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,N. McKeown, D. Wischik
- Part I: buffer sizes for core routers, N. McKeown, D. Wischik
- Part II: control theory for buffer sizing, G. Raina, D. Towsley, D. Wischik
- Part III: routers with very small buffers, M. Enachescu, Y. Ganjali, A. Goel, N. McKeown, T. Roughgarden
- Sizing Router Buffers (copy), G. Appenzeller, I. Keslassy, N. McKeown, SIGCOMM'04, ACM CCR, October 2004
- The Effect of Router Buffer Size on HighSpeed TCP Performance, Dhiman Barman, Georgios Smaragdakis and Ibrahim Matta, Proc. IEEE Globecom 2004. (presentation)
- Link Buffer Sizing: a New Look at the Old Problem, Sergey Gorinsky, A. Kantawala, and J. Turner, ISCC-05, June 2005 (Technical Report WUCSE-2004-82, 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
- A Critique of Recently Proposed Buffer-Sizing Strategies, G.Vu-Brugier, R.S. Stanojevic, D.J. Leith, R.N. Shorten, ACM CCR, January 2007
- High Performance TCP in ANSNET, C. Villamizar and C. Song, ACM CCR 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
- Buffer Sizing in the Internet, Web page, Stanford University, last accessed: 2019-03-11
- Sizing Router Buffers (Redux), N. McKeown, G. Appenzeller, I. Keslassy, ACM SIGCOMM CCR, October 2019
– Main.SimonLeinen - 2005-01-07 - 2019-10-14