IBM3229P2035
Advance
IBM Packet Routing Switch Serial Interface Converter
Figure 4: Bit and Byte Notation
UTOPIA Level 3 Bit/Byte Notation
MSB
LSB
7
7
0
7
0
7
0
0
7
Byte 0
Byte 1
Byte 2
Byte 3
IBM 28.4 G Packet Routing Switch/DASL Bit/Byte Notation
MSB
0
LSB
7
0
0
7
0
7
Byte 0
Byte 1
Byte 2
Byte 3
The ingress block is the receive path between the protocol engine device (PE) and the rest of the converter
logic. The egress block is the transmit path between the converter transmit logic and the PE.
The timing on the UTOPIA-3 interface is the same for out of band flow control (OBFC) and for in band flow
control (IBFC) modes except when operating in IBFC mode, the UTOPIA-3 flow control (RXENB at ingress
and TXFULL at egress) is not normally used, as the packet header carries all the required information.
However if a PE performs an interface level flow control (OBFC), those interface leads can be used for that
purpose. In IBFC, fill-up (idle) packets flow through the interface to maintain a continuous stream of flow
control information.
3.1 Data Interface Between IBM Packet Routing Switch Serial Interface Converter and
Protocol Engine
UTOPIA-3 bit/byte notation is used throughout the protocol engine (PE) interface description. After the byte
formatting (which reshuffles the byte position to match the IBM 28.4G Packet Routing Switch (switch) DASL
interface), the switch DASL bit/byte notation is used.
3.2 Functional Overview
The IBM Packet Routing Switch Serial Interface Converter (the converter) ingress and egress interfaces are
consistent with a subset of the UTOPIA-3 specifications:
• Single PHY interface mode (connection between one converter and one protocol engine)
• Typical operating clock range is 100 - 111 MHz to match the IBM 28.4 G Packet Routing Switch clock rate
(up to 111 MHz), but an interface clock rate as low as 50 MHz is supported
• Only 32-bit data paths
• Packet format is 64 - 80 bytes (programmed in the converter at configuration time)
• Only packet level handshake mode (use of signals RXPAV in Receive Path and TXPAV in Transmit Path)
prssi.02.fm
Functional Description
Page 19 of 154
March 1, 2001
IBM [ IBM ]
