RE: [802.3ae] PMA Loopback
> -----Original Message-----
> From: Tim Warland [mailto:twarland@xxxxxxxxxxxxxxxxxx]
> Sent: Tuesday, December 04, 2001 6:50 AM
> To: Burt Christian
> Cc: HSSG (E-mail)
> Subject: Re: [802.3ae] PMA Loopback
> Burt Christian wrote:
> > Hi,
> > According to the PMA loopback definition in [126.96.36.199.2] and [51.8],
> > the PMA shall accept data on the transmit path and return it on the
> > receive path.
> > Another useful PMA loopback mode would be one where the input
> > from the PMD service interface would be retimed and returned on
> > the transmit path.
> > Is this mode defined ? If not, why not ?
> This mode is not defined due to the complexity involved.
> 10GE is defined as two asynchronous data paths - one in the
> transmit direction and one in the receive direction. The two
> paths operate at approximately 10.3125 or 9.95328 for LAN
> and WAN mode respectively. The only thing we know about
> the frequency of operation (at the PMA) is that Tx and Rx will
> be within 200ppm (120ppm for WAN mode).
According to table 51-8, transmit source clock specifications for
fPMA_TXCLK_SRC are +/-100 ppm (or 200 ppm, if you like) for 10GBASE-R
and +/-20 ppm (or 40 ppm) for 10GBASE-W. And according to table 51-12,
receiver clock specifications for fPMA_RX_CLK are +/-100 ppm for both
10GBASE-R and 10GBASE-W.
I am trying to understand why you mentioned 120ppm for 10GBASE-W ?
Burt S, Christian.
Tel : (613)599-5797
Fax : (613)599-1247