Related Documentation
- M, PTX, T Series
- Configuring Per-Packet Load Balancing
- Configuring Load Balancing Based on MAC Addresses
- M, MX, PTX, T Series
- Configuring Load Balancing Based on MPLS Labels on DPC I-Chip-Based Hardware
- M, MX, T Series
- Configuring Load Balancing for Ethernet Pseudowires
- M, MX Series
- Configuring VPLS Load Balancing Based on IP and MPLS Information
- Configuring VPLS Load Balancing on MX Series 3D Universal Edge Routers
Overview of Per-Packet Load Balancing
By default, when there are multiple equal-cost paths to the same destination for the active route, the Junos OS 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 configure the Junos OS so that, for the active route, all next-hop addresses for a destination are installed in the forwarding table. This feature is called per-packet load balancing. You can use load balancing to spread traffic across multiple paths between routers. The behavior of the load-balance per-packet function depends on the version of the Internet Processor application-specific integrated circuit (ASIC) in your routing platform:
- On routing platforms with the Internet Processor ASIC, when per-packet load balancing is configured, traffic between routers with multiple paths is spread using the hash algorithm across the available interfaces. The forwarding table balances the traffic headed to a destination, transmitting it in round-robin fashion among the multiple next hops (up to a maximum of eight equal-cost load-balanced paths). The traffic is load-balanced on a per-packet basis.
- On routing platforms with the Internet Processor II ASIC, when per-packet load balancing is configured, traffic between routers with multiple paths is divided into individual traffic flows (up to a maximum of 16 equal-cost load-balanced paths). Packets for each individual flow are kept on a single interface.
- On some platforms, you can increase the number of paths by using the chassis maximum-ecmp statement. With this statement, you can change the maximum number of equal-cost load-balanced paths to 32 or 64.
Related Documentation
- M, PTX, T Series
- Configuring Per-Packet Load Balancing
- Configuring Load Balancing Based on MAC Addresses
- M, MX, PTX, T Series
- Configuring Load Balancing Based on MPLS Labels on DPC I-Chip-Based Hardware
- M, MX, T Series
- Configuring Load Balancing for Ethernet Pseudowires
- M, MX Series
- Configuring VPLS Load Balancing Based on IP and MPLS Information
- Configuring VPLS Load Balancing on MX Series 3D Universal Edge Routers
Published: 2013-02-01
Related Documentation
- M, PTX, T Series
- Configuring Per-Packet Load Balancing
- Configuring Load Balancing Based on MAC Addresses
- M, MX, PTX, T Series
- Configuring Load Balancing Based on MPLS Labels on DPC I-Chip-Based Hardware
- M, MX, T Series
- Configuring Load Balancing for Ethernet Pseudowires
- M, MX Series
- Configuring VPLS Load Balancing Based on IP and MPLS Information
- Configuring VPLS Load Balancing on MX Series 3D Universal Edge Routers
