Hi.

On 21 fév, 06:21, query.c...@gmail.com wrote:
> Hi ,
>
> I am one of the members who is managing a Wide Area Network . The
> Backbone speed of
> this network is around 1.4 gbps and the links that connect to
> this backbone are of 10 mpbs
> and 100mpbs speed .
> I am managing a LAN which connects to the above WAN with a 10mbs
> link. Some other
> sites are connected with 100 mbps link . Now to gain better
> performance , some TCP
> tuning had to be done at the Host level. So , I was trying to
> calculate the size of the TCP
> window (Bandwidth Delay Product ) which is given by
>
> BDP = bandwidth * round trip time.
>
> My Doubt is regarding this formula . For bandwidth , which bandwidth
> I should consider, the
> speed of host's NIC (100 mbps), or the speed of the link (10 mbps )
> which connects us
> to the WAN or the speed of the Backbone (1.4 gbps).

You are right for the window size. But don't forget the window size is
limited to 65535 (16 bits), Unless
you initiate TCP/IP connections with the "window scale option" which
can set window size up to 32 bits.
See RFC 1323.

--
michel marcon aka cmic, SysAdmin
>
> And for Round Trip Time , I communicate with different links with
> different RTT . e.g With
> one link the RTT is 26.678 ms and with another is 67.786 mps. So
> which RTT should I
> consider.
>
> Please somebody help me out in understanding the formula correctly.