Technical Documentation

Configuring Layer 2 Address Learning and Forwarding Properties (NSM Procedure)

On MX Series routers only, you can configure Layer 2 address learning and forwarding properties in support of Layer 2 bridging. The router learns unicast media access control (MAC) addresses to avoid flooding the packets to all the ports in a bridge domain. The router creates a source MAC entry in its source and destination MAC tables for each MAC address learned from packets received on ports that belong to the bridge domain.

To configure Layer 2 address learning in NSM:

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the configuration tree, expand Protocols > L2 Learning.
  4. Add or modify settings as specified in Table 1.
  5. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 1: L2 Learning Configuration Details

Task Your Action

Configure Layer 2 address learning and forwarding properties globally.

  1. In the Comment box, enter the comment.
  2. From the Global Mac Table Aging Time list, select the time elapsed before MAC table entries are timed out and entries are deleted.

    Range : 10 through 1000000

  3. Select one of the following:
    • Global No Mac Learning—To disable MAC learning for the entire router
    • Global Mac Statistics—To enable MAC accounting for the entire router.

Limit the number of media access control (MAC) addresses learned from the logical interfaces on the router.

  1. Click Global Mac Limit next to L2 Learning.
  2. In the Comment box, enter the comment.
  3. From the Mac Limit list, select the Number of MAC addresses that can be learned systemwide.

    Range: 20 through 1,048,575

  4. From the Packet Action list, select drop to specify that packets for new source MAC addresses be dropped after the MAC address limit is reached.

Published: 2009-08-23