Citrix System Inc Interview Question
Quality Assurance EngineersTeam: Xen-Client
Country: India
Interview Type: In-Person
a packet traverses from source to destination via n routers. the value of n may vary from 0 to hop limit. the value will be 0 when the two nodes are neighbours or in short directly connected via a switch or hub, i.e. are in the same network.
When a packet is sent source to destination, it contains higher layer application data, transport layer data, IP header that mainly contains source and destination address.
the next layer is link layer that contains link layer address(in IPv6) and mac address (in Ipv4).
now the packet will contain the link layer address of next hop to be reached. If its a direct neighbour means 0 routers in between, it will have the link layer address of the destination itself, otherwise it will have the link layer address of next hop.
The link layer address is found using ARP resolution in IPv4 and neighbour dscovery protocol in IPv6
Starting from application layer....your message will be kept in a packet containing header with port address (Source Port no, Destination Port no),in Transport layer then that packet will be transferred to network layer in with another header is added with IP addresses (Source IP, destination IP), and then this packet is transferred to data link layer....in which a header and a tailor is added..header is containing the Souce MAC addess and the MAC address of the next router to which it is to be forwarded.....(The MAC address of the next router is obtained by ARP...)....and then at the router we are having three layers....Data Link layer, Network layer and then transport layer....at the routers...the Destination MAC address is canged...which is of next...router fund by ARP.......and at last when the Destinations is reached,,,,,the data will be passed though the 5 layes from bottom to top...removing the headers one by one....and the will be shown according to the port no specified.......like 80 is the port no for http......
- Nitesh Kumar (MADE EASY) July 21, 2012