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Date: Tue, 22 Jul 1997 03:10:40 -0500 (CDT)
From: "Jo, SanKu" <skjo@jumprun.tamu.edu>
To: freebsd-multimedia@freebsd.org
cc: freebsd-hackers@freebsd.org
Subject:  VIF : the bandwidth taken by multicasting packet
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Howdy !
 
Because I hope to check the Bandwidth taken by the IP
multicastingrouter(FreeBSD box),
I tried to use iotcl(Channel_descriptor, SIOCGETVIFCNT, struct
*sioc_vif_req).
I heard this function retruns the input and output Bandwidth.
There are two cases for testing.
 
1. When Host-A is source and Host-B is receiver, the Bandwidth rate value
   returned  by the function  is correct.
 
2. When Host-B is source and Host-A is receiver, the Bandwidth rate
value(out_bytes)
   retruned by the function is wrong.
   Even the case witout any receiver in Backbone(as Host-A), the function
   returns the whole bandwidth rate(in_bytes) which is taken by the
source, HOST-B.
   I think the prune function is all right. 
 
 
Below is my configuration with multicast routers denoted
by asterisks:
======++=====BackBOne                <--in
      ||                              -->out
      || HOST-A                       VIF        Research Subnet  HOST-B
------++----------           ---------------------   ||       ----------
|sparc*          | ethernet  |   freebsd 2.1  *  |   ||       |sparc   |
| 128.194.169.93 |-----------|169.53       166.4 |---++-------| 166.5  |
|       3.8      |           |          3.3      |   ||       |        |
------------------           ---------------------   ||       ----------
                                                          Its' default
gateway is freebsd
 
How can I get correct bandwidth for the second case ?
Is it possible or not to get it ?
 
And where can I get some information for hacking the multicasting function
in FreeBSD ?
 
Any comment will be very appreciated.
 
Thank you for your kind attention !
 
Best regards,
Jo, SanKu
 
Texas A&M University.
Http://ee.tamu.edu/~skjo