Sizing of Network Buffers

Where temporary congestion cannot be avoided, some buffering in network nodes is required (in routers and other packet-forwarding devices such as Ethernet or MPLS switches) to queue incoming packets until they can be transmitted. The appropriate sizing of these buffers has been a subject of discussion for a long time.

Traditional wisdom recommends that a network node should be able to buffer an end-to-end round-trip time's worth of line-rate traffic, in order to be able to accomodate bursts of TCP traffic. This recommendation is often followed in "core" IP networks. For example, FPC (Flexible PIC Concentrators) on Juniper's M- and T-Series routers contain buffer memory for 200ms (M-series) or 100ms (T-series) at the supported interface bandwidth (cf. Juniper M-Series Datasheet and a posting from 8 May, 2005 by Hannes Gredler to the juniper-nsp mailing list.) These ideas also influenced RFC 3819, Advice for Internet Subnetwork Designers.

Recent research results suggest that much smaller buffers are sufficient when there is a high degree of multiplexing of TCP streams.

This work is highly relevant, because overly large buffers not only require more (expensive high-speed) memory, but bring about a risk of high delays that affect perceived quality of service; see BufferBloat.

References

ACM SIGCOMM Computer Communications Review

The October 2006 edition has a short summary paper on router buffer sizing. If you read one article, read this!

The July 2005 edition (Volume 35 , Issue 3) has a special feature about sizing router buffers, containing of these articles:
Making router buffers much smaller
Nick McKeown, Damon Wischik
Part I: buffer sizes for core routers
Nick McKeown, Damon Wischik
Part II: control theory for buffer sizing
Gaurav Raina, Don Towsley, Damon Wischik
Part III: routers with very small buffers
Mihaela Enachescu, Yashar Ganjali, Ashish Goel, Nick McKeown, Tim Roughgarden

Sizing Router Buffers (copy)
Guido Appenzeller Isaac Keslassy Nick McKeown, SIGCOMM'04, in: ACM Computer Communications Review 34(4), pp. 281--292

The Effect of Router Buffer Size on HighSpeed TCP Performance
Dhiman Barman, Georgios Smaragdakis and Ibrahim Matta. In Proceedings of IEEE Globecom 2004. (PowerPoint presentation)

Link Buffer Sizing: a New Look at the Old Problem
Sergey Gorinsky, A. Kantawala, and J. Turner, ISCC-05, June 2005
Another version was published as Technical Report WUCSE-2004-82, Department of Computer Science and Engineering, Washington University in St. Louis, December 2004.

Effect of Large Buffers on TCP Queueing Behavior
Jinsheng Sun, Moshe Zukerman, King-Tim Ko, Guanrong Chen and Sammy Chan, IEEE INFOCOM 2004

High Performance TCP in ANSNET
C. Villamizar and C. Song., in: ACM Computer Communications Review, 24(5), pp.45--60, 1994

RFC 3819, Advice for Internet Subnetwork Designers
P. Karn, Ed., C. Bormann, G. Fairhurst, D. Grossman, R. Ludwig, J. Mahdavi, G. Montenegro, J. Touch, L. Wood. July 2004

-- SimonLeinen - 2005-01-07 - 2013-04-03

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