CCNP Recertification

CCNP completely redone

This is the biggest change I’ve seen in the CCNP: BSCI becomes ROUTE BCMSN becomes SWITCH ISCW and ONT become TSHOOT Looks like more IPv6 content, multicast and IS-IS are gone, and more focus on simulations and troubleshooting. The old exams are phased out on July 31, so if you have can make it by that date, get cracking! Exams are [...]

Content Copyright Sean Walberg

CCNP completely redone

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More command line NetFlow reports

As I dig into flow-tools a bit more, I’m finding easier ways of doing things. For example, the same command line variable substitution that I’ve used to filter IP addresses with flow-nfilter can be used to generate different reports with flow-report. In /etc/flow-tools/cfg/stat.cfg the default report is: stat-report default type @{TYPE:-summary-detail} output [...]

Content Copyright Sean Walberg

More command line NetFlow reports

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Checking common port numbers on Cisco IOS

While memorizing a bunch of port numbers definitely helps you impress the ladies, not everyone has that ability. Fortunately, you can check common port numbers right on the Cisco IOS command line. Router> enable Router# conf t Router# access-list 100 permit tcp any any eq ? This will result in the following table: <0-65535> Port number bgp Border Gateway Protocol [...]

Content Copyright Sean Walberg

Checking common port numbers on Cisco IOS

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Netflow – Filtering on network and producing a report

The last article used flow-nfilter and some variable substitution to pull out all flows to a particular address. The next useful thing would be to pull out all flows to or from a particular network. To do so, we’ll have to define a new primitive that is a variable network/netmask, and then a filter specifying a [...]

Content Copyright Sean Walberg

Netflow – Filtering on network and producing a report

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Netflow – a simple filter and getting connection stats

Yesterday, we had a web site crash. I was curious if it had to do with load or something else was going on. This is a great opportunity to show how to analyze NetFlow data. First, I should mention that there may be easier ways of doing this. The flow-tools package includes a lot of [...]

Content Copyright Sean Walberg

Netflow – a simple filter and getting connection stats

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Collecting NetFlow data

In the NetFlow world, a NetFlow exporter sends flow data to a NetFlow collector. The exporter is usually a router, the collector is usually a Unix server of some sort. First, set up your router to export flow information: ip flow-cache timeout active 2 mls flow ip full mls flow ipx destination mls nde sender mls nde interface mls nde flow include [...]

Content Copyright Sean Walberg

Collecting NetFlow data

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Introduction to NetFlow

NetFlow is a technology that lets a router export information about current traffic to a collector for analysis. The analysis might be real time, such as to detect a denial of service attack, or not real time, such as to view trending information. NetFlow is concerned with flows, which are a one way session between [...]

Content Copyright Sean Walberg

Introduction to NetFlow

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Default routes

The other day I ran into some problems with a default route, which prompted a discussion with co-workers, which led me to look up the behavior of redistributing a static default route into a dynamic routing protocol. Take, for example, the following ! default route ip route 0.0.0.0 0.0.0.0 1.1.1.1 ! pick your routing protocol router [...]

Content Copyright Sean Walberg

Default routes

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I’ll be speaking at Sharkfest ‘08

(cross posted from my blog) I’m giving 2 talks on using Wireshark to expose VoIP problems at Sharkfest ‘08 (schedule). Details are sketchy, I think one of the talks is more of a hands on lab, the other is me talking. I’ve expanded on my techniques from the Linux Journal article I wrote [...]

Content Copyright Sean Walberg

I’ll be speaking at Sharkfest ‘08

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Using a 3750 to test cables

The 3750 (and it would appear, the 3560s, 4500s, and 6500s) have an integrated Time Domain Reflector which is used to test cables associated with a port. http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_25_see/command/reference/cli3.html#wp2168243 Today I was troubleshooting a problem at a newly renovated remote office with an IP phone that would power up but not boot. After swapping cables and phones, [...]

Content Copyright Sean Walberg

Using a 3750 to test cables

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