Ericsson released the source code for TIPC (Telecom Inter-Process Communication) to the Open Source community on February 3, 2003 under the GNU General Public License (GPL). TIPC is a specially designed protocol for intracluster communication and has been used as a part of Ericsson products for years, deployed at hundreds of sites around the globe. It is now ported to Linux and is implemented as a loadable kernel module.
TIPC is a useful toolbox for anyone wanting to develop or use carrier-grade Linux clusters. It provides the necessary infrastructure for cluster, network and software management functionality.
The functional addressing scheme seems to be unique, as is the subscription services and agile connection concept. The signaling link implementation, providing full load sharing and safe failover over any type of bearer is also an asset.
TIPC features include:
Full location transparency: TIPC provides a functional addressing scheme, hiding all aspects of the cluster's physical topology for the application programs. Mapping between functional and physical addresses is performed transparently and on the fly using a distributed, internal translation table.
Lightweight, “agile” connections: by avoiding any hidden protocol messages, the message exchange within a transaction, including connection setup, short data transfer and shutdown, can be tailor-made by the user and, hence, be made more efficient. An established connection will react to and report a problem to the application upon any kind of service failure.
Generic, adaptive, signaling link protocol: tasks that typically are implemented in the transport layer, such as retransmission, segmentation, bundling and continuity check, are pushed down to the signaling link layer. This makes the link layer more complex but provides better resource utilization and results in a more efficient stack. Signaling links are tightly supervised by a continuity check of configurable frequency and are able to detect and report link failures within a fraction of a second. Failover to redundant links in such cases is handled transparently and is disturbance-free. Signaling links are self-configuring, using a broadcast/multicast neighbour-detection protocol when possible.
Performance: TIPC transfers short (< 1KB) single messages between processors, 25-35% faster than TCP/IP and with comparable speed for larger messages. For intraprocessor messages, delivery speed is 75% better. Furthermore, by using the lightweight connection mechanism, a transaction can be performed by exchanging as few as two messages, to be compared with a minimum of nine in TCP/IP. Hence, short transactions, typical in telecom applications, can be performed in a fraction of the time of corresponding TCP transactions.
Quality of service: in-sequence, loss-free message delivery can be guaranteed in both connection-oriented and connectionless mode. In case of destination unavailability, nondelivered messages are returned to the sender along with an error code indicating the cause of the problem.
Subscription services: it is possible for application programs to subscribe for the availability/non-availability of functional and physical addresses. This means it is easy to keep track of both functional and topological changes in the cluster, as well as to synchronize the startup of distributed applications.
We are planning to write a full technical article on TIPC for LJ in the upcoming months; meanwhile, feel free to contact Jon Maloy (Jon.Maloy@Ericsson.com) to discuss any aspect of TIPC.
—Jon Maloy and Ibrahim Haddad
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