3Com 10014298 manual Setting Flow Control for Ethernet Port, Set Flow Control for Ethernet Port

38CHAPTER 2: PORT CONFIGURATION

Setting Flow Control for Ethernet Port

If congestion occurs in the local switch after enabling flow control in both the local and the peer switch, then the switch will inform its peer to pause sending packets. Once the peer switch receives this message, it will pause packet sending, and vice versa. In this way, packet loss is effectively reduced. The flow control function of the Ethernet port can be enabled or disabled through the following command.

Perform the following configuration in Ethernet port view.

Table 31 Set Flow Control for Ethernet Port

Operation	Command
Enable Ethernet port flow control	flow-control
Disable Ethernet port flow control	undo flow-control

By default, Ethernet port flow control is disabled.

Permitting/Forbidding Jumbo Frames on the Ethernet port

Using the jumbo frame enable command, you can allow jumbo frames (1523 to to 9216 bytes) to pass through the specified Ethernet port. Note that packets up to 1522 bytes, including the IEEE 802.1Q tagging are always allowed to pass through Ethernet ports.

Jumbo frames are only allowed for Ethernet Type II frames. Most network equipment, including NICs, switches, and routers are not capable of supporting jumbo frames and will always discard these packets.

Perform the following configuration in Ethernet port view.

Table 32 Permitting/Forbidding Jumbo Frame to Pass Through the Ethernet Port

Operation	Command
Permit jumbo frame to pass through the	jumboframe enable [
Ethernet port.	jumboframe_value ]
Forbid jumbo frame to pass through the	undo jumboframe enable
Ethernet port.

By default, jumbo frames are disabled.

Setting Ethernet Port Broadcast Suppression Ratio

You can use the following commands to restrict the broadcast traffic. Once the broadcast traffic exceeds the value set by the user, the system maintains an appropriate broadcast packet ratio by discarding the overflow traffic. This is done to suppress broadcast storm, avoid suggestion, and ensure the normal service.

The parameter is taken the maximum wire speed ratio of the broadcast traffic allowed on the port. The smaller the ratio is, the less broadcast traffic is allowed. If the ratio is 100%, do not perform broadcast storm suppression on the port.