Re: Increasing interface queues
From: Archie Cobbs (archie_at_dellroad.org)
Date: 07/23/03
- Previous message: Michael Sierchio: "Re: NAT and PPTP"
- In reply to: Mike Tancsa: "Increasing interface queues"
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To: Mike Tancsa <mike@sentex.net> Date: Tue, 22 Jul 2003 20:55:58 -0700 (PDT)
Mike Tancsa wrote:
> We have a box terminating a lot of MPD tunnels from dialup
> connections. When the modems at remote sites renegotiate due to poor line
> quality, there will be a pause in the flow of data. Occasionally, the
> interface on the terminating side will get a "no buffer space" as data is
> accumulating to be sent out. Is there a way for me to increase those queue
> sizes so that the server's queue has more room to hold the data until the
> other end is ready to receive again ?
>
> The only sysctl var I could see
> % sysctl -a | grep -i queue
> net.inet.ip.intr_queue_maxlen: 50
> net.inet.ip.intr_queue_drops: 0
> p1003_1b.sigqueue_max: 0
>
> I dont think is related to this issue.
The ENOBUFS is coming from ng_pptpgre(4) and really means "the PPTP
transmit window is full". The fact that PPTP has such a window is
itself a bug (L2TP is better). But in any case increasing that queue
length is not the right answer.. you actually want short queues (just
long enough to handle burstiness in the flow of packets) to avoid
excessive latency, and to let TCP etc. do its thing.
If you want ng_pptpgre(4) to just silently drop the packets instead
apply the patch below.
-Archie
__________________________________________________________________________
Archie Cobbs * Halloo Communications * http://www.halloo.com
Index: ng_pptpgre.c
===================================================================
RCS file: /home/ncvs/src/sys/netgraph/ng_pptpgre.c,v
retrieving revision 1.2.2.13
diff -u -r1.2.2.13 ng_pptpgre.c
--- ng_pptpgre.c 10 Oct 2002 18:27:54 -0000 1.2.2.13
+++ ng_pptpgre.c 23 Jul 2003 03:55:52 -0000
@@ -491,7 +491,7 @@
>= a->xmitWin) {
priv->stats.xmitDrops++;
NG_FREE_DATA(m, meta);
- return (ENOBUFS);
+ return (0);
}
/* Sanity check frame length */
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- Previous message: Michael Sierchio: "Re: NAT and PPTP"
- In reply to: Mike Tancsa: "Increasing interface queues"
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