Xilinx 1000BASE-X - Manual (Page 226)

226 www.xilinx.com Ethernet 1000BASE-X PCS/PMA or SGMII v9.1
UG155 March 24, 2008
Appendix E: Rx Elastic Buffer Specifications R
Maximum Frame Sizes for Sustained Frame Reception
Sustained frame reception refers to the maximum size of frames which can be
continuously received when each frame is separated by a minimum interframe gap.
The size of frames that can be reliably received is dependent on the two considerations
previously introduced in this appendix:
•
The size of the Elastic Buffer, see “Rx Elastic Buffers: Depths and Maximum Frame
Sizes”
•
The number of clock correction characters present in a minimum interframe gap, (see
“Clock Correction” )
Table E-3 summarizes the maximum frame sizes for sustained frame reception when used
with the different Rx Elastic Buffers provided with the core. All frame sizes are provided in
bytes.
Jumbo Frame Reception
A jumbo frame is an Ethernet frame which is deliberately larger than the maximum sized
Ethernet frame allowed in the IEEE 802.3 specification. The size of jumbo frames that can
be reliably received is identical to the frame sizes defined in
“Maximum Frame Sizes for
Sustained Frame Reception,” page 226 .
Table E-3: Maximum Frame Size: (Sustained Frame Reception) Capabilities of the Rx Elastic Buffers
Ethernet Standard and
Speed
Rx Elastic Buffer Type
TBI RocketIO SGMII Fabric Buffer
1000BASE-X (1 Gbps) 20000 (limited by clock
correction) 20000 (limited by clock
correction) 20000 (limited by clock
correction)
SGMII 1 Gbps 20000 (limited by clock
correction) 20000 (limited by clock
correction) 20000 (limited by clock
correction)
SGMII 100 Mbps 20000 (limited by clock
correction) 9000 (limited by buffer
size) 20000 (limited by clock
correction)
SGMII 10 Mbps 2800 (limited by buffer
size) 900 (limited by buffer
size) 2800 (limited by buffer
size)