Network-wide migrations of a running network, such as the replacement of a routing protocol or the modification of its configuration, can improve the scalability, manageability, security or the performances of the entire network. However, such migrations are an important source of concerns for network operators as the reconfiguration campaign can lead to long and service-affecting outages. In this work, we propose several techniques to address the problem of seamlessly (i.e. without loosing IP packets) modifying the configuration of commonly used routing-protocols.

Additional resources

• SEAMLESS_IGP_MIGRATIONS_GEANT.tar.gz. This archive contains all the configurations generated for and during the GEANT case study. The following directories are defined:
  • GEANT_INITIAL_CONFIGS/ : contains the initial (Cisco IOS) configurations for the 36 routers of GEANT
  • GEANT_ITERATION#X_to_GEANT_ITERATION#Y : contains the deltas configurations that permit to migrate from the state X to the state Y.
  • Four states (i.e. ITERATION) are defined:
    • ITERATION1: flat IS-IS only
    • ITERATION2: flat IS-IS (preferred) and hierarchical OSPF (not preferred)
    • ITERATION3: flat IS-IS (not preferred) and hierarchical OSPF (preferred)
    • ITERATION4: hierarchical OSPF only
  • The intermediate configurations are exscript scripts (see https://github.com/knipknap/exscript/wiki). They are used to interact directly with the routers via SSH/telnet.
• geant.entf.zip: This file represents the hierarchical topology used in the Geant use-case

References

Laurent Vanbever, Stefano Vissicchio, Cristel Pelsser, Pierre Francois and Olivier Bonaventure. Seamless Network-Wide IGP Migrations. Proceedings of the 2011 ACM SIGCOMM Conference, Toronto, Canada, Aug. 2011. ACM. Available online: here.

Laurent Vanbever, Stefano Vissicchio, Cristel Pelsser, Pierre Francois and Olivier Bonaventure. Seamless Network-Wide IGP Migrations. Tech. Rep. June 2011. http://hdl.handle.net/2078.1/75312. Also available here