Bridge--using Packet Capture Library(libpcap.a) -- efficiency ?????

From: kamal kc (rosey_kc_at_yahoo.com)
Date: 10/31/04

  • Next message: Robert Watson: "Re: Bridge--using Packet Capture Library(libpcap.a) -- efficiency ?????" 
    Date: Sun, 31 Oct 2004 01:27:04 -0700 (PDT)
To: freebsd-net@freebsd.org

    I have made a bridge using the Packet Capture Library
    I set the two nics to promiscous mode and transfer packet
    between the two packet capture handles
    A piece of the code I use for initializing the packet capture device descriptor---
    .....
    pcap_t *pd;
    pd = (pcap_t *)malloc(sizeof(*pd));
     if (pd == NULL) {
      printf("memory allocation error");
     }
     if((pd=pcap_open_live(device,BUFFSIZE,1,0,errbuf))==NULL)
      {printf("pcap_open_live: %s",errbuf);
       exit(1);
      };
     v = 1;
     if (ioctl(pd->fd, BIOCIMMEDIATE, &v) < 0) {
      printf("can't set BIOCIMMEDIATE");
      exit(1);
      }
    ..................
    Now the problem is efficiency !!!
    The RTT for a ping packet to traverse across the bridge takes a fastest of about 3ms when
    run as normal process
    and about 2ms when run as daemon. But when setting
    gateway_enable="YES"
    in rc.conf the RTT is less than 1 ms. (i.e. FreeBSD Box acting as bridge)
    I have FreeBSD 5.1 BOX.
    I used Packet Capture Library(libpcap.a) because I could find of none libraries in capturing packets that
    could return with the ethernet header. Further I could not find good usage maunal on BPF.
    In the above code setting the TIMEOUT value to 0 also didn't improve the time taken to
    capture and transmit the packets across the network.
    Each packet is processed by a separate thread that is envoked by the main thread listening on
    the packet capture handle.
    ++++++++++++++++
    So finally
    Could anyone suggest a way on improving the time delay and making the bridge process packets faster
    with improved response time.
    Solutions using Packet Capture Library would be great !!
    Thanks in advance
    Kamal
    ++++++++++++++++++++

                    
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  • Next message: Robert Watson: "Re: Bridge--using Packet Capture Library(libpcap.a) -- efficiency ?????"