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Mismatch duplex settings can cause all sorts of headaches. I just had to clean some up this morning between a router and a switch. Here is a cheat sheet on which settings work or not.

	Auto Detect	Half Duplex	Full Duplex
Auto Detect	OK	OK - not optimal	NO - see note
Half Duplex	OK - not optimal	OK	NO
Full Duplex	NO - see note	NO	OK

Note: A forced duplex setting such as half or full will stop the port from sending Fast Link Pulse (FLP) or the 802.3u auto-negotiation protocol. FLP notifies the other end the auto-negotiation options of the source sending the FLP. If a port is set to auto and it does not receive FLP, the default behavior is for it to assume the other end of the connection is set to half duplex (last priority or lowest common denominator). You can now see why full/auto won't work to well. Oh, and obviously if the speed of the interfaces don't match things aren't going to work to well either. Here is the table of priority order that 802.3u uses, in case you are interested.

Auto-negotiation Process:
Priority Physical-Layer
1 100BaseT2 full duplex
2 100BaseT2 half duplex
3 100BaseTX full duplex
4 100BaseT4 half duplex*
5 100BaseTX half duplex
6 10BaseT full duplex
7 10BaseT half duplex

Note: * 100BaseT4 supports only half duplex.

- Ed

I have been looking for vendors to sponsor both the user groups that I help out. The San Francisco Network Technology Users Group and the Tri-Valley Network Users Group are both excellent user groups for those that are in the San Francisco Bay Area. They focus on Network and System Admins. If anyone is interested in sponsoring either group please send me a note via their respective websites. I would also plug the East Bay Cisco Users Group and the Southern California Cisco Users Group which are both excellent and have great folks running them.
- Ed

So far, here is what I have come up with that I think will be worthwhile.

Routing TCP/IP, Volume I (CCIE Professional Development) (Doyle, ISBN# 1578700418)
Routing TCP/IP, Volume II (CCIE Professional Development) (Doyle, DeHaven, Carroll, ISBN# 1578700892)
Cisco LAN Switching (Clark, Hamilton, ISBN# 1578700949)
Internet Routing Architectures, 2nd edition (Sam Halabi, ISBN# 15787050862)
CCIE Practical Studies Volume I (Solie, ISBN# 1587200023)
CCIE Practical Studies Volume II (CCIE Self-Study) (Solie, Lynch, ISBN# 1587050722)
Cisco Certification: Bridges, Routers and Switches for CCIEs (2nd Edition) (Caslow, Pavlichenko, ISBN# 0130903892)
CCIE Routing and Switching Exam Certification Guide (Bruno, ISBN# 1587200538)
Cisco OSPF Command and Configuration Handbook (Parkhurst, ISBN# 1587050714)
Configuring IPv6 for Cisco IOS (Edgar Parenti, Jr., Eric Knnip, Brian Browne, Syngress, ISBN# 1928994849)
Cisco BGP-4 Command and Configuration Handbook (Parkhurst, ISBN# 158705017X)
802.11 Wireless LAN Fundamentals (Pejman Roshan, Jonathan Leary, ISBN# 1587050773)
Wi-Fi (802.11) Network Habdbook (Neil P. Reid, Ron Seide, McGraw Hill Osborne Media, ISBN# 0072226234)

I am considering the CCIE Pratice Labs book from Cisco Press but haven't decided on it yet. I think I am going to use Certification Zone's website subscription for practice exam and study materials. They have good sample content posted up and seem to have a good reputation out there.
- Ed

I have started organizing my links into catagories - mainly for my own use so I don't have to keep trying to find the same vendors and tools over and over again. Google still makes it easy to find them again but sometimes you forget vendor names - you only remember the catagory! I will try and ad to it every week.
- Ed

I needed to update my Visio stencils (yet again) for some current work I am doing. There are a couple of very useful sites out there to get links to manufacture's Visio stencils for their gear and also generic ones.

Visio Cafe - ultimate site for your stencil fix!
mvps.org - a great site on Visio info
Cisco's Stencil Library - this link requires that you have a CCO login account
Dell's Library - for a manufacture supplied stencil I think they are very poor in quality
Juniper's Library - includes the NetScreen product line along with the Juniper gear

HP's wonderfully stencils can be found at the Visio Cafe link.

- Ed