networking publications

These were listed on the Cisco website as being good resources:
(but they actually mostly suck)

# Networking Professionals Connection
# Cisco IT@Work
# Blogs@Cisco
# Networkers Online
# The Internet Protocol Journal
# Cisco Technical Services Newsletter
# Technical Support and Documentation
# Learning and Events
# Google Groups: comp.dcom.sys.cisco
# Cisco Learning Connection
# Cisco Certifications Community

Cisco 871 wireless router - part 2

Finally!!! I can get out to Internet wirelessly thru my 871w. It took lots of reading and troubleshooting, but it's working. I had to break down and call for help, so I can't take credit for this myself. Vivek, my Indian guru, solved it for me. I did not have the following 2 lines in my config:

bridge 1 protocol ieee
bridge 1 route ip

The first line establishes the "ieee" type spanning tree protocol for bridge group 1, and , I assume, establishes bridge group 1 in the first place. The second line tells the router to route IP on any interface that has an IP address, even though the interface is in a bridge group.

Without the "bridge 1 route IP" command, then IP ain't routed, it's bridged. To bridge is to forward a packet using layer 2 addressing info (MAC address) instead of layer 3 addressing info (IP address). But it wasn't working, so maybe it wasn't bridging either????????

After I entered that command in my 871 config, The computers connected wirelessly immediately got IP addresses from the dhcp server on the 871 and started being able to talk to Internet.

The BVI interface is something that is new to me. Apparently it is like a group IP mailbox for all the interfaces that don't have IP addresses. In other words, all of the interfaces that are attached to the "switch" portion of the 871 rather than the router portion. Here's the deal: If the 871 were just a plain router with no "virtual switch" built in, then of course it would have an interface with an IP address which was connected by ethernet cable to a physical switch. All the computers would in turn be connected to the switch.

Since that interface to the physical switch does't exist when the switch is built in, the interface is created out of thin air and called a BVI (bridge virtual interface). At lease that's my understanding........

Here are some good commands I learned:

show ip dhcp bindings - a good troubleshooting command that shows what addresses the router's dhcp server has handed out to which MAC addresses


show dot11 associations - also good for troubleshooting. It shows which computers are communicating with the wireless network.

show ip dhcp import - shows what data (dns server addresses, domain name, etc) is being sent to dhcp clients by the dhcp server.

871w - further info

show arp is a good way to see MAC addresses of the router's interfaces and the MAC addresses of the devices that the router is connected to


sailboat#show arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 75.66.88.84 - 001b.90c9.a9ea ARPA FastEthernet4
Internet 10.10.10.2 13 0015.c5ae.b814 ARPA Vlan1
Internet 10.10.10.3 2 0017.3181.d278 ARPA Vlan1
Internet 10.10.10.1 - 001b.90c9.a9e0 ARPA Vlan1
Internet 75.66.88.1 0 0030.b8cb.5e11 ARPA FastEthernet4

copy flash tftp
This is the command to use to copy the current IOS image to whatever tftp server you are using.

show file systems - shows the various places (directories) on a cisco router where files are stored

cd nvram: - this changes the current directory to the nvram directory. To get back to flash, which is apparently the home directory, just type cd by itself

dir - just like DOS! - shows listing of files in the current directory

pwd - just like Linux! - shows what the present working directory is

show file information flash:c870-advsecurityk9-mz.124-4.T7.bin - this gives some info about the file named c870-advsecurityk9-mz.124-4.T7.bin in the flash: directory

delete slot0:myconfig - this erases the file named myconfig in slot0:

Erasing flash memory

In order to reclaim any space taken up by files in Flash memory, you must erase the entire file system using the erase flash: or erase bootflash: EXEC command. These commands reclaim all of the space in Flash memory, erasing all files, deleted or not, in the process. Once erased, these files cannot be recovered. Before erasing Flash memory, save any files you want to keep in another location (an FTP server, for example). Copy the files back to Flash memory after you have erased the device.

This info comes from http://www.cisco.com/univercd/cc
/td/doc/product
/software/ios122/122cgcr
/ffun_c/ffcprt2/fcf006.htm#wp1000939

Retrospect Express HD

I just installed Retrospect Express HD on my computer and gave it a try. It works great! It is uncomplicated and has a slick interface. Even though I use Mozypro for my main backup method, I like having a backup of my backup. Of course, retrospect only backed my data up to the LaCie Ethernet disk mini on my LAN, so if there is a fire, it might take out both my computer and the LaCie (they are both in the same room). So Mozy Pro still wins because data is backed up off site.

At some point I will try to map a drive letter to a drive at the NBC office and see if Retrospect can back up over the Internet.

PC World gave Retrospect Express HD a good rating, but recommended that readers look at NTI's $25 Shadow and IBM's $35 CDP also. I will do so.