To set up netflow on a Cisco router (in our case a Cisco 3750 with IOS 12.2) we need to tell it where to send the netflow data to. In the example below the destination (172.17.1.1) should have a netflow listener or capture running on udp port 9696.

• Router#enable
• Router#configure terminal
• Router(config)#ip flow-export
  
• Router(config-if)#version 5
• Router(config)#ip flow-export destination 172.17.1.1 9696

Next we have to set up each interface for which we want the netflow data from. In the case where the interface is not part of a defined VLAN

• Router(config)#interface GigabitEthernet1/0/1
• Router(config-if)#ip route-cache flow
• Router(config-if)#ip flow ingress

In the case of VLANs and trunking the set up is slightly different (just to confuse myself I put in all the gory details). First we define the interface/port that we are interested in.

• Router(config-if)#interface GigabitEthernet1/0/2
• Router(config-if)# description a VLANed interface
• Router(config-if)# switchport access vlan 2
• Router(config-if)# switchport trunk encapsulation dot1q
• Router(config-if)# switchport trunk native vlan 2
• Router(config-if)# switchport mode trunk
• Router(config-if)# speed 1000
• Router(config-if)# duplex full

Then we define the VLAN interface

• Router(config-if)#interface Vlan2
• Router(config-if)# description a VLAN for our interface
• Router(config-if)# ip address 172.17.1.2 255.255.255.0
• Router(config-if)# ip flow ingress
• Router(config-if)# ip route-cache flow
  

Exit from the configure mode and then do:

• Router(config-if)#show ip flow export

You should get something like:

Flow export v5 is enabled for main cache
Exporting flows to 172.17.1.1 (6969)
Exporting using source IP address 172.17.1..249
Version 5 flow records
853478 flows exported in 66526 udp datagrams
0 flows failed due to lack of export packet
0 export packets were sent up to process level

Other useful commands are:

• Router(config-if)#show ip flow interface
• Router(config-if)#show ip cache flow

NMS Inventory - for quite a while I have been meaning to document an NMS (Network Management System) which is currently running at a clients site.

The base operating system is currently FreeBSD 6.1 with a whole lot of useful tools as well as SMS alerting system. The base install includes Apache 1.3 (good old reliable stuff!), MySQL 5.1, Perl and PHP.

In the following pages I will attempt to describe several of the packages which I find very useful, such as:
- cacti
- NeDi (Network Discovery tools)
- netflow tools

.....

Hard drive miniaturization technology wins physics Nobel

Albert Fert and Peter Gruenberg won the 2007 Nobel Prize for physics for discoveries allowing the miniaturization of hard disks in electronic devices.

I must admit I have never ever given a second thought about what format I used on my USB flash drive, that is until I spotted the following article at IronGeek website entitled: File Systems and thumb drives: Choosing between FAT16, FAT32 and NTFS to get a faster USB Flash Drive . Fascinating stuff (really!) and just something I had never thought to try out.

Here's a link to an interesting article I spotted on the ComputerWorld website entitled "Does testing still matter?"

It's expensive and time consuming for IT managers to conduct extensive product evaluations. But columnist Craig Mathias argues that tests are still essential, particularly when it comes to wireless networking.

Link to full article

Yes, testing, despite the costs still matters!