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How Do NE40Es/NE80Es/NE5000Es Implement LSP Load Balancing?

Publication Date:  2013-01-07 Views:  64 Downloads:  0
Issue Description

How do NE40Es/NE80Es/NE5000Es implement LSP load balancing?

Handling Process


Root Cause


When traffic reaches an NE40E/NE80E/NE5000E, there are multiple public equal-cost routes available to the same destination. In this case, multiple corresponding equal-cost LDP LSPs are generated. This implementation is the same as the implementation of a non-Huawei router.

When a Huawei router functions as a PE, the PE attaches an inner VPN label to the MPLS packets that come from a CE. After the MPLS packets are labeled, the PE searches the outer MPLS label value using the inner VPN label value. Currently, the default implementation of a Huawei router is that traffic is forwarded only on one public network LSP even though there are multiple equal-cost LSPs. Namely, load balancing is not performed. To implement load balancing, add the following configurations on the PE:

Create a tunnel policy and specify the number of LSPs that are to participate in load balancing using the following command.

tunnel  select-seq  lsp  load-balance-number X

Apply the tunnel policy in the VPN view.

X in the preceding command indicates the number of LSPs that are to participate in load balancing. The value ranges from 1 to 6. A maximum of six LSPs can be used for load balancing.

But V6R1 and after version the X is 32.

For example, there are three equal-cost LSPs destined for a single destination. If the preceding configurations are not added, the PE selects one of the public network LSPs over which to forward the traffic coming from the CE instead of load balancing the traffic to all three equal-cost LSPs. If the tunnel select-seq lsp load-balance-number 2 command is configured on the PE, the PE selects two of the three equal-cost LSPs for load balancing and hashes the traffic to the selected LSPs using a hash algorithm with the quintuple information as the hash key. The quintuple information includes the protocol type, source and destination IP addresses, source and destination port numbers. If the tunnel select-seq lsp load-balance-number 3 command is configured on the PE, the PE selects all the LSPs to forward the traffic in load balancing mode.

When a Huawei router functions as a P, the P forwards MPLS packets based on the outer MPLS label value, without considering the inner VPN label. Therefore, the public network LSPs automatically participate in load balancing