Res: Dropped Packets

Lorenz Helleis lorenzhelleis at yahoo.com.br
Fri Mar 7 16:39:34 UTC 2008


I don't think that is a hardware problem,  sometimes the "congestion rate" increase to 1500,0/s and the "state-mismatch" to 300.0/s.. I don't know if it is normal... 

I think that the conections is being droped when increase a lot the number of packets on the network. 



can you tell me about your firewall ?  I will need to install a biggest one here, and I'm a little afraid to do.   Can you show me some configuration?  the traffic of you network?, hardware? conections ?

look some configurations.... do i need to increase something ?


# pfctl -sm                                                                                                                 
states        hard limit   100000
src-nodes     hard limit    10000
frags         hard limit     5000
tables        hard limit     1000
table-entries hard limit   200000


# top

load averages:  0.20,  0.12,  0.09                                      13:29:40
35 processes:  34 idle, 1 on processor
CPU0 states:  0.6% user,  0.0% nice,  0.7% system,  0.0% interrupt, 98.7% idle
CPU1 states:  0.1% user,  0.0% nice,  0.2% system,  0.0% interrupt, 99.7% idle

# vmstat -i

interrupt                       total     rate
irq0/clock                  257506609      199
irq0/ipi                    183393879      142
irq81/em0                  8638587188     6706
irq83/skc0                 6011660768     4667
irq80/fxp0                 2292732543     1779
irq64/ahc0                    7012560        5
irq112/pckbc0                       8        0
Total                     17390893555    13501

# pfctl -si

State Table                          Total             Rate
  current entries                     5005               
  searches                     30026832082       441000.4/s
  inserts                        406964726         5977.0/s
  removals                       406959721         5977.0/s
Counters
  match                          417436387         6130.8/s
  bad-offset                             0            0.0/s
  fragment                            1939            0.0/s
  short                                154            0.0/s
  normalize                          34858            0.5/s
  memory                                 0            0.0/s
  bad-timestamp                          0            0.0/s
  congestion                        834349           12.3/s
  ip-option                             24            0.0/s
  proto-cksum                         5572            0.1/s
  state-mismatch                    491286            7.2/s




 
Provérbios 1:27 

    Mas Deus escolheu as coisas loucas deste mundo para confundir as
sábias; e Deus escolheu as coisas fracas deste mundo para confundir as
fortes;

----- Mensagem original ----
De: Chris Marlatt <cmarlatt at rxsec.com>
Para: Lorenz Helleis <lorenzhelleis at yahoo.com.br>
Cc: freebsd-pf at freebsd.org
Enviadas: Sexta-feira, 7 de Março de 2008 12:26:03
Assunto: Re: Dropped Packets

Lorenz Helleis wrote:
> hello.
> 
> I have a firewall with 75.000 simultaneous conections, and i set the limit to 100.000.
> 
> I think the hardware is OK, but when increase the traffic on the network,  some connections is dropped.  I did not increase other value, like table, src-nodes.... How do I know if is everthing ok with the other values ?
> 
> what happen if the number of connections touch the limit of 100.000 ?  it will drop the idle conections ? or what ?
> 

 From my experience new connections will appear to timeout as PF has no 
more sessions available for new connections. As sessions die off 
organically new connections will be permitted but there is nothing 
actively killing old / idle connections to make way for new sessions if 
the limit is reached.


Depending on how much memory you have you should be fine increasing the 
max session limit. I've had some of my firewalls over 1,000,000 sessions 
without a problem.

You may want to check your switch for errors and watch your interface 
(netstat -I IFACE -nd 1) to see when/where your drops are. What kind of 
cpu usage are you seeing when you start dropping the packets?

Regards,

    Chris






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