Technical Documentation

Configuring Load Balancing Using Hash Key (NSM Procedure)

When there are multiple equal-cost paths to the same destination for the active route, the JUNOS software uses a hash algorithm to choose one of the next-hop addresses to install in the forwarding table. Whenever the set of next hops for a destination changes in any way, the next-hop address is rechosen using the hash algorithm.

You can select which packet header data to use for per-flow load balancing using the hash-key option.

To configure load balancing 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 Forwarding Options > Hash Key.
  4. Add or modify settings as specified in Table 1.
  5. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 1: Load Balance Configuration Details

Task Your Action

Configure layer information for the load-balancing specification. Only the IPv4 protocol is supported.

  1. Click Inet next to Family.
  2. Click Layer 3 next to Inet.
  3. In the Comment box, enter the comment.
  4. Select the Destination Address check box to include the destination-address MAC information in the hash key.
  5. Click Layer 4 next to Inet.
  6. In the Comment box, enter the comment.

Configure load balancing based on MPLS labels. Only the IPv4 protocol is supported.

  1. Click Mpls next to Family.
  2. Expand Mpls.
  3. Click Payload next to Mpls.
  4. In the Comment box, enter the comment.
  5. Click Ip next to Payload.
  6. In the Comment box, enter the comment.
  7. Expand Ip.
  8. Click Layer 3 Only next to Ip.
  9. Select layer-3-only to include only Layer 3 IP information.
  10. Select port-data to include the source and destination port field information.
    1. In the Comment box, enter the comment.
    2. Select Source Msb to Include the most significant byte of the source port.
    3. Select Source Lsb to Include the least significant byte of the source port.
    4. Select Destination Msb to include the most significant byte of the destination port.
    5. Select Destination Lsb to Include the least significant byte of the destination port.

Configure load balancing based on Layer 2 media access control information.

  1. Click Multiservice next to Mpls.
  2. In the Comment box, enter the comment.
  3. Select Source Mac to include the source-address MAC information in the hash key.
  4. Select Destination Mac to include the destination-address MAC information in the hash key.

Published: 2009-08-23