Juniper Networks Interview Question
Presentation, Layer 6 : This layer provides independence
from differences in data representation (e.g., encryption)
by translating from application to network format, and vice
versa. The presentation layer works to transform data into
the form that the application layer can accept. This layer
formats and encrypts data to be sent across a network,
providing freedom from compatibility problems. It is
sometimes called the syntax layer.
I was asked a similar question by Juniper.There are three routers R1, R2 and R3. R1 is the router you are connected to. R3 is connected to the server which hosts yahoo.com. What will happen in each layer of TCP/IP model
Any unicast packet flowing from node to node should have 2 things
1. Ip address
2. Mac address
How these are used for below scenario:
From R1 to R3:
Ip address of yahoo.com is obtained using dnsresolution,
In L3 R1 will know that there is no direct route to yahoo.com so send packet
Out with dst ipaddress of Yahoo com and with Mac address of R2(router that
Is listed in R1 routing table with shortest distance),
R2 recvs packet and sees that packet is destined to yahoo.com and
Replaces dst Mac address with next hop router Mac address and sends packet..
This is just example, if R3 is listed in R1 route then pckt will contains R3 Mac as dst Mac.
Please reply if anyone thinks otherwise.
All (7)layers co-ordinate to gether open the link we provided. if all layers have connected properly.
Application, Layer 7 : This layer supports application and
- Raj Naik June 26, 2012end-user processes. Communication partners are identified,
quality of service is identified, user authentication and
privacy are considered, and any constraints on data syntax
are identified. Everything at this layer is application-
specific. This layer provides application services for file
transfers, e-mail, and other network software services.
Telnet and FTP are applications that exist entirely in the
application level. Tiered application architectures are
part of this layer.
Application, Layer 7 : This layer supports application and
end-user processes. Communication partners are identified,
quality of service is identified, user authentication and
privacy are considered, and any constraints on data syntax
are identified. Everything at this layer is application-
specific. This layer provides application services for file
transfers, e-mail, and other network software services.
Telnet and FTP are applications that exist entirely in the
application level. Tiered application architectures are
part of this layer.
Session, Layer 5 : This layer establishes, manages and
terminates connections between applications. The session
layer sets up, coordinates, and terminates conversations,
exchanges, and dialogues between the applications at each
end. It deals with session and connection coordination.
Transport, Layer 4 : This layer provides transparent
transfer of data between end systems, or hosts, and is
responsible for end-to-end error recovery and flow control.
It ensures complete data transfer.
Network, Layer 3 : This layer provides switching and
routing technologies, creating logical paths, known as
virtual circuits, for transmitting data from node to node.
Routing and forwarding are functions of this layer, as well
as addressing, internetworking, error handling, congestion
control and packet sequencing.
Data Link, Layer 2 : At this layer, data packets are
encoded and decoded into bits. It furnishes transmission
protocol knowledge and management and handles errors in the
physical layer, flow control and frame synchronization. The
data link layer is divided into two sublayers: The Media
Access Control (MAC) layer and the Logical Link Control
(LLC) layer. The MAC sublayer controls how a computer on
the network gains access to the data and permission to
transmit it. The LLC layer controls frame synchronization,
flow control and error checking.
Physical, Layer 1 : This layer conveys the bit stream -
electrical impulse, light or radio signal -- through the
network at the electrical and mechanical level. It provides
the hardware means of sending and receiving data on a
carrier, including defining cables, cards and physical
aspects. Fast Ethernet, RS232, and ATM are protocols with
physical layer components.