Documentation: add more details in tipc.rst

kernel-doc for TIPC is too simple, we need to add more information for it.

This patch is to extend the abstract, and add the Features and Links items.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/tipc.rst

@@ -4,10 +4,125 @@
 Linux Kernel TIPC
 =================
 
-TIPC (Transparent Inter Process Communication) is a protocol that is
-specially designed for intra-cluster communication.
+Introduction
+============
 
-For more information about TIPC, see http://tipc.sourceforge.net.
+TIPC (Transparent Inter Process Communication) is a protocol that is specially
+designed for intra-cluster communication. It can be configured to transmit
+messages either on UDP or directly across Ethernet. Message delivery is
+sequence guaranteed, loss free and flow controlled. Latency times are shorter
+than with any other known protocol, while maximal throughput is comparable to
+that of TCP.
+
+TIPC Features
+-------------
+
+- Cluster wide IPC service
+
+  Have you ever wished you had the convenience of Unix Domain Sockets even when
+  transmitting data between cluster nodes? Where you yourself determine the
+  addresses you want to bind to and use? Where you don't have to perform DNS
+  lookups and worry about IP addresses? Where you don't have to start timers
+  to monitor the continuous existence of peer sockets? And yet without the
+  downsides of that socket type, such as the risk of lingering inodes?
+
+  Welcome to the Transparent Inter Process Communication service, TIPC in short,
+  which gives you all of this, and a lot more.
+
+- Service Addressing
+
+  A fundamental concept in TIPC is that of Service Addressing which makes it
+  possible for a programmer to chose his own address, bind it to a server
+  socket and let client programs use only that address for sending messages.
+
+- Service Tracking
+
+  A client wanting to wait for the availability of a server, uses the Service
+  Tracking mechanism to subscribe for binding and unbinding/close events for
+  sockets with the associated service address.
+
+  The service tracking mechanism can also be used for Cluster Topology Tracking,
+  i.e., subscribing for availability/non-availability of cluster nodes.
+
+  Likewise, the service tracking mechanism can be used for Cluster Connectivity
+  Tracking, i.e., subscribing for up/down events for individual links between
+  cluster nodes.
+
+- Transmission Modes
+
+  Using a service address, a client can send datagram messages to a server socket.
+
+  Using the same address type, it can establish a connection towards an accepting
+  server socket.
+
+  It can also use a service address to create and join a Communication Group,
+  which is the TIPC manifestation of a brokerless message bus.
+
+  Multicast with very good performance and scalability is available both in
+  datagram mode and in communication group mode.
+
+- Inter Node Links
+
+  Communication between any two nodes in a cluster is maintained by one or two
+  Inter Node Links, which both guarantee data traffic integrity and monitor
+  the peer node's availability.
+
+- Cluster Scalability
+
+  By applying the Overlapping Ring Monitoring algorithm on the inter node links
+  it is possible to scale TIPC clusters up to 1000 nodes with a maintained
+  neighbor failure discovery time of 1-2 seconds. For smaller clusters this
+  time can be made much shorter.
+
+- Neighbor Discovery
+
+  Neighbor Node Discovery in the cluster is done by Ethernet broadcast or UDP
+  multicast, when any of those services are available. If not, configured peer
+  IP addresses can be used.
+
+- Configuration
+
+  When running TIPC in single node mode no configuration whatsoever is needed.
+  When running in cluster mode TIPC must as a minimum be given a node address
+  (before Linux 4.17) and told which interface to attach to. The "tipc"
+  configuration tool makes is possible to add and maintain many more
+  configuration parameters.
+
+- Performance
+
+  TIPC message transfer latency times are better than in any other known protocol.
+  Maximal byte throughput for inter-node connections is still somewhat lower than
+  for TCP, while they are superior for intra-node and inter-container throughput
+  on the same host.
+
+- Language Support
+
+  The TIPC user API has support for C, Python, Perl, Ruby, D and Go.
+
+More Information
+----------------
+
+- How to set up TIPC:
+
+  http://tipc.io/getting_started.html
+
+- How to program with TIPC:
+
+  http://tipc.io/programming.html
+
+- How to contribute to TIPC:
+
+- http://tipc.io/contacts.html
+
+- More details about TIPC specification:
+
+  http://tipc.io/protocol.html
+
+
+Implementation
+==============
+
+TIPC is implemented as a kernel module in net/tipc/ directory.
 
 TIPC Base Types
 ---------------