CS 6250 Computer Networks Exam 2 with
correct answers
What are the main components of a router? - 🔰CORRECT
ANSWERS ✔✔-Input/Output ports
-The switching fabric
-The routing processor
What do the input ports do for a router? - 🔰CORRECT ANSWERS
✔✔-Line termination
-Data link processing unit decapsulate the packets
-Checks with the forwarding table to ensure each packet is
forwarded to the appropriate output port
What does the switching fabric do? - 🔰CORRECT ANSWERS
✔✔Moves packets from input to output ports. 3 Types: memory,
bus, and crossbar
What do the output ports do? - 🔰CORRECT ANSWERS
✔✔Receive and queue the packets that come from the switching
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,fabric and send them over to the outgoing link
Routers control plane functions - 🔰CORRECT ANSWERS
✔✔implements routing protocols, maintains the routing tables,
computers the forwarding table
Router Lookup (Task 1 of 6) - 🔰CORRECT ANSWERS ✔✔When
a packet arrives, router looks at the destination IP address and
determines the output link by looking at the forwarding table or
FIB.
Router Switching (Task 2 of 6) - 🔰CORRECT ANSWERS ✔✔After
lookup, the switching system takes over to transfer the packet from
the input link to the output link
Router Queueing (Task 3 of 6) - 🔰CORRECT ANSWERS ✔✔After
switching, it will need to be queued if the link is congested. The
queue maybe simple as FIFO or some other algorithm
Router Header validation and checksum (4 of 6) - 🔰CORRECT
ANSWERS ✔✔The router checks the packet's version number,
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, decrements the time-to-live field, and recalculates the header
checksum
Router Processing (Task 5 of 6) - 🔰CORRECT ANSWERS ✔✔The
routers build their forwarding tables using routing protocols such
as RIP, OSPF, BGP - they are implemented in the routing
processors
Protocol Processing (Task 6 of 6) - 🔰CORRECT ANSWERS
✔✔The routers, in order to implement their functions, need to
implement the following protocols:
-Simple Network Management Protocol which provides counters
for remote inspection
-TCP and UDP for remote communication with the router
-Internet Control Message Protocol for sending error messages
Switching via memory - 🔰CORRECT ANSWERS ✔✔The ports
operate as I/O devices in an operating system. When an input port
receives a packet, it sends an interrupt to the routing processor and
the packet is coped to the processors memory. Process extracts
address and looks to table to find output port. Then its copied to the
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correct answers
What are the main components of a router? - 🔰CORRECT
ANSWERS ✔✔-Input/Output ports
-The switching fabric
-The routing processor
What do the input ports do for a router? - 🔰CORRECT ANSWERS
✔✔-Line termination
-Data link processing unit decapsulate the packets
-Checks with the forwarding table to ensure each packet is
forwarded to the appropriate output port
What does the switching fabric do? - 🔰CORRECT ANSWERS
✔✔Moves packets from input to output ports. 3 Types: memory,
bus, and crossbar
What do the output ports do? - 🔰CORRECT ANSWERS
✔✔Receive and queue the packets that come from the switching
1 \\\\\\/ \\\\\\
20
,fabric and send them over to the outgoing link
Routers control plane functions - 🔰CORRECT ANSWERS
✔✔implements routing protocols, maintains the routing tables,
computers the forwarding table
Router Lookup (Task 1 of 6) - 🔰CORRECT ANSWERS ✔✔When
a packet arrives, router looks at the destination IP address and
determines the output link by looking at the forwarding table or
FIB.
Router Switching (Task 2 of 6) - 🔰CORRECT ANSWERS ✔✔After
lookup, the switching system takes over to transfer the packet from
the input link to the output link
Router Queueing (Task 3 of 6) - 🔰CORRECT ANSWERS ✔✔After
switching, it will need to be queued if the link is congested. The
queue maybe simple as FIFO or some other algorithm
Router Header validation and checksum (4 of 6) - 🔰CORRECT
ANSWERS ✔✔The router checks the packet's version number,
2 \\\\\\/ \\\\\\
20
, decrements the time-to-live field, and recalculates the header
checksum
Router Processing (Task 5 of 6) - 🔰CORRECT ANSWERS ✔✔The
routers build their forwarding tables using routing protocols such
as RIP, OSPF, BGP - they are implemented in the routing
processors
Protocol Processing (Task 6 of 6) - 🔰CORRECT ANSWERS
✔✔The routers, in order to implement their functions, need to
implement the following protocols:
-Simple Network Management Protocol which provides counters
for remote inspection
-TCP and UDP for remote communication with the router
-Internet Control Message Protocol for sending error messages
Switching via memory - 🔰CORRECT ANSWERS ✔✔The ports
operate as I/O devices in an operating system. When an input port
receives a packet, it sends an interrupt to the routing processor and
the packet is coped to the processors memory. Process extracts
address and looks to table to find output port. Then its copied to the
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20
