IPv4 Multicast Application Development

IP Multicast Application Development BOF Bob Quinn Stardust Technologies, Inc. February 8, 1998

Agenda ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

IP Multicast is... ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

IP Multicast in Action Multicast Sender Multicast Routers Data Replicated Multicast Receivers Entities: Actions: Single Data Send Data Propagated to Receivers Data Pruned where no Receivers

Multicast Application Categories ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Multicast Application Sketches ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Original Multicast API ,[object Object],[object Object],[object Object],[object Object]

Join Multicast Group ,[object Object],[object Object],[object Object],Int setsockopt( SOCKET s, int level, int optname, const char FAR*optval, int optlen); /* The structure used to add and drop multicast addresses */ typedef struct ip_mreq { struct in_addr imr_multiaddr; /* multicast group to join */ struct in_addr imr_interface; /* interface to join on */ }IP_MREQ;

IGMP v1 in Action ,[object Object],[object Object],Muliicast Receiver joins group Multicast Router stores multicast address Router protocol shares group membership info with other routers. IGMP Host Membership Report (type = 2) sent to group address when application joins group 0 32 8 16 24 version type <unused> checksum Multicast Group Address

IGMP v1 in Action ,[object Object],Muliicast Receiver joins group Multicast Router stores multicast address After random timer expires and no other responses seen,group member responds with another Host Membership Report After timeout, Router checks for current members by sending Host Membership Query (type=1) to “All Hosts” group (224.0.0.1)

Other Sockets Multicast APIs ,[object Object],[object Object],[object Object],[object Object],[object Object]

Multicast API Subtleties ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Sample Multicast Applications ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Get a UDP socket ,[object Object],[object Object],/* Get a datagram socket */ hSocket = socket(AF_INET, SOCK_DGRAM, 0); if (hSocket == INVALID_SOCKET) { printf ("socket() failed, Err: %d", WSAGetLastError()); return(-1); }

Name the socket ,[object Object],[object Object],/* Name the socket (assign port number to receive on) */ stLclAddr.sin_family = AF_INET; stLclAddr.sin_addr.s_addr = htonl(INADDR_ANY); stLclAddr.sin_port = htons(nPort); nRet = bind(hSocket, (struct sockaddr*) &stLclAddr, sizeof(stLclAddr)); if (nRet == SOCKET_ERROR) { printf ("bind() port: %d failed, Err: %d", nPort, WSAGetLastError()); }

Join the Multicast Group ,[object Object],[object Object],/* Join the multicast group so we can receive from it */ stMreq.imr_multiaddr.s_addr = inet_addr(achMCAddr); stMreq.imr_interface.s_addr = INADDR_ANY; nRet = setsockopt(hSocket, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&stMreq, sizeof(stMreq)); if (nRet == SOCKET_ERROR) { printf("IP_ADD_MEMBERSHIP address %s failed, Err: %d", achMCAddr, WSAGetLastError()); }

Receive Multicast Data ,[object Object],for (;;) { int addr_size = sizeof(struct sockaddr_in); nRet = recvfrom(hSocket, achInBuf, BUFSIZE, 0, (struct sockaddr*)&stSrcAddr, &addr_size); if (nRet < 0) { printf ("recvfrom() failed, Error: %d", WSAGetLastError()); break; } << process data received >> } /* end for(;;) */

Leave the Multicast Group ,[object Object],[object Object],/* Leave the multicast group */ stMreq.imr_multiaddr.s_addr = inet_addr(achMCAddr); stMreq.imr_interface.s_addr = INADDR_ANY; nRet = setsockopt(hSocket, IPPROTO_IP, IP_DROP_MEMBERSHIP, (char *)&stMreq, sizeof(stMreq)); if (nRet == SOCKET_ERROR) { printf ("IP_DROP_MEMBERSHIP address %s failed, Err: %d", achMCAddr, WSAGetLastError()); } /* Close the socket */ closesocket(hSocket);

In the Sender... ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],/* Set IP TTL to traverse up to multiple routers */ nRet = setsockopt(hSocket, IPPROTO_IP, IP_MULTICAST_TTL, (char *)&lTTL, sizeof(lTTL)); if (nRet == SOCKET_ERROR) { printf ("setsockopt() IP_MULTICAST_TTL failed, Err: %d", WSAGetLastError()); }

Disable Loopback ,[object Object],[object Object],/* Disable loopback */ fFlag = FALSE; nRet = setsockopt(hSocket, IPPROTO_IP, IP_MULTICAST_LOOP, (char *)&fFlag, sizeof(fFlag)); if (nRet == SOCKET_ERROR) { printf ("setsockopt() IP_MULTICAST_LOOP failed, Err: %d", WSAGetLastError()); }

Send to Multicast Address ,[object Object],[object Object],/* send to destination multicast address */ stDstAddr.sin_family = AF_INET; stDstAddr.sin_addr.s_addr = inet_addr(achMCAddr); stDstAddr.sin_port = htons(nPort); nRet = sendto(hSocket, (char *)&achBuf, sizeof(achBuf), 0, (struct sockaddr*)&stDstAddr, sizeof(stDstAddr)); if (nRet < 0) { printf ("sendto() failed, Error: %d", WSAGetLastError()); }

IGMP v2 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

IGMP V2 ,[object Object],[object Object],[object Object],[object Object],[object Object],0 32 8 16 24 type Max respns time checksum Multicast Group Address IP Router Alert option (RFC 2113) enabled in all messages

Other APIs ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Multicast Application Similarities & Differences ,[object Object],[object Object],[object Object],[object Object],[object Object]

Range of Application Requirements ,[object Object],Delay In tolerant Delay Tolerant Loss Tolerant Loss In tolerant Audio/Video Conferencing Distributed Interactive Simulations Audio/Video Streaming File Distribution Non-Essential Data: - Headline News, - Sports Scores - Weather Updates - Session Directories Stock Info & Online Auction Whiteboard Sharing Resource Discovery

QoS not tied to Multicast ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Reliability Requirements ,[object Object],[object Object],[object Object]

Can Reliable Multicast Protocols use TCP model? ,[object Object],[object Object],Multicast sender sends a single message Multicast receivers simultaneously respond with a storm of ACKs

Multicast protocols are Receiver-Based ,[object Object],[object Object],Multicast sender sends a single message Multicast receivers respond with NAKs (only) when they detect missing data

Shared Recovery ,[object Object],[object Object],[object Object],[object Object],[object Object]

Local Recovery ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Local Recovery in Action Multicast Sender Multicast Routers 3) Data Retransmitted by Recovery Designates Multicast Receivers Entities: Actions: 1) NAK Sent by Receivers after missing data detected 2) NAK detected by Recovery Designates Local Recovery Designates

Send Redundant Data ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

FEC techniques Data 7 Data 5 Data 3 Data 1 Data 2 ta 4 6 D Dat Data 8 “ Striped” Data Data 7 Parity4 Data with Parity Data 6 Parity3 Data 5 Parity2 Data 4 Parity1 These representations are simplified versions of the real thing and there are many different algorithms, but these give some FEC techniques. Notice that data is spread over time, to avoid fate sharing (due to burst errors). time time

Rate Adaptive ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Send Layered Data ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Reliable Multicast Transports - A Summary ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Other Issues with Multicast ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Solutions in the works ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

More Multicast Infrastructure ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

IGMP v3 ,[object Object],[object Object],[object Object],[object Object],[object Object],int IPMulticastListen(socket, interface, // interface as in m_req multicast-address, // group address as in m_req filter-mode, // INCLUDE or EXCLUDE source-list); // list (<64) of source addresses

Domain-Wide Group Membership Reports ,[object Object],[object Object]

Multicast Address Management Protocols ,[object Object],[object Object],[object Object],[object Object],[object Object]

Multicast Address Management Architecture MDHCP router MASC router Multicast Address Domain MASC to other Domains Client Client Server listening on well-known multicast address MDHCP Unicast MDHCP Multicast AAP or other protocols provide address ranges See http://north.east.isi.edu/malloc/ for more information

MDHCP APIs ,[object Object],[object Object],int MDhcpEnumerateScopes( IN OUT SCOPE *ScopeList, IN OUT int *ScopeListLen, OUT int *ScopeCount); typedef struct scope { int ScopeId, IP_ADDR ServerIpAddress; STRING ScopeDescription; } SCOPE;

MDHCP APIs ,[object Object],[object Object],int MDhcpRequestAddress( IN OUT REQUEST_ID *RequestUID, IN SCOPE *Scope, IN LEASE_INFO *AddrRequest, IN OUT LEASE_INFO *AddrResponse); typedef struct lease_info { TIME StartTime, TIME EndTime, int TTL; int AddrCount; IP_ADDR Address[1]; } LEASE_INFO;

MDHCP APIs ,[object Object],[object Object],int MDhcpRenewAddress( IN OUT REQUEST_ID *RequestUID, IN SCOPE *Scope, IN LEASE_INFO *RenewRequest, IN OUT LEASE_INFO *RenewResponse); int MDhcpReleaseAddress( IN OUT REQUEST_ID *RequestUID, IN SCOPE *Scope, IN int *ReleaseRequest);

Conclusions ,[object Object],[object Object],[object Object],[object Object],[object Object]

References ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

IPv4 Multicast Application Development

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