H3C Technologies H3C S7500E Series Switches - Manual (Page 19)

1-5
Setting Speed Options for Auto Negotiation on an Ethernet Port
Speed auto negotiation enables an Ethernet port to negotiate with its peer for the highest speed
supported by both ends by default. If the highest speed is not desirable, you can narrow down the
speed option list for negotiation.
Figure 1-1 Speed auto negotiation application scenario
As shown in Figure 1-1 , the network card speed of each server in the server cluster (Server 1, Server 2,
and Server 3) is 1000 Mbps, and the speed of GigabitEthernet 2/0/4, which provides access to the
external network for the server group, is 1000 Mbps too. If you do not specify speed options for auto
negotiation on the switch, the total rate of GigabitEthernet 2/0/1, GigabitEthernet 2/0/2 and
GigabitEthernet 2/0/3 will exceed 1000 Mbps, which may cause congestion on the egress port
GigabitEthernet 2/0/4. To solve the problem, you can set 100 Mbps as the only option available for
speed negotiation on GigabitEthernet 2/0/1, GigabitEthernet 2/0/2, and GigabitEthernet 2/0/3.
Follow these steps to set speed options for auto negotiation on an Ethernet port:
To do… Use the command… Remarks
Enter system view system-view —
Enter Ethernet port view
interface interface-type
interface-number
—
Configure the auto-negotiation
transmission rate range
speed auto [ 10 | 100 | 1000 ] * Optional
This function is available only for 100-Mbps or 1000-Mbps Layer 2 Ethernet ports that support
speed auto negotiation.
The speed and speed auto commands supersede each other, and whichever is configured last
takes effect.