Thursday, March 30, 2006

OSI Layers Fundamentals

OSI Layers:
Transport layer:
1. Two main protocols (TCP & UDP).
TCP - Requires handshake and responses. Reliable.
UDP - Not reliable.
In a streaming environment, TCP would start of the session to be continued with UDP.

2. HASH value in torrent file.
Parity bits error detection and correction.

3. If you can ping the gateway, then Network and Data Link layer are working.

4. Session layer - if you know web programming, you should been familiar with session.
Troubleshooting.
step 1. Physical layer - Check cable, ethernet card blinking.
step 2. Ping loopback (127.x.x.x) - Checking the data link layer.
step 3. Ping DNS server, Ping gateway -

5. nslookup
C:\Documents and Settings\admin>nslookup
*** Can't find server name for address 172.16.0.1: Non-existent domain
*** Default servers are not available
Default Server: UnKnown
Address: 172.16.0.1
> set q=all
> it-sideways.com
Server: UnKnown
Address: 172.16.0.1
Non-authoritative answer:
it-sideways.com internet address = 64.202.189.170
it-sideways.com nameserver = park10.secureserver.net
it-sideways.com nameserver = park9.secureserver.net
it-sideways.com
primary name server = park9.secureserver.net
responsible mail addr = dns.jomax.net
serial = 2005062500
refresh = 28800 (8 hours)
retry = 7200 (2 hours)
expire = 604800 (7 days)
default TTL = 86400 (1 day)
it-sideways.com MX preference = 10, mail exchanger = mailstore1.secureserver.net

park10.secureserver.net internet address = 68.178.211.109
mailstore1.secureserver.net internet address = 64.202.166.11
OSI layers in details:

6. RPC (session layer) - Blaster worm attack using RPC protocol. Check out the dependencies using services.msc

7. Transport layer - 3 ways handshake.

8. Network layer - Route update packet (Router advertisement)

9. Data Link - Buffer management.
MAC address - First Three hexa identifies vendors (suppliers). This is known as the vendor code.

10. Physical Link - Signal and media.
Ethernet Networking:
1. CSMA/CD (half-duplex) is outdated.
2. Hub - generally half-duplex only.
3. Switch - Full-duplex (can be used for half-duplex)
4. Ethernet (Frame) types:
Ethernet_II
802.2 (Outdated)
SNAP (Outdated)

Cisco Three-layer model:
Design network - Rule of thumb.
1. 80% of the traffic should stay on the same network.
Unicast - one to one
multicast - one to many
broadcast - one to all (shouting)

Core layer:
1. Transfer data as fast as possible.
usually there would be two multi-layer switches for failover (backup).
2. Fault tolerance - One core switch down, you have the ability to bring it up.
Dedundancies - On standby. (RAID - hotswap)

Distribution layer:
1. Routing (inclusive of VLAN)
2. NAT
3. Redistributing of protocols (communications between protocols)

Access Layer:
1. Segmentation
Besides the OSI and Cisco three layer model,there is another model called "Avid" model.

Cabling:
1. CAT-5 (RJ 45) maximum stretch = 100 meters. (more than that will need a repeater)
2. Core layer would require Gigabit Ethernet.
3. Serial point-to-point connection.
232 cable.
DCE (Data channel equipment) - connect to ISP.
- Assign clock rate (real wire speed)
- Determines the real wire speed
DTE (Data terminal equipment)
- Assign bandwidth (not real bandwidth)

29 comments:

Scott Arthur Edwards said...

NOW, check this out for FREE...

There is a new, fully automated traffic-generation system that can send 1000's of targeted prospects to your website, for FREE! It only takes 5 minutes to set up to set your FREE account!

To find out more visit: homebusiness site. It successfully exposes FREE information covering Traffic and homebusiness related stuff.

all job search engines said...

A fantastic blog yours. Keep it up.
If you have a moment, please visit my all job search engines site.
I send you warm regards and wish you continued success.

automobile insurance calculator said...

I am here because of search results for blogs with a related topic to mine.
Please,accept my congratulations for your excellent work!
I have a automobile insurance calculator site.
Come and check it out if you get time :-)
Best regards!

automotive employers said...

A fantastic blog yours. Keep it up.
If you have a moment, please visit my automotive employers site.
I send you warm regards and wish you continued success.

automotive employers said...

A fantastic blog yours. Keep it up.
If you have a moment, please visit my automotive employers site.
I send you warm regards and wish you continued success.

automobile insurance service driver vehicle said...

Hey Fellow, you have a top-notch blog here!
If you have a moment, please have a look at my automobile insurance service driver vehicle site.
Good luck!

stock market information said...

I am here because of search results for blogs with a related topic to mine.
Please,accept my congratulations for your excellent work!
I have a stock market information site.
Come and check it out if you get time :-)
Best regards!

Wireless retail software said...

Your blog I found to be very interesting!
I just came across your blog and wanted to
drop you a note telling you how impressed I was with
the information you have posted here.
I have a Wireless retail software
site.
Come and check it out if you get time :-)
Best regards!

wine retail said...

I am here because of search results for blogs with a related topic to mine.
Please,accept my congratulations for your excellent work!
I have a wine retail site.
Come and check it out if you get time :-)
Best regards!

yahoo anti virus protection said...

Hey, you have a great blog here! I'm definitely going to bookmark you!
I have a yahoo anti virus protection site.
Come and check it out if you get time :-)
Greetings.

sed rate said...

Hi there Blogger, a real useful blog.Keep with the good work.
If you have a moment, please visit my sed rate site.
I send you warm regards and wishes of continued success.

Bill Harrison said...

I am here because of search results for blogs with a related topic to mine.
Please,accept my congratulations for your excellent work!
I have a 2012 london domain name olympics site.
Come and check it out if you get time :-)
Best regards!

Jane Carpenter said...

Hi there Blogger, a real useful blog.Keep with the good work.
If you have a moment, please visit my 101 domain names site.
I send you warm regards and wishes of continued success.

Paul Adams said...

Hi Fellow! I was just searching blogs,and I found yours! I like it!
If you have a moment, please visit my cheap hosting free domain site.
Good luck!

Scott Arthur Edwards said...

Here it is... FREE advertising, FREE download. No cost to you! Get your FREE download NOW! Make money and get FREE advertising! This is a great program for you to take advantage of... Check this out now for FREE!

To find out more visit: residual income opportunities site. It successfully exposes FREE information covering traffic and residual income opportunities related stuff. Don't forget, FREE, FREE, FREE!!!

Anonymous said...

Dear friends, Now you can help yourself take advantage of the huge surpluses of FREE advertising in your spare time, in the comfort of your own home. Hook up NOW with this exiting program. Click here: FREE INFORMATION

Anonymous said...

[url=http://drugs-pharmacy.biz/phentermine-overnight-delivery.html]phentermine overnight delivery[/url]

Anonymous said...

brutal bj

Anonymous said...

http://atalara.com/news/categ-Bookmakers_betting-55.html Bookmakers betting
Bookmakers betting

Anonymous said...

http://atalara.com/news/categ-Football_Betting_Lines-316.html Football Betting Lines
Football Betting Lines

Anonymous said...

websearchtravel.com
Cruise Tahiti
Acapulco Hotels
Accommodation Mallorca
Africa Travel
Air Tickets
Air Travel
Airline Fares
Brussels Hotels
Car rental
Europe Travel

Anonymous said...

websearchtravel.com




Grand Bahamas Hotels

Anonymous said...

http://dermo-keys.com/index1.shtml
http://dermo-keys.com/index2.shtml
http://dermo-keys.com/index3.shtml
http://dermo-keys.com/index4.shtml
http://dermo-keys.com/index5.shtml
http://dermo-keys.com/index6.shtml
http://dermo-keys.com/index7.shtml
http://dermo-keys.com/index8.shtml
http://dermo-keys.com/index9.shtml
http://dermo-keys.com/index10.shtml
http://dermo-keys.com/index11.shtml
http://dermo-keys.com/index12.shtml
http://dermo-keys.com/index13.shtml
http://dermo-keys.com/index14.shtml
http://dermo-keys.com/index15.shtml

Anonymous said...

http://roorex.net/en History of Education

http://roorex.net/reg-India-266.html India
India

Anonymous said...

http://erotic.artmam.com/ - erotic art

http://fine-art.artmam.com/ - oil painting art

http://sensual.artmam.com/ - erotic drawing


http://artmam.net/Dir-Marketing__Advertising_Publicity.htm Marketing Advertising Publicity
Marketing Advertising Publicity

Anonymous said...

I'm trying to finish college at MSU and wanted to make a couple of extra bucks. I got scammed quite a few times, but found something that actually makes me about $200 bucks a month now. I know it isn't much, but at least it is legit. You can check it out and I hope it helps you out too.
Paid Survey Program That Actually Works

Anonymous said...

Watiti.com
Join me and my circle of friends at http://www.watiti.com, an online social networking community that connects people from all over the world.

Meet new people, share photos, create or attend events, post free classifieds, send free e-cards, listen music, read blogs, upload videos, be part of a club, chat rooms, forum and much more!

See you around! Bring all your friends too!

Watiti.com

Anonymous said...

abusive relationship

Anonymous said...

Very nice site! honeywell hwm 255 humidifier Girl's going places scholarship Fioricet tablet what is fioricet neurontin withdrawal Delaware bextra attorney Julia bond anal pics mens coats What is adipex used for Diving florida school lcd monitors wellbutrin order adipex sunday january 29 article skype phone story New guinea meridia http://www.zyban-6.info Computer programmer ford diesel Fishing torrents