Internet Control Message Protocol used by hosts & routers to • all the nodes using IP must have communicate network-level ICMP implemented information • ICMP msgs are only created for error reporting: the first IP fragment unreachable host, network, port, protocol warnings from routers or receivers network-layer above IP: ICMP msgs carried in IP datagrams
What is ARP?• Address Resolution Protocol• Protocol used to resolve address mapping between layer 3 addresses and layer 2 addresses in LAN. 9
Why ARP?• MAC address 48 bit unique in the LAN.• Hardware addresses are not computable from protocol address.• Used static table in ARPANET. 10
How ARP Works? 11
IGMP• IGMP is used by host receivers to join or leave a multicast host group.• IGMP is used by IPv4-based receivers.• The latest version at press time was Version 3. • IGMPv3 supports receivers that explicitly signal sources from which they wish to receive traffic.
IGMP OPERATION• IGMP is an asymmetric protocol.• Host Operations • To receive multicast datagrams, a host must join a group. To join a group, the host sends an IGMP membership report packet through an attached interface. 15
IGMP OPERATION• Multicast Router Operations • Multicast routers listen to all multicast addresses to detect membership reports. • 1. receiver (host) signals to join a group, • 2. creates an entry in the local group database. • 3. To verify group membership, multicast routers regularly send an IGMP Query message. 16