Suppose a message of size 15000 bytes is transmitted from a source to a destination using IPv4 protocol via two routers as shown in the figure. Each router has a defined maximum transmission unit (MTU) as shown in the figure, including IP header. The number of fragments that will be delivered to the destination is ________ . (Answer in integer)
The original message size is 15000 bytes. Using the IPv4 protocol, fragmentation occurs as follows:
- Router-1 has an MTU of 5000 bytes. Subtracting 20 bytes for the IP header, the maximum data size per fragment is 4980 bytes.
- The message is split into three fragments:
- First: 4980 bytes
- Second: 4980 bytes
- Third: 5040 bytes (remaining 4980 bytes + 20 bytes for header)
- Router-2 has an MTU of 3000 bytes. Subtracting 20 bytes for the header, the maximum data size is 2980 bytes.
- Re-fragment these:
- First fragment becomes two: 2980 and 2020 bytes
- Second becomes two: 2980 and 2020 bytes
- Third becomes two: 2980 and 2060 bytes
Total fragments delivered: 7 (as expected within the range 7,7).
Important Questions from IPv4
An organization is granted the block 130.56.0.0/16. The administrator wants to create 1024 subnets. Find first and last addresses of last subnet.
1.
130.56.0.0
130.56.254.255
2.
130.56.255.0
130.56.255.255
3.
130.56.0.192
130.255.255.255
4.
130.56.255.192
130.56.255.255
An organization is granted the block 130.56.0.0/16. The administrator wants to create 1024 subnets. Find the subnet prefix.
An organization is granted the block 130.56.0.0/16. The administrator wants to create 1024 subnets.
Find first and last addresses of First subnet.
1.
130.56.0.0
130.56.254.254
2.
130.56.0.0
130.56.0.63
3.
130.0.0.0
130.255.255.255
4.
130.56.0.0
130.56.255.63
- A machine receives an IPv4 datagram. The protocol field of the IPv4 header has the protocol number of a protocol X.
Which ONE of the following is NOT a possible candidate for X? - Consider a network that uses Ethernet and IPv4. Assume that IPv4 headers do not use any options field. Each Ethernet frame can carry a maximum of 1500 bytes in its data field. A UDP segment is transmitted. The payload (data) in the UDP segment is 7488 bytes.
Which ONE of the following choices has the CORRECT total number of fragments transmitted and the size of the last fragment including IPv4 header?
