Cisco IOS DHCP Static Reservations

I recently wanted to configure an HP Jetdirect print server to receive an IP address via DHCP with the server configured to hand out a static reservation. I had used the IOS DHCP pool sub-command of “client-identifier” in the past to create static reservations for Cisco IP phones and various Windows and MAC OS desktops. When I user the familiar syntax of a client-identifier formatted as 01xx.xxxx.xxxx.xx where the leading 01 indicates the Ethernet media type.

This technique has worked well for me in the past for most network devices, but it refused to assign the address I wanted to this HP Jetdirect. I did some research and found that another way to assign DHCP addresses based on MAC addresses is to use the DHCP pool sub-configuration parameter of “hardware-address xxxx.xxxx.xxxx” where the xxxx.xxxx.xxxx is the full MAC address without any prefix like we used above.

The working configuration looked like this:

ip dhcp pool HPJETDIRECT
   hardware-address 0011.0aed.62b6

The working configuration for my laptop looks like this (notice the leading 01 on the client-identifier followed by my MAC address):

   client-identifier 0134.159e.90de.3b

D-Link DSL-2750U Router

I recently helped a family member upgrade a combination DSL modem/WiFi router and found that in Kuching, Malaysia the best option available was a D-Link DSL-2750U which is a rather new product. It is a pretty generic ADSL router with 802.11n WiFi that also has a 4 port 10/100 Mbps switch and a single USB port. The USB port can connect to a printer, storage device, or a 3G adapter. After installing the router I was pleasantly surprised by the DSL setup wizard which asked for my location and my service provider. After this I was prompted for the PPPoE username and password. Once this process completed everything seemed to work correctly.

After using the internet for a few hours I noticed that it seemed to slow down quite a bit whenever anyone accessed the internet (wired or wireless). If I ran a continuous ping from a computer on the LAN to the router’s IP I saw a HUGE increase in latency from less than 1 msec to over 1,000 msec. If I connected via SSH to the command line interface and ran the “sysinfo” command the loadavg was spiking up to more than 20.

After trying to adjust nearly every setting I could think of I finally upgraded the firmware to version 1.01 (it shipped with 1.00) and everything started working WAY better. The latency no longer changes more than a few milliseconds when users access the internet and the loadavg stays below 1.

Outside of that issue I’m quite pleased with the device and would recommend it to anyone looking for an entry level all-in-one home router.

Open Source System and Network Management Software

This is mostly notes for myself… however, it was a useful post on NANOG that I wanted to keep track of. So I’m listing some packages to manage systems and devices via SNMP, syslog, daemons on the hosts, etc… and of course including graphing of time series data and such too.

Argus –
BigBrother –
Cacti –
Groundwork –
Hyperic –
Munin –
Nagios –
OpenNMS –
OpManager –
opsview –
Orion (not open source) –
osimius –
PandoraFMS –
Spiceworks –
Zabbix –
Zenoss –

NMIS – – – a fork of Nagios – another netflow tool – amazing network discovery and inventory of hardware/network resources – audit tool for different network devices