[Cake] act_conndscp

[Kevin Darbyshire-Bryant]

And another - sorry! - some stats/info

overlimits counts the number of packets that have had their DSCP overwritten/restored/set
requeues counts the number of times the ’statemask’ bit has been SET.

root at Router:~# tc -s filter show dev eth0
filter parent cacf: protocol all pref 10 u32 chain 0 
filter parent cacf: protocol all pref 10 u32 chain 0 fh 800: ht divisor 1 
filter parent cacf: protocol all pref 10 u32 chain 0 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1 not_in_hw 
  match 00000000/00000000 at 0
	action order 1: conndscp zone 0 pipe
	 index 1 ref 1 bind 1 mask 0xfc000000 statemask 0x01000000 mode both installed 218013 sec used 0 sec
	Action statistics:
	Sent 1048008900 bytes 7586620 pkt (dropped 0, overlimits 5263898 requeues 87634) 
	backlog 0b 0p requeues 87634

So the above shows that 5263898 packets had their DSCP values set based on a stored DSCP value and thus avoided going through the iptables rules.  87634 packets set that stored value.


root at Router:~# tc -s filter show dev eth0 ingress
filter parent ffff: protocol all pref 10 u32 chain 0 
filter parent ffff: protocol all pref 10 u32 chain 0 fh 800: ht divisor 1 
filter parent ffff: protocol all pref 10 u32 chain 0 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1 not_in_hw 
  match 00000000/00000000 at 0
	action order 1: conndscp zone 0 pipe
	 index 2 ref 1 bind 1 mask 0xfc000000 statemask 0x01000000 mode set installed 218027 sec used 0 sec
	Action statistics:
	Sent 7942289574 bytes 9601486 pkt (dropped 0, overlimits 6153697 requeues 0) 
	backlog 0b 0p requeues 0

	action order 2: mirred (Egress Redirect to device ifb4eth0) stolen
 	index 1 ref 1 bind 1 installed 218027 sec used 0 sec
 	Action statistics:
	Sent 7942289574 bytes 9601486 pkt (dropped 0, overlimits 0 requeues 0) 
	backlog 0b 0p requeues 0

The above shows that 6153697 packets had their DSCP values restored from the stored mark value.  Note DSCPs are only restored if they’re actually different from the current stored value, so a default DSCP of 0 on an egress path is unlikely to generate a whole load of unnecessary DSCP overwriting on the ingress path.

Does any of this help?

Kevin

> On 20 Mar 2019, at 09:06, Kevin Darbyshire-Bryant <kevin at darbyshire-bryant.me.uk> wrote:
> 
> Addendum: If not obvious.  There are two separate instances of ‘conndscp’, one on the egress path (in ‘both’ mode) and one on the ingress path (in ’set’ mode)
> 
> Cheers,
> 
> Kevin D-B
> 
> gpg: 012C ACB2 28C6 C53E 9775  9123 B3A2 389B 9DE2 334A
> 
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Cheers,

Kevin D-B

gpg: 012C ACB2 28C6 C53E 9775  9123 B3A2 389B 9DE2 334A