Shedding light on the glue logic of the internet routing architecture

Abstract

Recent studies reveal that the routing structures of operational networks are much more complex than a simple BGP/IGP hierarchy, highlighted by the presence of many distinct instances of routing protocols. However, the glue (how routing protocol instances interact and exchange routes among themselves) is still little understood or studied. For example, although Route Redistribution (RR), the implementation of the glue in router software, has been used in the Internet for more than a decade, it was only recently shown that RR is extremely vulnerable to anomalies similar to the permanent route oscillations in BGP. This paper takes an important step toward understanding how RR is used and how fundamental the role RR plays in practice. We developed a complete model and associated tools for characterizing interconnections between routing instances based on analysis of router configuration data. We analyzed and characterized the RR usage in more than 1600 operational networks. The findings are: (i) RR is indeed widely used; (ii) operators use RR to achieve important design objectives not realizable with existing routing protocols alone; (iii) RR configurations can be very diverse and complex. These empirical discoveries not only confirm that the RR glue constitutes a critical component of the current Internet routing architecture, but also emphasize the urgent need for more research to improve its safety and flexibility to support important design objectives.

Demystifying configuration challenges and trade-offs in network-based ISP services

“…While we focus on complexity within an ISP's network configuration, prior works [7,15,18,11] have focused on the causes for complexity in enterprises. These studies found core enterprise network designs to be complex due to the usage of VLANs, routeredistribution commands, and network security and filtering policies.…”

Discovering configuration templates of virtualized tenant networks in multi-tenancy datacenters via graph-mining

“…There have been various efforts on analyzing network configuration files. Configuration files have been used mostly in understanding network characteristics such as routing design [12], Class-ofService [13], Route Redistribution [14], complexity of enterprise network [10], access control lists [15], co-occurrence of device updates [16], operational history [17], and longitudinal trends in ISP services [11] and campus networks [18]. Ref.…”

A Model of Internet Routing Using Semi-modules

“…Recent research has documented their widespread use and illustrated routing anomalies that can arise as a result [3,4,5]. From our point of view, that work represents a bottom-up approach that starts with the complex implementation details of current legacy software.…”

“…Administrative distance [3,4,5] is used for determining which entries are placed in a forwarding table when distinct protocols running on the same router have routes to common destinations. Algebraic modeling of administrative distance remains open for a careful formal treatment.…”

“…In Section 4 we discuss how this model is related to current rethinking of the Internet's addressing architecture (see for example John Day's book [2]), and to existing problems with route redistribution [3,4,5]. For completeness, Appendix A supplies definitions of semirings and semi-modules.…”