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CHAPTER 2: SIGNAL DESCRIPTIONS
Gigabit Ethernet (GMII) Configuration
Gigabit Ethernet Media Independent Interface (GMII) is configured in one of two ways:
• 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-3e NP.
• Use two CP clusters for wire-speed performance and additional processing power. You
can implement up to two Gigabit Ethernet ports per C-3e NP.
Table 10 lists the possible CP cluster combinations you can use and Figure 4 shows receive
and transmit pin configurations by cluster. Table 11 lists the signals and pinouts for
Gigabit Ethernet (GMII).
Table 10 Transmit and Receive Pin Combinations for Gigabit Ethernet and Fibre Channel
CLUSTER
SINGLE CLUSTER MODE (TBI OR GMII)
Port 1 Tx and Rx
TWO CLUSTER MODE (GMII)*
Port 1 Tx
0
1
Port 2 Tx and Rx
Port 1 Rx
*
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.
Figure 4 GMII/TBI Transmit and Receive Pin Configurations
Single Cluster Mode
Pin Configuration
Two Cluster Mode
Pin Configuration
Tx
Tx
Rx
Cluster
0
Cluster
0
}
}
Port 1
Port 2
Rx
nc
Port 1
Tx
nc
Tx
Rx
}
Cluster
1
Cluster
1
Rx
Cluster
2
Cluster
2
NOTE: Cluster 2 & 3 are Internal Loopback Only.
NOTE: Cluster 2 & 3 are Internal Loopback Only.
Cluster
3
Cluster
3
nc = not connected
C3EN
FREESCALE [ Freescale ]
