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Date:      Mon, 14 Jul 1997 20:13:57 -0500 (CDT)
From:      Sanku Jo <>
Subject:   VIF : the bandwidth taken by multicasting packet [Question]
Message-ID:  <>

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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   |
| |-----------|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.

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