Problems in using SCTP CMT

Andrew Chen b93502044 at ntu.edu.tw
Mon Mar 23 03:44:32 PDT 2009


Hi,
	We have some problems when we tried to send data using CMT-SCTP.  
Actually, we are not sure if we do enable CMT functionalities. We set  
up two PCs with FreeBSD-7.0. Each PC has two NICs and two IPs. One is  
public and the other is private. We wrote simple FTP server and client  
programs. On both sides, local addresses are bound as INADDR_ANY.  
According to  
http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-14#section-4.1.5
, if we bind INADDR_ANY and then call connect(), the multi-homing  
capability of SCTP is automatically enabled. Further, we also turn on  
sysctl states by setting
sysctl net.inet.sctp.cmt_pf=1
sysctl net.inet.sctp.cmt_use_dac=1
sysctl net.inet.sctp.cmt_on_off=1
	Then we start transmission and capture the traffics. Unfortunately,  
the captured packet shows data were transmitted on primary path and  
there were only heartbeat/HB ACKs on the other path.
	To our knowledge, to use CMT, the only things we have to do is to  
establish a multihomed association, and turn on the sysctl options.
	Can anyone point out something we did wrong or steps we missed?
	Thanks in advance.



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