Many security and QoS functions have been deployed at edge gateways to provide policy-based network management. For QoS functions, the bandwidth management system can manage the narrow WAN access links. When managing the TCP traffic, pass-through TCP flows can introduce large buffer requirement, latency, buffer overflows, and unfairness among flows competing for the same queue. This study evaluates possible TCP-aware approaches through self-developed implementations in Linux, testbed emulation, and live WAN measurement. The widely deployed TCP rate control (TCR) approach is found to be more vulnerable to WAN packet losses and less compatible to several TCP sending operating systems. The proposed PostACK approach can preserve TCR's advantages while avoiding TCR's drawbacks. PostACK emulates per-flow queuing but relocates the queuing of data to the queuing of ACKs in the reverse direction, hence minimizes buffer requirement up to 96%. PostACK also has 10% goodput improvement against TCR under lossy WAN. Experimental results can be reproduced through our open sources: (1) tcp-masq: a modified Linux kernel; (2) wan-emu: a testbed for conducting switched LAN-to-WAN or WAN-to-LAN experiments with RTT/loss/jitter emulations.
[1]
QUTdN QeO,et al.
Random early detection gateways for congestion avoidance
,
1993,
TNET.
[2]
Ying-Dar Lin,et al.
Building an integrated security gateway: Mechanisms, performance evaluations, implementations, and research issues
,
2002,
IEEE Communications Surveys & Tutorials.
[3]
Sally Floyd,et al.
Promoting the use of end-to-end congestion control in the Internet
,
1999,
TNET.
[4]
Shivkumar Kalyanaraman,et al.
TCP rate control
,
2000,
CCRV.
[5]
Van Jacobson,et al.
Link-sharing and resource management models for packet networks
,
1995,
TNET.
[6]
Scott Shenker,et al.
Analysis and simulation of a fair queueing algorithm
,
1989,
SIGCOMM 1989.
[7]
Eitan Altman,et al.
A stochastic model of TCP/IP with stationary random losses
,
2000,
SIGCOMM.
[8]
I. Damgård,et al.
The protocols.
,
1989,
The New Zealand nursing journal. Kai tiaki.
[9]
Donald F. Towsley,et al.
Modeling TCP throughput: a simple model and its empirical validation
,
1998,
SIGCOMM '98.
[10]
W. Richard Stevens,et al.
TCP/IP Illustrated, Volume 1: The Protocols
,
1994
.
[11]
Hari Balakrishnan,et al.
Network Working Group
,
1991
.