Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

OSI layers working

Hi ,

If i  ping ,how it works while connecting yahoomail.

Can you please expalin in OSI model in step by step

Thanks in advance


New Member

OSI layers working

Actually ICMP is a protocol from Layer 3, it would not use all layers as you want. To have a full detailed connection you would need to use a service like a HTTP connection:

- Layer 7 application - HTTP - Exchange the messages
     Client would send out HTTP header
     Server answers: HTTP header [File]
     Server keeps sending File


Layer 6 - Takes care of compression and encryption 
- Layer 5 - Keeps the session supporting upper layer


- Layer 4 - Will add a header with source and destination ports, and the PDU name is Segment. On this case it will use as destination port 80 and source would be a ramdom port upper 1063.
HTTP uses port 80 of TCP, then, all TCP features such for ack, sequence number and windowing

(4-Source P / Dsti P.)[Data]

- Layer 3 - This layer will add its header which contains source (requestor) and destination (HTTP server) address. Now it becomes a packet

(3-Source IP / Desti IP) [(4-Source P / Dsti P.)[Data]]

- Layer 2 - Will address it header as well and a trailer for FCS (Frame check sequence). It depends the king of technology?
Ethernet - Header is source and destination (next-hop, like default-gateway) MAC address; OR
Frame-relay - Header contains DLCI
Now the PDU is frame

(2-Source MAC / Desti MAC) (3-Source IP / Desti IP) [(4-Source P / Dsti P.)[Data]](2-FCS)]

- Layer 1 is the medium, the frame is going to be converted into bits/eletronic waves and send out on the cables.

Bits (0010010101001001001001010100101010010101010)

As soon those bits arrived on the next point, it will check until its layer, like:
A switch will check until layer 2
A router will until layer 3
And destination server will go UP, checking 4, 5, 6 and 7



* Pls rate every valid post

New Member

OSI layers working

Thanks for respone

If you ping the google site from Command prompt how it will works

CreatePlease to create content