very diligently. In my mind it is a topic that we deal with on a daily basis and what could the book teach me. (sarcasm) … Continue reading →

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