PCN-Based Flow Termination with Multiple Bottleneck Links

Pre-congestion notification (PCN) is a new packet marking scheme based on which simple measurement-based admission control (AC) and flow termination (FT) are implemented. FT is useful for traffic management in unexpected events, e.g., when admitted flows lead to overload on a link after rerouting which may be due to a link or node failure. While AC is a classic flow control function, FT is new and only little understood so far. The limited literature on FT focuses mainly on a single overloaded link. However, when a link or node fails, redirected traffic is likely to cause overload on multiple backup links (bottlenecks) at the same time. As the packet marking probability for flows traversing multiple bottlenecks is larger than for flows traversing only the most severe bottleneck, more traffic is possibly terminated than needed, i.e. over termination occurs. This paper quantifies potential over termination in case of multiple bottlenecks for different FT mechanisms which are currently discussed by the IETF.