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LKSCTP number of retransmissions

0 votes

It seems like setting the maximum number of retransmissions per packet is not implemented in the linux kernel implementation of SCTP?

Can anyone please confirm that?

posted May 16, 2013 by anonymous

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1 Answer

0 votes

Possibly you are looking for the PR-SCTP policy which limit the number of retransmissions. See
It is implemented in FreeBSD and will be used for RTCWeb.

answer May 16, 2013 by anonymous
That's exactly what I'm looking for :-)
I'm actually wanting to do some RTCWeb related experiments and am looking for an SCTP stack that supports that policy.

I take it that means that it's not implemented in the linux kernel version. I saw some activity in 2008 related to patching lksctp for that, but I'm guessing the patches weren't accepted.
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+1 vote

I wonder if it's possible to know how many retransmissions have been done by the SCTP stack when sending/receiving message (ideally by association) ? It could be a useful measure of network quality with [distant] peers.

I am using kernel SCTP...

0 votes

We are using LKSCTP version 1.0.16 and have configured the SCTP configuration parameters as follows:

SctpInitMaxAttempts : 10
SctpInitRTO : 3000
SctpMinRTO : 1000
SctpMaxRTO : 60000

We observed that SCTP:INIT re-transmission is occurring at interval 6,12,24.., 6,12,24.., 6,12,24....... As per our understanding re-transmission should occur at interval 3,6,12,24..., 3,6,12,24...3,6,12,24... since SctpInitRTO=3000.

Could you please let us know if it is an expected behavior or not. Also why re-transmission interval is not started with 3,6,12,24...

+2 votes

Is LKSCTP 100% compliant with the following?

RFC 2960 - SCTP (obsoleted by RFC 4960)
RFC 3309 - SCTP Checksum Change (obsoleted by RFC 4960)
RFC 3758 - SCTP Partial Reliability Extension
RFC 4460 - SCTP Errata and Issues
RFC 4895 - Authenticated Chunks for SCTP
RFC 4960 - SCTP
RFC 5061 - SCTP Dynamic Address Reconfiguration
RFC 5062 - Security Attacks Against SCTP

Any pointers are welcome?

+4 votes

Are the values in /proc/sys/net/sctp/sctp_[rw]mem honored? Or are they overridden by those in /proc/sys/net/core/[rw]mem_*

Furthermore, the kernel documentation states that sctp_wmem has no effect, but makes no such mention for sctp_mem and sctp_rmem.