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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2010-08-29 19:27:34 +0000
committerDavid S. Miller <davem@davemloft.net>2010-08-30 13:50:44 -0700
commit3d5b99ae82f8742e3bb1f8634fd11ac36ea19ee1 (patch)
tree45ecec91f84d6038e2eeba2dd81d5cee7c07e599
parent89858ad14307a398961a0f1414b04053c1475e4f (diff)
downloadlinux-3d5b99ae82f8742e3bb1f8634fd11ac36ea19ee1.tar.bz2
TCP: update initial windows according to RFC 5681
This updates the use of larger initial windows, as originally specified in RFC 3390, to use the newer IW values specified in RFC 5681, section 3.1. The changes made in RFC 5681 are: a) the setting now is more clearly specified in units of segments (as the comments by John Heffner emphasized, this was not very clear in RFC 3390); b) for connections with 1095 < SMSS <= 2190 there is now a change: - RFC 3390 says that IW <= 4380, - RFC 5681 says that IW = 3 * SMSS <= 6570. Since RFC 3390 is older and "only" proposed standard, whereas the newer RFC 5681 is already draft standard, it seems preferable to use the newer IW variant. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/tcp.h10
1 files changed, 2 insertions, 8 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index a64022199b62..11dbacc886c0 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -781,17 +781,11 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk)
/*
* Convert RFC 3390 larger initial window into an equivalent number of packets.
- *
- * John Heffner states:
- *
- * The RFC specifies a window of no more than 4380 bytes
- * unless 2*MSS > 4380. Reading the pseudocode in the RFC
- * is a bit misleading because they use a clamp at 4380 bytes
- * rather than a multiplier in the relevant range.
+ * This is based on the numbers specified in RFC 5681, 3.1.
*/
static inline u32 rfc3390_bytes_to_packets(const u32 smss)
{
- return smss <= 1095 ? 4 : (smss > 1460 ? 2 : 3);
+ return smss <= 1095 ? 4 : (smss > 2190 ? 2 : 3);
}
extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);