Pf in 4.11

Christopher McGee chris at xecu.net
Thu May 12 11:35:26 PDT 2005


Chris Dionissopoulos wrote:

> My 2 cents:
>
> 1. 5000 qlimit packets is a HUGE value:
> This means, that your buffer is 5000 x 1000( avg. mtu) = 5mbytes.
> For 20Mbps queue-speed, it takes 32000 ms (32sec) to fill and then
> letting altq decide for adding or not  (0.1-500 ms) delays.
> Doesn't makes sense, eh?
> Try a more reasonable value of 50 for speeds 10-100MBps.
>
> 2.Try enabling red (or rio) in "queue1". This early detects "queue1" 
> congestion and drops packets before queue rate limit reached.
>
>
> Tell us, if you have a better 'queue0' behavior with these changes.
>
> Chris.
>
>>
>> When queue1 starts pushing it's maximum bandwidth, queue0(the 
>> default) seems to choke and services become unavailable from the 
>> outside.  I cut back queue1 by about 7 mbit/s and it has cleared it 
>> up for the most part.  Not completely though.  Here's what I think is 
>> the relevant info, let me know if you need anything else:
>>
>> The box:
>> CPU: Intel(R) Pentium(R) 4 CPU 2.00GHz (1999.78-MHz 686-class CPU)
>> real memory  = 1071906816 (1022 MB)
>> avail memory = 1039392768 (991 MB)
>> fxp0-6, only 0, and 1 are being used, the others are for future 
>> projects, like pfsync, and some dmz type stuff.
>>
>> pf configuration:
>> set limit { states 100000, frags 5000 }
>> set loginterface $ext_if
>> set block-policy drop
>> all other options are default
>>
>> queue configuration:
>> altq on $ext_if bandwidth 25Mb cbq queue { queue0, queue1 }
>> queue queue0 bandwidth 8Mb priority 4 qlimit 150 cbq(default, borrow)
>> queue queue1 bandwidth 12Mb qlimit 5000
>> the additional bandwidth that is not included in the queues should be 
>> added to queue1 but when that is done, it causes problems.  At high 
>> traffic times, queue will use ALL of its bandwidth and queue0 usually 
>> only uses 3-5megs.
>>
>> There is no nat or anything running on this firewall.  Public IP 
>> addresses outside and inside.  I would rather not revert to 4.x if 
>> possible but I can't have this machine unstable.
>>
>> Thanks,
>> Chris
>>
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>
>
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The reason the queue size was changed was because the queue was getting 
filled very quickly and there were TONS of dropped packets.  I will try 
RED and see if it gives me better results.  I'll let you know.



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