Ideal body weight

Body Mass Index = Weight / (height in meter * height in meter)

Enter height in centimeter: Enter weight in kilograms: Press the calculate button to see your ideal weight:

Your ideal weight in kg:
Lowest healthy weight in kg:
Highest healthy weight in kg:
Weight loss to get to healthy (kg):

Reference:
http://www.wdxcyber.com/bmi.htm

online FM radio

download Winamp playlist for some Malayalam FM radios from here.

Reference:
http://www.shoutcast.com/Internet-Radio/malayalam
http://andomedia.custhelp.com/app/answers/detail/a_id/47

802.11 channels

UNII - Unlicensed National Information Infrastructure
DFS - Dynamic Frequency Selection
TPC - Transmitter Power Control

5GHz radio devices should follow 802.11h specification - DFS and TPC

UNII2 - (52, 56, 60, 64 ==> 5250MHz - 5350MHz)
UNII2 Ext - (100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140 ==> 5470MHz - 5725MHz)

FCC Rule requires that products operating in the UNII-2 and UNII-2 extended bands must support Dynamic Frequency Selection (DFS), to detect and automatically adjusts channels to protect WLAN communications from interfering with military or weather radar systems.



Reference:
http://en.wikipedia.org/wiki/List_of_WLAN_channels
http://www.intel.com/support/wireless/sb/CS-025343.htm
white_paper_80211n_design_and_deployment_guidelines.html
Cisco - FCC Regulations Update
wiki - ETSI

3d

Avatar is being released in Digital 3d, so there are no colored lenses to wear. ;-)





Reference:
http://answers.yahoo.com/question/index?qid=20091214025502AAKohsd

radix tree

PATRICIA - "Practical Algorithm To Retrieve Information Coded In Alphanumeric"
Radix Tree gives fastest possible ways to search prefixes.
With radix tree every internal node has at least two children.

radix trees are useful:
1. for constructing associative arrays with keys expressed as strings.
2. in the area of IP routing.
3. inverted indexes of text documents in information retrieval.
4. to map between real and virtual IRQ numbers.
5. in the memory management code, to quickly find pages which are dirty.



reference:
http://en.wikipedia.org/wiki/Radix_tree
http://lwn.net/Articles/175432
http://code.google.com/p/radixtree

multicast in detail

Internet Group Management Protocol (IGMP).

Multicast receiver inform the network that they are interested in receiving packets sent to that group. Hence a multicast distribution tree is constructed at the switch.



IGMP snooping takes place internally on L2 switch and its an optional feature for IGMP. It prevents the hosts from receiving unnecessary multicast traffic (DOS attack).

With IGMP snooping enabled,
-> when a switch hears an IGMP report / Join group from a host the switch adds the host's port number to the multicast list.
-> when the switch hears an IGMP report / Leave group, it removes the host's port from the table entry.

Reference:
IGMPv3 report packet - pcap
http://en.wikipedia.org/wiki/Multicast
http://en.wikipedia.org/wiki/IGMP
http://en.wikipedia.org/wiki/IGMP_snooping
http://www-net.cs.umass.edu/kurose/network/mcast/mcast.htm

video streaming using VLC

I have used "VLC media player 1.0.3 Goldeneye".

ON THE SERVER SIDE


-> Select "Media -> Streaming"


-> Add video file and press Stream


-> Select Next


-> Select "Display localy"
-> Select New destination as "UDP"
-> Select "Add"


-> give Address as "230.1.2.3"
-> address can be in between 224.0.0.0 - 239.255.255.255
-> And default port 1234



ON THE CLIENT SIDE


-> Select "Media -> Open Network Stream"


-> Give Protocol as "UDP"
-> Give Address as "230.1.2.3"
-> Give default port "1234"

Reference:
http://www.engadget.com/2005/11/29/how-to-stream-almost-anything-using-vlc

"ip forward-protocol udp ..." why???

IP Address: 192.168.30.201
Subnet mask: 255.255.240.0

Broadcast Address: BA = (IP) | ~(SM)

192.168.30.201 |
0.0.15.255
--------------
192.168.31.255

Broadcast Address: 192.168.31.255

Broadcast - A transmission to all interface cards on the network.
* Limited Broadcast - Sent to all NICs on the some network segment as the source NIC. It is represented with the 255.255.255.255 TCP/IP address. This broadcast is not forwarded by routers so will only appear on one network segment.
* Direct broadcast - Sent to all hosts on a network. Routers may be configured to forward directed broadcasts on large networks. For network 192.168.31.0, the broadcast is 192.168.31.255.

It selectively forward limited UDP broadcasts received on an IP interface to a configured IP address.
The default ports forwarded are:

• Time service (port 37)
• TACACS service (port 49)
• Domain Naming System (port 53)
• Trivial File Transfer Protocol (TFTP) (port 69)
• NetBIOS Name Server (port 137)
• NetBIOS Datagram Server (port 138)

Reference:
Cisco IOS IP command referance - "ip forward-protocol"
http://www.comptechdoc.org/independent/networking/guide/netbroadcasting.html