LARTC - Jun 2007 - ip route tos not always work

Dear All,

I need to setup different route with different tos value.

I can use the flowing command to add a tos route to routing table.
ip route 192.168.0.2/32 via 192.168.0.1 tos 0x1c and
ip route 192.168.0.2/32 via 192.168.0.1 tos 0x40

I used "ping -Q" to test it with different tos, the output packet is
marked correctly.

The problem that is only the tos value defined at
/etc/iproute/rt_dsfield can route base on the tos route. tos 0x1c work
but 0x40 not work.

Do any one know why?
Thank you!
-- 
Regards,
Michael Chung Pui Kei
Computer Engineering Year 3
School of Engineering
Hong Kong University of Science and Technology

Email Address: eg_cpkaa@stu.ust.hk

Dear List,

In order to address inaccurate results using either TBF or HTB according to:
http://www.docum.org/docum.org/faq/cache/40.html

or

"In order to increase the accuracy of the clock we can modify some
parameters of the kernel. The parameters we have tried to change
have been the PSCHED_CLOCK_SOURCE variable and the HZ variable. The observed
effect has been a small increase in the use
of the CPU, but a great improvement regarding the accuracy of the output bit
rate of the flows. The CBQ scheduler guarantees a
minimum bandwidth better and TBF obtains an output rate more adjusted to
what is required."
https://www.tlm.unavarra.es/~eduardo/publicaciones/20010403-alcom-english.pdf

It seems that the best setting for a dedicated box to shape traffic in the
network is to build a kernel with:
CONFIG_NET_SCHED=y
CONFIG_NET_SCH_CLK_CPU=y

But since NET_SCH_CLK_CPU depends on ((X86_TSC || X86_64) && !SMP),

Does this mean that the ideal Bandwidth Management box has to use only one
CPU?

The following link also suggests  the use of preemption:
CONFIG_PREEMPT=y
CONFIG_PREEMPT_BKL=y
http://www.sigsegv.cx/qos-2.html



Any thoughts? What are the best kernel settings for a Bandwidth Management
box in bridge mode using X86 architecture?


Regards,

Mario Antonio