An ISP has CIDR block 135.102.192.0/21. The ISP wants to create 4 sub-blocks of equal size from this block.

How many bits should the ISP add to the mask for the subblocks?

What are the network addresses (in dotted decimal with the mask in slash notation) for each subblock?

What is the maximum number of hosts in each subblock?

An ISP has CIDR block 204.15.176.0/16. The ISP needs to allocate the following subblocks:

2 subblocks of 200 addresses

1 subblock of 100 addresses

Design the subblocks (showing the mask and the first and last addresses in each subblock) using variable length subnet masks. [Assume the address blocks include addresses where the host ids are all zeros and all ones.]

Design subnets meet the following requirements:

The available IP address space is the range 10.10.172.0-10.10.172.255. You may only assign IP addresses in this range.

The LAN connected to router A must be able to support at least 50 hosts.

The LAN connected to router B must be able to support at least 75 hosts.

The LAN connected to router C must be able to support at least 20 hosts.

Design the subnets (showing the mask and the first and last addresses in each subnet) using variable length subnet masks. [Assume the address blocks include addresses where the host ids are all zeros and all ones.]

Answer the following questions concerning the IPv4 and IPv6 protocols:

4.1 A TCP segment is encapsulated in an IPv4 packet and the IPv4 packet is encapsulated

in a (non-IEEE format) Ethernet frame. Which is correct?

The type field in the Ethernet Header is a code representing TCP and the protocol field in the IP Header is a code representing Ethernet

The type field in the Ethernet Header is a code representing IP and the protocol

field in the IP Header is a code representing TCP

The type field in the Ethernet Header is a code representing Ethernet and the

protocol field in the IP Header is a code representing IP

The type field in the Ethernet Header is a code representing IP and the protocol

field in the IP Header is a code representing Ethernet

4.2 An IPv6 datagram consists of the following (in the stated order): Base Header, Routing Header, TCP Segment. What will be the Next Header field of the Base Header?

a. Fragmentation Header b. Authentication Header

c. TCP d. Routing Header

4.3 Why is fragmentation of an IP packet sometimes required?

Because an IP packet can hold more data than a frame

Because networks can be subnetted

Because IP is a connectionless protocol

Because different applications send different amounts of data

4.4 An IPv4 fragment has an offset that is greater than 0 and MF = 1. This is

a. the first fragment b. a middle fragment

c. the last fragment d. cannot be determined

4.5 What is one difference between fragmentation in IPv4 and IPv6?

a. There are no differences fragmentation is identical in both versions of IP

b. IPv6 permits fragmentation by the source or intermediate routers, but IPv4 allows

only fragmentation by the source

c. IPv6 fragmentation information is in an extension header and IPv4 fragmentation

information is in the regular header

d. Both (b) and (c)

4.6 What is the purpose of the Time to Live field in the IPv4 header?

It indicates the quality of service requirements

It indicates the number of bytes in the header

It indicates whether the packet is a fragment or not

It detects lost packets

An IP packet has 1200 bytes of payload data and a 28 byte header.

What values will be in the HLEN (also called IHL) field in the header?

What value will be in the Total Length field in the header?

Answer the following questions concerning IPv6 addresses:

Show the shortest form of 0:0B0E:0000:0000:0000:0000:0000:12DF by removing leading zeros and using ::

Expand A2:34::67E to its unabbreviated form. You do not need to include leading zeros.

An IPv6 packet contains the base header, one 20 byte extension header, and 1000 bytes of payload data.

What is in the payload length field?

How many total bytes are in the packet?

A large IPv4 datagram carrying 1500 bytes of payload data is fragmented to pass over a network where the MTU is 660 bytes. Assume the IP header is 20 bytes in each fragment and assume the identification of the original datagram is 12345. For each fragment, show the contents of the Identification field, the Offset field, the Total Length field, and the More Fragments flag in the IP header.

An IPv6 packet has a 40 byte base header, a 16 byte destination options extension header (which is not used for routing) and 1000 bytes of payload data. This is to be fragmented to travel over a network with a MTU of 600 bytes. Considering the fragmentable and unfragmentable parts of this packet, create a sketch showing the headers and data in each fragment, including the number of bytes. Dont forget the fragmentation header, which is 8 bytes.

Use the Wireshark trace (http-ethereal-trace-1) provided on Moodle to answer the questions below:

For ease of use, the header length field contains the actual bytes in the header, rather than bytes/4 as it is actually sent.

Examine the IP header of packet 10, which carries an HTTP (web page) request message.

What is the source IP address?

What is the destination IP address?

What are the header length and total length fields?

From the data in step (iii) above, calculate the number of bytes of payload data in this packet.

Recall that the protocol field in the IP header identifies the type of data carried by the IP packet. What kind of data does this packet carry?