Randy's Work Blog

RFC 7196
Title: Making Route Flap Damping Usable
Author: C. Pelsser, R. Bush,
K. Patel, P. Mohapatra,
O. Maennel
Status: Standards Track
Stream: IETF
Date: May 2014
Mailbox: cristel@iij.ad.jp,
randy@psg.com,
keyupate@cisco.com,
mpradosh@yahoo.com,
o@maennel.net
Pages: 8
Characters: 15202
Updates/Obsoletes/SeeAlso: None
I-D Tag: draft-ietf-idr-rfd-usable-04.txt
URL: http://www.rfc-editor.org/rfc/rfc7196.txt

Route Flap Damping (RFD) was first proposed to reduce BGP churn in routers. Unfortunately, RFD was found to severely penalize sites for being well connected because topological richness amplifies the number of update messages exchanged. Many operators have turned RFD off. Based on experimental measurement, this document recommends adjusting a few RFD algorithmic constants and limits in order to reduce the high risks with RFD. The result is damping a non-trivial amount of long-term churn without penalizing well-behaved prefixes’ normal convergence process.

Nejc Skoberne, Olaf Maennel, Iain Phillips, Randy Bush, Jan Zorz, and Mojca Ciglaric, IPv4 Address Sharing Mechanism Classification and Tradeoff Analysis, IEEE/ACM Transactions On Networking April 2014.

The growth of the Internet has made IPv4 addresses a scarce resource. Due to slow IPv6 deployment, IANA-level IPv4 address exhaustion was reached before the world could transition to an IPv6-only Internet. The continuing need for IPv4 reachability will only be supported by IPv4 address sharing. This paper reviews ISP-level address sharing mechanisms, which allow Internet service providers to connect multiple customers who share a single IPv4 address. Some mechanisms come with severe and un- predicted consequences, and all of them come with tradeoffs. We propose a novel classification, which we apply to existing mechanisms such as NAT444 and DS-Lite and proposals such as 4rd, MAP, etc. Our tradeoff analysis reveals insights into many problems including: abuse attribution, performance degradation, ad- dress and port usage efficiency, direct inter-customer communication, and availability.