Network layer

Question 1

Characteristics of IP

Answer 1

1. Best effort - will not guarantee the delivery of the packet and has lower overhead as there is no mechanism to re-send data
2. Connectionless - does not establish connection with destination, if need for connection oriented traffic TCP will do it
3. Media independent - doesn’t matter what type of frame or what type of media it is. Fragmenting used to split packet into many pieces causing latency. Changes MTU based on info sent by data link layer
4. Unreliable - cannot fix undelivered packets

Question 2

IPv4 Limitations

Answer 2

1. Address depletion - not enough addresses
2. Lack of end-to-end connectivity - private addressing and NAT is needed ending direct communication with public addresses
3. Increased network complexity - NAT was meant as a temporary solution and manipulating the network address in the header will increase complexity and latency

Question 3

Ipv6 benefits **

Answer 3

1. Increased address space - now has much more addresses
2. Improved packet handling - simplified header with fewer fields
3. Depletes need for NAT - no need to use private addressing internally due to large amount of addresses

Question 4

Features of default gateway

Answer 4

1. Must have IP address in range of rest of the LAN
2. can accept data from lan and route data to other lan
3. it can route to other networks

Question 5

Static route characteristics

Answer 5

1. Route must be Manually added by admin and must be manually changed when the topology changes
2. good for small and redundant networks
3. often paired with a dynamic routing protocol for configuring default route

Question 6

Dynamic route characteristics

Answer 6

1. Discovers new remote networks
2. Always choose the best path destination
3. Update best destination based on topology change
4. Maintain up to date information
5. Share static routes to other routers

Question 6

ARP functions

Answer 6

1. Resolve IP address to corresponding mac address
2. Maintain an ARP table that has all these mappings

Question 7

How does ARP work

Answer 7

To send a frame, a device will search its ARP table for a destination IPv4 address and a
corresponding MAC address.
* If the packet’s destination IPv4 address is on the same network, the device will
search the ARP table for the destination IPv4 address.
* If the destination IPv4 address is on a different network, the device will search the
ARP table for the IPv4 address of the default gateway.
* If the device locates the IPv4 address, its corresponding MAC address is used as the
destination MAC address in the frame.
* If there is no ARP table entry is found, then the device sends an ARP request.

Question 7

How does ARP work

Answer 7

To send a frame, a device will search its ARP table for a destination IPv4 address and a
corresponding MAC address.
* If the packet’s destination IPv4 address is on the same network, the device will
search the ARP table for the destination IPv4 address.
* If the destination IPv4 address is on a different network, the device will search the
ARP table for the IPv4 address of the default gateway.
* If the device locates the IPv4 address, its corresponding MAC address is used as the
destination MAC address in the frame.
* If there is no ARP table entry is found, then the device sends an ARP request.