CCIE Candidate

06/02/2007 - 2.5 hours. Take another written sample test from NetMasterClass. Scored 86%.
06/04/2007 - 2.5 hours. Write about 2/3rds of Chapter 21 posts.

adjacent layer interaction - on one computer, this is one layer providng information to the next higher layer. Software performing a higher function will request that a lower function perform a task.
boot field - the lower-order 4 bits of the configuration register. They tell the router what to load. 0×0=ROMMON, 0×1=RXBOOT, or [...]

This last post for the day is a list of keystrokes you can use at an IOS CLI to assist you. I knew all of these except for a few of the “Ctrl” commands towards the end of the list. I use them all the time, and if you’re reading this, probably you [...]

Router Boot Process

Router performs a power-on self test (POST).
Router loads and runs bootstrap code from ROM.
Router finds IOS software (or other software) and loads it. Options are:

Full-featured IOS, stored in flash. This is the binary you run for the router to run normally.

Okay - last “official” chapter of the OECG, although I still have to do the MPLS appendix. This is only 11 pages long. At a glance, we’ve all seen this material before. The 7 layers of the OSI model, how TCP/IP maps to it, plus odds and ends in router-land. Having [...]

Cisco SWAN - Structured Wireless-Aware Network - integrating wired and wireless LANs using Cisco products.
Cisco WDS - Wireless Domain Services - IOS software features that enchance and simplify wireless LAN user mobility, security, deployment and management.
client tracking - recording client assocation and roaming events so that the WLSE can monitor.

This last section of the chapter describes 3 common wireless deployment scenarios, and highlights important points to ponder about each.
Enterprise Wireless LANs

Deployed for convenient access to company data resources.
Security is, of course, a major concern.  Layer 2 security should be the focus for enterprise wireless LANs.

The CiscoWorks Wireless LAN Solution Engine is a network management platform for Cisco Aironet products. You have to have it to run a Cisco “SWAN” network. The features of WLSE follow.
Automatic Access Point Configuration

WLSE auto-discovers and configures Aironet APs. This is configurable by type of AP, subnet and software version.

This is essentially the product list from the book.  No doubt it’s a little stale.  Update Cisco wireless product information is here.  I just did a glance at it, and for the APs at least, the books still pretty close.  I’m going to include all the book info here, leaving it up to your (and [...]

It’s early on a Saturday morning, and I’m at work supporting system maintenance going on at one of our data centers.  I didn’t get too much sleep last night, because I was helping to fix a problem I’d spotted and instructed a sysadmin to preemptively fix a couple of weeks ago.  You know, BEFORE it [...]

802.11a - wireless LAN specification.  Up to 54Mbps using OFDM in the 5GHz band.
802.11b - wireless LAN specification.  Up to 11Mbps using DSSS in the 2.4GHz band.
802.11g - wireless LAN specification.  Up to 54Mbps using OFDM in the 2.4GHz band.  Backwards compatible with 802.11b.

The budding CCIE needs to understand the magic of radio waves to properly deploy wireless LANs.  Any people studying for their ham radio license “back in the day” will be familiar with much of this information.
Modulation

RF signals are analog, not digital.

Since your data is naked in the air for anyone with an antenna to see, security is particularly important in a wireless LAN.
Wired Equivalent Privacy (WEP)

WEP uses a common key to encrypt and decrypt data frames.

The book outlines here a number of common elements that need to be set on the AP, the radio card, or both.
Service Set Identifier (SSID)

An alphameric value on APs and radio cards that distinguish a wireless LAN.  It is the wireless LAN’s name.
All APs intended to participate in the same wireless LAN should have the [...]

Infrastructure Mode Operation - the most common mode in use today. Infrastructure mode has these common elements:

Scanning - radio cards perform scanning to find APs.  Scanning is used to first discover an AP, and then happens from time to time thereafter to support roaming.  802.11 defines both passive and active scanning.