The following table lists the cases in which LDP LSR ECMP hashing occurs when an MPLS encapsulated packet is received at LSR, and the cases where the MAC or IP packet address fields that are used in hashing vary.
Number and types of labels egressing iLER |
Packet header address fields used in hashing1 |
Hashing scenario2 |
Notes |
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|---|---|---|---|---|---|
Varying MAC |
Varying IP |
Hashing over LAG at LSR |
Hashing over ECMP paths at LSR |
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2 (LDP transport label and service label) |
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— |
✓ |
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✓ |
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✓ |
✓ |
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3 (LDP transport label, service label, and hash label) |
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The last label egressing the iLER is a hash label, which has a different value from the other two (2) labels because it has different MAC and IP fields in the packet of the service traffic. |
✓ |
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✓ |
✓ |
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✓ |
✓ |
✓ |
||
✓ |
✓ |
✓ |
✓ |
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3 (LDP/RSVP transport label, BGP3107 label, and service label) |
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The packet egressess the LSR between the PE and ASBR with three (3) labels. Each label has the same value in every stream for traffic forwarded in a specific service. However, the values are not the same for traffic forwarded in multiple services using the same LDP LSP. |
✓ |
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✓ |
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✓ |
✓ |
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4 (LDP/RSVP transport label, BGP 3107 label, service label, and hash label) |
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The packet egressess the LSR between the PE and ASBR with three (3) labels and one (1) hash label, which is the fourth label in the packet. Hashing does not occur at the LSR between the PE and ASBR; however, if a LAG is configured on egress of the ASBR, the packets are hashed over the LAG members. |
✓ |
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✓ |
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✓ |
✓ |
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