Wired Intelligent Edge (Campus Switching and Routing)

Requirement:

How is L4-Based trunk load balancing enabled?

The Trunk Load Balancing using L4 ports allows the use of TCP/UDP source and destination port number for trunk load balancing. This is in addition to the current use of source and destination IP address and MAC addresses. Configuration of Layer 4 load balancing would apply to all trunks on the switch. Only non-fragmented packets will have their TCP/UDP port number used by load balancing. This insures that all frames associated with a fragmented IP packet are sent through the same trunk on the same physical link.

The priority for using Layer 4 packets when this feature is enabled is as follows:

1. If the packet protocol is an IP packet and has Layer 4 port information, use Layer 4.

2. If the packet protocol is an IP packet and does not have Layer 4 information, use Layer 3 information.

3. If the packet is not an IP packet, use Layer 2 information.

Syntax:

trunk-load-balance <L3-based | L4-based> 

When the L4-based option is configured, enables load balancing based on Layer 4 information if it is present. If it is not present, Layer 3 information is used if present; if Layer 3 information is not present, Layer 2 information is used. The configuration is executed in global configuration context and applies to the entire switch.

Default: L3-based load balancing 
<L3-based>: Load balance on Layer 3 information if present, or Layer 2 information. 
<L4-based>: Load balance on Layer 4 port information if present, or Layer 3 if present, or Layer 2. 

Rack2sw1# show trunk 

 Load Balancing Method: L3-based (Default), L2-based if non-IP traffic 

  Port | Name                             Type      | Group  Type 
  ---- + -------------------------------- --------- + ------ -------- 
  L1   |                                  SFP+DA1   | Trk12  Trunk 
  L2   |                                  SFP+DA1   | Trk12  Trunk 

Rack2sw1(config)# trunk-load-balance l4-based 

Rack2sw1# show trunk 

 Load Balancing Method: L4-based, L2-based if non-IP traffic 

  Port | Name                             Type      | Group  Type 
  ---- + -------------------------------- --------- + ------ -------- 
  L1   |                                  SFP+DA1   | Trk12  Trunk 
  L2   |                                  SFP+DA1   | Trk12  Trunk