capturing packets on 250mb link

[Ganbold]

Vlad,


Vlad GALU wrote:
> On 4/28/08, Ganbold <ganbold at micom.mng.net> wrote:
>   
>> Hi all,
>>
>>  What is the best way to capture packets on 250mb link?
>>  What kernel features/modules or tools (less CPU/RAM overhead) should I use?
>>     
>
>     Given your OS version, I'd say that setting the BPF buffer size to
> around 1MB and setting the monitor flag on the capture interface would
> give you very good results. In that combination we've been doing
> packtet capture at gigabit speeds without packet loss.
>   

Thanks Vlad. So then it means something like following will work in our 
case:

#sysctl net.bpf.bufsize: 1048576
#ifconfig bge1 monitor up
#tcpdump -i bge1 -s0 -w capture.log -C 2048 -W 100

Correct me if I'm wrong here.

thanks,

Ganbold


>   
>>  I have FreeBSD 7.0-STABLE machine (
>>  CPU: Intel(R) Xeon(TM) CPU 2.80GHz (2822.51-MHz 686-class CPU),
>>  FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
>>  1GM RAM, ad2: 76319MB <Maxtor 6L080M0 BANC1G10> at ata1-master SATA150).
>>
>>  #uname -an
>>  FreeBSD ng1.micom.mng.net 7.0-STABLE FreeBSD 7.0-STABLE #3: Sat Apr 26
>> 14:08:06 ULAT 2008     tsgan at ng1.micom.mng.net:/usr/obj/usr/src/sys/NG  i386
>>
>>  #pciconf -lv|more
>>  ...
>>  bge0 at pci0:2:0:0:        class=0x020000 card=0x1659103c chip=0x165914e4
>> rev=0x11 hdr=0x00
>>    vendor     = 'Broadcom Corporation'
>>    device     = 'BCM5721 NetXtreme Gigabit Ethernet PCI Express'
>>    class      = network
>>    subclass   = ethernet
>>  ...
>>
>>  Are there any considerations on hardware?
>>
>>  thanks in advance,
>>
>>  Ganbold
>>
>>  --
>>  Cats, no less liquid than their shadows, offer no angles to the wind.
>>
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>>     
>
>
>   


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