BGP – aggregate-address

To advertise a summary route in BGP, aggregate-address is used. 

Example

The topology is:

R1 --- FR --- R2

BEFORE summarize the route:

R1 – show ip bgp

R2 – show ip bgp

To summarize the 2.x.x.x network, aggregate-address is used.

R2(config)# router bgp 200

R2(config-router)# aggregate-address 2.2.0.0 255.255.252.0

R1 – show ip bgp

R2 –show ip bgp

A summary route

*> 2.2.0.0/22       0.0.0.0                            32768 i

is advertised to R1.

Note that by default the aggregate AND ALL the specific routes are advertised.  If you want to suppress the specific routes, use the “summary-only” argument.

R2(config-router)#aggregate-address 2.2.0.0 255.255.252.0 summary-only

R1 – show ip bgp

 

R2 – show ip bgp

Notice that the specific routes are suppressed, only the summarized routes are advertised to the neighbors.

2 attributes are displayed: aggregator and atomic aggregate.

The aggregator attribute identifies the router that performed the aggregation.  In this case it is 2.2.3.2.

The atomic-aggregate attribute tells us that some information is lost because of aggregate.

My CCIE Lab Countdown

After postponing my R&S lab test several times for lots of reasons (or excuses precisely), finally confirmed 18 Sep in Tokyo for my first attempt.

84 days ta go....

Toggling rdesktop full screen mode

To rdesktop your Windows host is easy:

rdesktop -f

but the next question is, how to get back to your original Linux host?

The answer is:

Ctrl-Alt-Enter

Use it to toggle between full-screen and non-full screen mode!

Other posts on rdesktop:
http://pandaeatsbamboo.blogspot.com/2008/03/share-clipboard-and-map-network-drive.html
http://pandaeatsbamboo.blogspot.com/2008/02/remote-desktop-from-linux-rdesktop.html

iPhone 3G makes its debut

Connect to a WPA-PSK wireless network on Slax

My environment: IBM Thinkpad T60 Centrino + SLAX 6.0.7 on my USB flash disk

Slax is a very lightweight and portable linux OS and I have just tried it on my USB flash disk, it is so easy to use that I can build it from stretch and connect to my home wifi within half an hour. Here is a short tutorial in how to connect it to my WPA-PSK protected wireless network.

1. Get your Slax here:
http://www.slax.org/get_slax.php

You can either burn it on your CD or download and extract the tarball to your USB flash disk. Run the bootinst.bat or bootinst.sh to make it bootable.

2. Download wpa_supplicant from http://www.slax.org/modules.php?action=detail&id=533. Move this module into /mnt/sdb1/modules, where sdb1 is the USB flash disk in my case.

3. Create the wpa_supplicant.conf config file in /mnt/sdb1/rootcopy/etc. Here is an example:

ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0
eapol_version=1
#ap_scan=0
#fast_reauth=1

network={
ssid="pandassid"
key_mgmt=WPA-PSK
proto=WPA
pairwise=TKIP
group=TKIP
psk="ilovethisblog"
}

4. Reboot it and then run this in your terminal:
wpa_supplicant -d -iwlan0 -c/etc/wpa_supplicant.conf -Dwext

5. You should receive confirmation on the terminal saying your key is accepted. Open another terminal and run the following:

iwconfig wlan0 essid pandassid
dhcpcd -G 192.168.1.0 wlan0

6. Done!!