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Configuring the Number of Active Ports on a 16-Port 10-Gigabit Ethernet MPC on MX Series Routers

The JUNOS Software provides the number-of-ports active-ports configuration statement at the [edit chassis fpc slot-number] hierarchy level. This statement can be used for enabling or disabling the physical ports on the Packet Forwarding Engines of a 16-port 10-Gigabit Ethernet MPC (16x10GE 3D MPC). This configuration can be used for the following purposes:

  • Enabling Switch Control Board (SCB) redundancy—For maximum bandwidth capabilities (12-port line-rate bandwidth), the 16x10GE 3D MPC uses all the available SCBs (three SCBs for an MX960 router, two SCBs for an MX480 or MX240 router) actively in the chassis.

    If SCB redundancy (2+1 SCBs on an MX960 router or 1+1 SCB on an MX480 or MX240 router) is required, ports on the line card can be disabled by setting the number of usable ports per line card to 8. In such a case, the third and fourth ports (ports 0/2-3, 1/2-3, 2/2-3, 3/2-3) on every Packet Forwarding Engine are disabled.

  • Ensuring guaranteed bandwidth by preventing oversubscription—The 16x10GE 3D MPC supports one 10-Gigabit Ethernet tunnel interface for each Packet Forwarding Engine. The effective line-rate bandwidth of the MPC is 12 ports because of an oversubscription ratio of 4:3. Therefore, configuring a tunnel interface might further result in the Packet Forwarding Engines being oversubscribed. To prevent such oversubscription and to ensure a guaranteed bandwidth, include the number-of-ports configuration statement to disable one or two ports per Packet Forwarding Engine.

To configure the number of active ports on the MPC, include the number-of-ports active-ports configuration statement at the [edit chassis fpc slot-number] hierarchy level:

[edit chassis fpc slot-number] number-of-ports (8 | 12);

Specify either 8 or 12 ports using this statement. When eight active ports are configured, two ports per Packet Forwarding Engine are disabled, and the LEDs on the MPC are set to yellow. When you specify 12 active ports, one port per Packet Forwarding Engine is disabled and the corresponding LED is set to yellow. When you do not include this statement in the configuration, all 16 default ports on the MPC are active.

  • Committing the configuration after including the number-of-ports active-ports configuration statement brings down the Ethernet interfaces for all the ports on the MPC before the ports configuration becomes active.
  • A minimum of one high-capacity fan tray is necessary for meeting the cooling requirements of the MPC. The JUNOS Software generates a chassis Yellow alarm recommending fan tray upgrade for optimal performance, if the MX router chassis contains an old fan tray.

For more information about the 16x10GE 3D MPC, see the MX Series Line Card Guide.


Published: 2010-04-26

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