On 6/10/07, Gerrit Renker <[EMAIL PROTECTED]> wrote:
[DCCP]: Provide fallback RTT value when none is available
This implements RFC 4340, section 3.4:
"Each DCCP implementation thus defines a default round-trip time
for use when no estimate is available. This parameter should
default to not less than 0.2 seconds [...]."
In addition, the upper bound of 4 seconds for an RTT sample has now been
reduced,
to 3 seconds: to match the initial TCP RTO value as specified in [RFC 1122,
4.2.3.1].
Signed-off-by: Gerrit Renker <[EMAIL PROTECTED]>
---
net/dccp/dccp.h | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -73,9 +73,12 @@ extern void dccp_time_wait(struct sock *
#define DCCP_RTO_MAX ((unsigned)(120 * HZ)) /* FIXME: using TCP value */
-/* bounds for sampled RTT values from packet exchanges (in usec) */
+/*
+ * RTT sampling: sanity bounds and fallback RTT value from RFC 4340, section
3.4
+ */
#define DCCP_SANE_RTT_MIN 100
-#define DCCP_SANE_RTT_MAX (4 * USEC_PER_SEC)
+#define DCCP_FALLBACK_RTT (USEC_PER_SEC / 5)
+#define DCCP_SANE_RTT_MAX (3 * USEC_PER_SEC)
/* Maximal interval between probes for local resources. */
#define DCCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ / 2U))
I personally think this patch should include the changes where this
occurs in the code but I know these are in separate patches.
Signed-off-by: Ian McDonald <[EMAIL PROTECTED]>
--
Web: http://wand.net.nz/~iam4/
Blog: http://iansblog.jandi.co.nz
WAND Network Research Group
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