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IPG rate estimation for XGENIE




All,

I have examined the IPG bandwidth for the XGENIE approach. 
This is to answer some of the XGENIE issues (2a,2b) raised by Mr. Paul 
Bottorff farsightedly.  
http://grouper.ieee.org/groups/802/3/10G_study/email/msg02127.html

Note that my current position is on (3); using LAN-PHY + XGENIE as the 
WAN-PHY alternative to the ELTE, and the SONET side of the ELTE is the 
Uni-PHY (64b/66b on SONET).  Here we will use the SONET-compatible 
XGENIE ordered-set for end-end OAM&P, instead of its loose relaying 
to the SONET path overhead bytes shown in my previous PDF file.
http://grouper.ieee.org/groups/802/3/10G_study/email/pdf00009.pdf

As has been pointed out by Mr. Roy Bynum repeatedly, our approach 
shoud pay 3% tax for 64b/66b on SONET.  I believe this is worth 
wasting since this approach has the following advantages;

  a) any work done on 64b/66b for the LAN is leveraged.
     (single packet delineation mechanism in 802.3ae)
  b) future-proof for providing non-SONET dark-fiber solution that 
     will be connected seamlessly with LAN-only PHY.  It will provide
     full 10Gb/s MAC rate instead of 9.58464 Gb/s.
  c) XGENIE approach allows both serial PHY and CWDM PHY to be WAN-PHY.

It would be appreciated if someone could confirm the following estimation 
for the IPG bandwidth to be valid or have some mis-understanding.

Best Regards,
Osamu

(1) LAN-PHY with XGENIE, without Open Loop Control*.

                             *Mr. Shimon Muller's Albuquerque proposal
http://grouper.ieee.org/groups/802/3/ae/public/mar00/muller_1_0300.pdf

              |<-------------------- 125us -------------------------->|

10.00000 Gb/s |<-------------------- 156,250 bytes ------------------>|
              [001_1530][12][002_1530][12]......[12][101_1530][12][508bytes
                       IPG#1         IPG#2                   IPG#101

              Assuming that each IPG is /A/K/R/ and we can replace a 
              half of /R/ by XGENIE /O/, we can transmit 50 ordered 
              sets per 125 us.  This is enough to carry 30 overhead 
              bytes defined for full-SONET compatibility.

              If we consider 'JUMBO frame', full-SONET-compatible 
              XGENIE would be difficult to be guaranteed.  However
              we still have enough space to carry B1,J0, B3, G1.
              
              e.g.  8kB Jumbo frame reduces the IPG rate to one fifth,
                    and hence guarantees only 10 ordered set per 125 us.

(2) LAN-PHY with XGENIE, with Open Loop Control to 9.58 Gb/s MAC rate.
    Later the Ethernet frame may be accomodated in SONET payload by 
    zero-overhead delineation mechanism such as EOS or SLP.

 9.95328 Gb/s |<-------------------- 155,520 bytes ------------------>|
 9.58464 Gb/s |      <-------->       <-- ...149,760 bytes   <------->|
              [1_640][1_16,640][2_640][2_ .......... ][9_640][9_16,640]
 SONET-frame  [S_OH1][Payload1][S_OH2][Pay . ....    ][L_OH5][Payload9]

Open Loop Control will reduce the MAC rate by 4.1536 %.
This corresponds to increasing the averaged IPG to 67 bytes 
assuming that the maximum-size packets are continuously transmitted.

10.00000 Gb/s |<-------------------- 156,250 bytes ------------------>|
              [001_1530][67][002_1530][67].....[67][097_1530][67][1341bytes
                       IPG#1         IPG#2                  IPG#97

 9.58464 Gb/s |<-------------------- 149,760 bytes ------------------>|
SONET-payload [001_1530][12][002_1530][12]......[12][097_1530][12][186bytes
                       IPG#1         IPG#2                   IPG#97

              Assuming that each IPG is /A/K/R/K/R/..../A/K/R/....and 
              we can replace a half of /R/ by XGENIE /O/, we can 
              transmit 15 ordered sets per IPG, and hence 1,455 ordered 
              sets per 125 us at the 10.3 Gb/s LAN-PHY section.  
              Therefore, we will have no difficulty even with the 
              Jumbo frame.
              
              In the SONET payload, we can not expect the IPG 
              transparency.  Hence we need some OAM&P info relay 
              at ELTE. (Please see my previous PDF picture.)

(3) LAN-PHY with XGENIE with Open Loop Control to 9.29 Gb/s MAC rate.
    Later the Ethernet frame may be accomodated in SONET payload by 
    64b/66b according to Mr. Howard Frazier's Uni-PHY proposal.

 9.95328 Gb/s |<-------------------- 155,520 bytes ------------------>|
 9.58464 Gb/s |      <-------->       <-- ...149,760 bytes   <------->|
 9.29420 Gb/s |      <-------->       <-- ...145,222 bytes   <-------> |
              [1_640][1_16,640][2_640][2_ .......... ][9_640][9_16,640]
 SONET-frame  [S_OH1][Payload1][S_OH2][Pay . ....    ][L_OH5][Payload9]

Open Loop Control will reduce the MAC rate by 7.058 %.
This corresponds to increase the averaged IPG to 117 bytes 
assuming that the maximum-size packets are continuously transmitted.

10.00000 Gb/s |<-------------------- 156,250 bytes ------------------>|
              [01_1530][117][02_1530][117].....[117][94_1530][117][1432bytes
                       IPG#1         IPG#2                  IPG#94

 9.29420 Gb/s |<-------------------- 145,222 bytes ------------------>|
SONET-payload [001_1530][12][002_1530][12]......[12][094_1530][12][274bytes
                       IPG#1         IPG#2                   IPG#94

              Assuming that each IPG is /A/K/R/K/R/..../A/K/R/....and 
              we can replace a half of /R/ by XGENIE /O/, we can 
              transmit 27 ordered sets per IPG, and hence 2,538 ordered 
              sets per 125 us at the 10.3 Gb/s LAN-PHY section.  
              
              In the SONET payload, we will be able to transmit 47 
              ordered sets per 125 us.  This is enough to carry 30 
              overhead bytes defined for full-SONET compatibility.
              
              Moreover, in this case, we may have no difficulties 
              even with the Jumbo frames since the open loop control 
              will assure the wider IPG when we encocunter them.