Re: [LARTC] use 3rd octet as hashkey

[Martin Volf <mv@inv.cz>]

On Mon, 24 Nov 2003 09:52:30 +0530
"Venkatesh. K" <venkatesh@cbayscribe.com> wrote:

> Hi,
> 
> I want to use 3rd octet in the ip address for creating hashng filters?
> 
> How do I do it?

Hi,

what about this (two level hashing with the 3rd and the 4th octet):


FILTER_ADD="/sbin/tc filter add dev imq0 parent 1:0 protocol ip"

# 1st level - 3rd octet (mask 0x0000ff00)
$FILTER_ADD handle 2: u32 divisor 256
$FILTER_ADD u32 ht 800:: match ip dst 0/0 \
	hashkey mask 0x0000ff00 at 16 link 2:

# 2nd level - 4th octet (mask 0x000000ff)
for i in $(seq 0 255); do
	n=$(printf "%x" $i)
	$FILTER_ADD handle $n: u32 divisor 256
	$FILTER_ADD u32 ht 2:$n match ip dst 0/0 \
		hashkey mask 0x000000ff at 16 link $n:
done

# hexa 10.11.12.13 -> c:d
hexa()
{
	local IFS='.'
	set $1
	printf "%x:%x" $3 $4
}

# example: put 10.11.12.13 into the class 1:42
ip\x10.11.12.13
$FILTER_ADD u32 ht $(hexa $ip) match ip dst $ip flowid 1:42


Something like that is working for me for about half a year. If you need "match ip src", use "at 12" instead of "at 16".

HTH

-- 
Martin Volf
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