Supports Multicast and Broadcast

What does it mean that UDP supports Multicast and Broadcast?

UDP can send packets to multiple recipients at once using multicast (one-to-many) or broadcast (one-to-all on a local network) addressing without needing multiple connections.

Why is Multicast and Broadcast support useful in UDP?

It reduces bandwidth usage by allowing a single UDP message to be delivered to multiple recipients, making it efficient for services like video streaming, service discovery, or sensor networks.

How does UDP support Multicast and Broadcast?

UDP uses special IP addresses: Multicast (224.0.0.0 – 239.255.255.255) and Broadcast (255.255.255.255 or subnet-specific). The OS and network interface then handle the group delivery.

Where is UDP Multicast and Broadcast used?

It’s used in protocols like mDNS, DHCP, RIP, VoIP, video conferencing, and online multiplayer games for efficient one-to-many communication.

Which OSI layer does Multicast/Broadcast support belong to?

Multicast and broadcast addressing work at the Network Layer (Layer 3), while UDP (at the Transport Layer) utilizes them to deliver data to multiple recipients.

Is Multicast/Broadcast support Windows specific?

No, UDP multicast and broadcast are supported across all major platforms, including Windows, as part of standard IP and UDP behavior.

Is Multicast/Broadcast support Linux specific?

No, Linux fully supports UDP multicast and broadcast through the networking stack and socket options (SO_BROADCAST, IP_ADD_MEMBERSHIP, etc.).

Which Transport Protocol supports Multicast and Broadcast?

UDP is the primary transport protocol used for multicast and broadcast because it is connectionless and has low overhead.

Is Multicast/Broadcast used in client-server model?

Not typically. Client-server models are usually unicast. However, multicast/broadcast is common in service discovery, gaming, and sensor networks where one source communicates with many clients.

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  • In this section, you are going to learn

  • Terminology

  • Version Info

  • setup

Supports Multicast And Broadcast - Testcases

S.No

Test Case

Description

Expected Result

1

Send Broadcast Packet

Send UDP packet to broadcast address

All devices on subnet receive packet

2

Send Multicast Packet

Send UDP packet to multicast group

All group members receive packet

3

Join Multicast Group

Client joins multicast group

Client receives multicast packets

4

Leave Multicast Group

Client leaves multicast group

Client stops receiving packets

5

Broadcast on Local Subnet

Broadcast within subnet

Only local subnet devices receive

6

Broadcast Outside Subnet

Attempt broadcast outside subnet

Packet not forwarded

7

Multicast TTL = 1

Set TTL to 1

Packet not forwarded beyond local network

8

Multicast TTL > 1

Set TTL > 1

Packet forwarded across routers

9

Broadcast with Firewall

Send with firewall enabled

Packet blocked if not allowed

10

Multicast with Firewall

Send with firewall enabled

Packet blocked if not allowed

11

Broadcast with NAT

Send through NAT

Packet may be dropped or altered

12

Multicast with NAT

Send through NAT

Multicast may not be supported

13

Broadcast with VLAN

Send on VLAN

Packet limited to VLAN scope

14

Multicast with VLAN

Send on VLAN

Packet limited to VLAN scope

15

Broadcast Packet Size

Send large broadcast packet

Packet fragmented or dropped

16

Multicast Packet Size

Send large multicast packet

Packet fragmented or dropped

17

Broadcast Packet Loss

Simulate loss

Some devices may not receive

18

Multicast Packet Loss

Simulate loss

Some group members miss packet

19

Broadcast Packet Delay

Introduce delay

All devices receive with delay

20

Multicast Packet Delay

Introduce delay

Group members receive with delay

21

Broadcast Packet Duplication

Duplicate packet

Devices receive multiple copies

22

Multicast Packet Duplication

Duplicate packet

Group members receive multiple copies

23

Broadcast with QoS

Apply QoS

Packet prioritized or deprioritized

24

Multicast with QoS

Apply QoS

Packet prioritized or deprioritized

25

Broadcast with Encryption

Encrypt payload

Devices must decrypt

26

Multicast with Encryption

Encrypt payload

Group members must decrypt

27

Broadcast with Authentication

Add auth header

Devices validate sender

28

Multicast with Authentication

Add auth header

Group members validate sender

29

Broadcast with Logging

Enable logging

Packet logged on all receivers

30

Multicast with Logging

Enable logging

Packet logged on group members

31

Broadcast with Packet Sniffer

Use sniffer

Packet visible on network

32

Multicast with Packet Sniffer

Use sniffer

Packet visible to group only

33

Broadcast with Packet Tampering

Modify packet

Receivers detect corruption

34

Multicast with Packet Tampering

Modify packet

Group detects corruption

35

Broadcast with High Traffic

Send many packets

Network congestion possible

36

Multicast with High Traffic

Send many packets

Group congestion possible

37

Broadcast with Low Bandwidth

Limit bandwidth

Packet loss or delay

38

Multicast with Low Bandwidth

Limit bandwidth

Packet loss or delay

39

Broadcast with Multiple Interfaces

Send from multiple NICs

Packet sent on all interfaces

40

Multicast with Multiple Interfaces

Send from multiple NICs

Packet sent on selected interface

41

Broadcast with Loopback

Send to loopback

Packet not broadcasted

42

Multicast with Loopback

Send to loopback

Packet not multicast

43

Broadcast with IPv6

Use IPv6 broadcast

Not supported (use multicast)

44

Multicast with IPv6

Use IPv6 multicast

Packet delivered to group

45

Broadcast with Socket Reuse

Reuse socket

Multiple apps receive

46

Multicast with Socket Reuse

Reuse socket

Multiple apps receive

47

Broadcast with TTL

Set TTL

TTL ignored for broadcast

48

Multicast with Interface Binding

Bind to interface

Packet sent on bound interface

49

Broadcast with Port Conflict

Use same port

Conflict or shared delivery

50

Multicast with Port Conflict

Use same port

Conflict or shared delivery

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