Swing state: Consistent updates for stateful and programmable data planes

Authors: Shouxi Luo, Hongfang Yu, and Laurent Vanbever
SOSR '17: Proceedings of the Symposium on SDN Research


With the rise of stateful programmable data planes, a lot of the network functions that used to be implemented in the controller or at the end-hosts are now moving to the data plane to benefit from line-rate processing. Unfortunately, stateful data planes also mean more complex network updates as not only flows, but also the associated states, must now be migrated consistently to guarantee correct network behaviors. The main challenge is that data-plane states are maintained at line rate, according to possibly runtime criteria, rendering controller-driven migration impossible.

We present Swing State, a general state-management framework and runtime system supporting consistent state migration in stateful data planes. The key insight behind Swing State is to perform state migration entirely within the data plane by piggybacking state updates on live traffic. To minimize the overhead, Swing State only migrates the states that cannot be safely reconstructed at the destination switch.

We implemented a prototype of Swing State for P4. Given a P4 program, Swing State performs static analysis to compute which states require consistent migration and automatically augments the program to enable the transfer of these states at runtime. Our preliminary results indicate that Swing State is practical in migrating data-plane states at line rate with small overhead.



	isbn = {978-1-4503-4947-5},
	doi = {10.1145/3050220.3050233},
	year = {2017-04-03},
	booktitle = {SOSR '17: Proceedings of the Symposium on SDN Research},
	type = {Conference Paper},
	author = {Luo, Shouxi and Yu, Hongfang and Vanbever, Laurent},
	keywords = {Network updates; Software-De ned Networking; P4; Stateful programmable data planes},
	language = {en},
	address = {New York, NY},
	publisher = {Association for Computing Machinery},
	title = {Swing state: Consistent updates for stateful and programmable data planes},
	PAGES = {115 - 121},
	Note = {Symposium on SDN Research (SOSR '17); Conference Location: Santa Clara, CA, USA; Conference Date: April 3-4, 2017}

Research Collection: 20.500.11850/192035