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hello all,
As I had mentioned in the previous mail I was trying to prioritise outgoing
packets on eth1 interface based on TOS value.I am testing this by sending
packets from 2 IP sources (with 2 different TOS values) at very high data rate
sending packets alternatively.On the outgoing interface I am using a sniffer to
see if the lower priority source is getting starved.
But the sniffer capture shows that packets from both sources arrive
alternatively as they are sent.I tried using default qdisc is pfifo_fast and
PRIO also.
Please anyone tell me what could be the problem.
Regards
Andreas
Chris Wilson <chris@netservers.co.uk> wrote:Hi Andreas,
I hope I have this right, based on my limited understanding of Linux QoS.
If I'm wrong then I hope someone will correct me =)
> If I just attach a PRIO qdisc on eth1(outgoing) will I be able to
> prioritise packets based on the TOS value.
You don't even need to do that, the default qdisc is pfifo_fast which also
prioritises by TOS flags.
> The TOS value is set by a test application.
It can also be overridded by a Netfilter rule, if you want to force or
change priority for certain types of packets.
> At very high data rates will the data stream with lower
> priority TOS value be starved because it cannot send out of packets from
> its band on eth1 interface?.
Yes, if there is not enough capacity to send on eth1 then lower-priority
packets will be starved, will queue up until the queue is full and then
get dropped.
> Does something be set in linux kernel so that kernel sets priority for
> packets according to TOS value.I guess this priorty will be used by PRIO
> qdisc(by default) to decide which band the packet belongs.
Yes, it happens by default, with the pfifo_fast qdisc.
Cheers, Chris.
--
___ __ _
/ __// / ,__(_)_ | Chris Wilson -- UNIX Firewall Lead Developer |
/ (_ / ,\/ _/ /_ \ | NetServers.co.uk http://www.netservers.co.uk |
\ _//_/_/_//_/___/ | 21 Signet Court, Cambridge, UK. 01223 576516 |
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<P>hello all,
<P>As I had mentioned in the previous mail I was trying to prioritise
outgoing packets on eth1 interface based on TOS value.I am testing this by
sending packets from 2 IP sources (with 2 different TOS values) at very
high data rate sending packets alternatively.On the outgoing interface I am
using a sniffer to see if the lower priority source is getting starved.
<P>But the sniffer capture shows that packets from both sources arrive
alternatively as they are sent.I tried using default qdisc is
pfifo_fast and PRIO also.
<P>Please anyone tell me what could be the problem.
<P>Regards
<P>Andreas
<P> <B><I>Chris Wilson
<chris@netservers.co.uk></I></B> wrote:
<BLOCKQUOTE style="BORDER-LEFT: #1010ff 2px solid; MARGIN-LEFT: 5px;
PADDING-LEFT: 5px">Hi Andreas,<BR><BR>I hope I have this
right, based on my limited understanding of Linux QoS. <BR>If I'm wrong
then I hope someone will correct me =)<BR><BR>> If I just
attach a PRIO qdisc on eth1(outgoing) will I be able to<BR>>
prioritise packets based on the TOS value.<BR><BR>You don't even
need to do that, the default qdisc is pfifo_fast which also
<BR>prioritises by TOS flags.<BR><BR>> The TOS value is
set by a test application.<BR><BR>It can also be overridded by a
Netfilter rule, if you want to force or <BR>change priority for certain
types of packets.<BR><BR>> At very high data rates will the
data stream with lower<BR>> priority TOS value be starved because
it cannot send out of packets from<BR>> its band on eth1
interface?.<BR><BR>Yes, if there is not enough capacity to send on
eth1 then lower-priority <BR>packets will be starved, will queue up until
the queue is full and then <BR>get dropped.<BR><BR>>
Does something be set in linux kernel so that kernel sets priority
for<BR>> packets according to TOS value.I guess this priorty will
be used by PRIO<BR>> qdisc(by default) to decide which band the
packet belongs.<BR><BR>Yes, it happens by default, with the
pfifo_fast qdisc.<BR><BR>Cheers, Chris.<BR>-- <BR>___ __
_<BR>/ __// / ,__(_)_ | Chris Wilson -- UNIX Firewall Lead Developer
|<BR>/ (_ / ,\/ _/ /_ \ | NetServers.co.uk http://www.netservers.co.uk
|<BR>\ _//_/_/_//_/___/ | 21 Signet Court, Cambridge, UK. 01223 576516
|<BR></BLOCKQUOTE><p><p><br><hr size=1><a
href="http://uk.yahoo.com/mail/tagline_xtra/?http://uk.docs.yahoo.com/mail_storage.html"><b><font
face="Arial" size="2">With Yahoo! Mail you can get a
bigger mailbox -- choose a size that fits your
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