
C-Port Confidential
Preliminary Version — January 21, 2002
Pin Descriptions Grouped by Function
27
Gigabit Ethernet (GMII) Configuration
Gigabit Ethernet Media Independent Interface (GMII) is configured in one of two ways:
1 Use one CP cluster when density is more important than wire-speed performance
because you can then implement up to four Gigabit Ethernet ports per C-5 NP.
2 Use two CP clusters for wire-speed performance and additional processing power. You
can implement up to two Gigabit Ethernet ports per C-5 NP.
Table 7 lists the possible CP cluster combinations you can use and
Figure 3 shows receive
and transmit pin configurations by cluster.
Table 8 lists the signals and pinouts for Gigabit
Ethernet (GMII).
Table 6 10/100 Ethernet Signals
Signal Name* Pin #
Total
Type
I/O
Label
Signal Description
CPn_0
1
LVTTL
O
REF_CLK
Transmit and Receive Clock (50MHz)
CPn_1
1
LVTTL
I
CRS_DV
Carrier Sense (CRS)/ Receive Data Valid (RX_DV). CRS indicates that
traffic is on the link, and is asserted if the signal is a 1 or an
alternating 1010... RX_DV indicates that a receive frame is in
progress and the data present on the RXD pins is valid. It is
asserted if this signal is a 1 for more than one cycle.
CPn_2
1
LVTTL
O
TXD(0)
Transmit Data 0 (first on wire)
CPn_3
1
LVTTL
O
TXD(1)
Transmit Data 1 (second on wire)
CPn_4
1
LVTTL
I
RXD(0)
Receive Data 0 (first on wire)
CPn_5
1
LVTTL
I
RXD(1)
Receive Data 1 (second on wire)
CPn_6
1
LVTTL
O
TX_EN
Transmit Enable. When asserted, the data on TXD is encoded and
transmitted on the twisted pair cable.
Total Pins
7
* n can be from 0 to 15. See Table 4. Table 7 Transmit and Receive Pin Combinations for Gigabit Ethernet and Fibre Channel
Cluster
Single Cluster Mode (TBI or GMII)
Two Cluster Mode (GMII)*
* The Two Cluster Mode column lists typical configurations. Any cluster can be set up to either receive
or transmit. So you could configure a dual cluster mode where cluster 0 receives and cluster 3
transmits.
0
Port 1 Tx and Rx
Port 1 Tx
1
Port 2 Tx and Rx
Port 1 Rx
2
Port 3 Tx and Rx
Port 2 Tx
3
Port 4 Tx and Rx
Port 2 Rx