draft-ietf-opsawg-large-flow-load-balancing-12.txt   draft-ietf-opsawg-large-flow-load-balancing-13.txt 
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Dell Dell
Ning So Ning So
Tata Communications Tata Communications
B. Khasnabish B. Khasnabish
ZTE Corporation ZTE Corporation
June 13, 2014 June 13, 2014
Mechanisms for Optimizing LAG/ECMP Component Link Utilization in Mechanisms for Optimizing LAG/ECMP Component Link Utilization in
Networks Networks
draft-ietf-opsawg-large-flow-load-balancing-12.txt draft-ietf-opsawg-large-flow-load-balancing-13.txt
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. This document may not be modified, provisions of BCP 78 and BCP 79. This document may not be modified,
and derivative works of it may not be created, except to publish it and derivative works of it may not be created, except to publish it
as an RFC and to translate it into languages other than English. as an RFC and to translate it into languages other than English.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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2. Flow Categorization 2. Flow Categorization
In general, based on the size and duration, a flow can be categorized In general, based on the size and duration, a flow can be categorized
into any one of the following four types, as shown in Figure 1: into any one of the following four types, as shown in Figure 1:
(a) Short-lived Large Flow (SLLF), (a) Short-lived Large Flow (SLLF),
(b) Short-lived Small Flow (SLSF), (b) Short-lived Small Flow (SLSF),
(c) Long-lived Large Flow (LLLF), and (c) Long-lived Large Flow (LLLF), and
(d) Long-lived Small Flow (LLSF). (d) Long-lived Small Flow (LLSF).
Flow Size Flow Bandwidth
^ ^
|--------------------|--------------------| |--------------------|--------------------|
| | | | | |
Large | SLLF | LLLF | Large | SLLF | LLLF |
Flow | | | Flow | | |
|--------------------|--------------------| |--------------------|--------------------|
| | | | | |
Small | SLSF | LLSF | Small | SLSF | LLSF |
Flow | | | Flow | | |
+--------------------+--------------------+-->Flow Duration +--------------------+--------------------+-->Flow Duration
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o The presence of 2 large flows causes congestion on this o The presence of 2 large flows causes congestion on this
component link. component link.
+-----------+ -> +-----------+ +-----------+ -> +-----------+
| | -> | | | | -> | |
| | ===> | | | | ===> | |
| (1)|--------|(1) | | (1)|--------|(1) |
| | -> | | | | -> | |
| | -> | | | | -> | |
| (R1) | -> | (R2) | | (R1) | -> | (R2) |
| (2)|--------|(2) | | (2)|--------|(2) |
| | -> | | | | -> | |
| | -> | | | | -> | |
| | ===> | | | | ===> | |
| | ===> | | | | ===> | |
| (3)|--------|(3) | | (3)|--------|(3) |
| | | | | | | |
+-----------+ +-----------+ +-----------+ +-----------+
Where: -> small flow Where: -> small flow
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flow -- and the link utilization is normal now. flow -- and the link utilization is normal now.
+-----------+ -> +-----------+ +-----------+ -> +-----------+
| | -> | | | | -> | |
| | ===> | | | | ===> | |
| (1)|--------|(1) | | (1)|--------|(1) |
| | | | | | | |
| | ===> | | | | ===> | |
| | -> | | | | -> | |
| | -> | | | | -> | |
| (R1) | -> | (R2) | | (R1) | -> | (R2) |
| (2)|--------|(2) | | (2)|--------|(2) |
| | | | | | | |
| | -> | | | | -> | |
| | -> | | | | -> | |
| | ===> | | | | ===> | |
| (3)|--------|(3) | | (3)|--------|(3) |
| | | | | | | |
+-----------+ +-----------+ +-----------+ +-----------+
Where: -> small flow Where: -> small flow
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threshold defined above. threshold defined above.
. Imbalance threshold: A measure of the deviation of the . Imbalance threshold: A measure of the deviation of the
component link utilizations from the utilization of the overall component link utilizations from the utilization of the overall
LAG/ECMP group. Since component links can be of a different LAG/ECMP group. Since component links can be of a different
speed, the imbalance can be computed as follows. Let the speed, the imbalance can be computed as follows. Let the
utilization of each component link in a LAG/ECMP group with n utilization of each component link in a LAG/ECMP group with n
links of speed b_1, b_2 ... b_n, be u_1, u_2 ... u_n. The mean links of speed b_1, b_2 ... b_n, be u_1, u_2 ... u_n. The mean
utilization is computed is u_ave = [ (u_1 x b_1) + (u_2 x b_2) + utilization is computed is u_ave = [ (u_1 x b_1) + (u_2 x b_2) +
... + (u_n x b_n) ] / [b_1 + b_2 + ... + b_n]. The imbalance is ... + (u_n x b_n) ] / [b_1 + b_2 + ... + b_n]. The imbalance is
then computed as max_{i=1 ... n} | u_i - u_ave |. then computed as max_{i=1...n} | u_i - u_ave |.
. Rebalancing interval: The minimum amount of time between . Rebalancing interval: The minimum amount of time between
rebalancing events. This parameter ensures that rebalancing is rebalancing events. This parameter ensures that rebalancing is
not invoked too frequently as it impacts packet ordering. not invoked too frequently as it impacts packet ordering.
These parameters may be configured on a system-wide basis or it may These parameters may be configured on a system-wide basis or it may
apply to an individual LAG. It may be applied to an ECMP group apply to an individual LAG. It may be applied to an ECMP group
provided the component links are not shared with any other ECMP provided the component links are not shared with any other ECMP
group. group.
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10. Acknowledgements 10. Acknowledgements
The authors would like to thank the following individuals for their The authors would like to thank the following individuals for their
review and valuable feedback on earlier versions of this document: review and valuable feedback on earlier versions of this document:
Shane Amante, Fred Baker, Michael Bugenhagen, Zhen Cao, Brian Shane Amante, Fred Baker, Michael Bugenhagen, Zhen Cao, Brian
Carpenter, Benoit Claise, Michael Fargano, Wes George, Sriganesh Carpenter, Benoit Claise, Michael Fargano, Wes George, Sriganesh
Kini, Roman Krzanowski, Andrew Malis, Dave McDysan, Pete Moyer, Kini, Roman Krzanowski, Andrew Malis, Dave McDysan, Pete Moyer,
Peter Phaal, Dan Romascanu, Curtis Villamizar, Jianrong Wong, George Peter Phaal, Dan Romascanu, Curtis Villamizar, Jianrong Wong, George
Yum, and Weifeng Zhang. As a part of the IETF Last Call process, Yum, and Weifeng Zhang. As a part of the IETF Last Call process,
valuable comments were received from Martin Thomson, valuable comments were received from Martin Thomson and Carlos
Pignataro.
11. References 11. References
11.1. Normative References 11.1. Normative References
[802.1AX] IEEE Standards Association, "IEEE Std 802.1AX-2008 IEEE [802.1AX] IEEE Standards Association, "IEEE Std 802.1AX-2008 IEEE
Standard for Local and Metropolitan Area Networks - Link Standard for Local and Metropolitan Area Networks - Link
Aggregation", 2008. Aggregation", 2008.
[RFC 2991] Thaler, D. and C. Hopps, "Multipath Issues in Unicast and [RFC 2991] Thaler, D. and C. Hopps, "Multipath Issues in Unicast and
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