Nokia 7705 SAR-W Series - ECMP Support; Figure 29 ECMP Support

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5.2.5.3 ECMP Support
In Figure 29, the leaf discovers ROOT-1 from all three ASBRs (ASBR-3, ASBR-4 and
ASBR-5).
Figure 29 ECMP Support
The leaf chooses which ASBR will be used for the multicast stream using the
following process.
1. The leaf determines the number of ASBRs that should be part of the hash
calculation.
The number of ASBRs that are part of the hash calculation comes from the
ECMP value (configured with the config>router>ecmp command). For
example, if the ECMP value is set to 2, only two of the ASBRs will be part of the
hash algorithm selection.
2. After selecting the upstream ASBR, the leaf determines whether there are
multiple equal cost paths between it and the chosen ASBR.
- If there are multiple ECMP paths between the leaf and the ASBR, the leaf
performs another ECMP selection based on the configured ECMP value.
This is a recursive ECMP lookup.
- The first lookup chooses the ASBR and the second lookup chooses the path
to that ASBR.
For example, if ASBR 5 was chosen in Figure 29, there are three paths between
the leaf and ASBR-5. A second ECMP decision is therefore made to choose the
path.
sw1300
IGP, iBGP, mLDP eBGP, mLDP IGP, iBGP, mLDP
Join S1, G1
S1, G1
10.60.3.2, 192.0.2.60
PE-2
(LEAF)
10.0.0.8
ASBR-3
10.0.0.21
ASBR-1
10.0.0.2
PE-1
(ROOT-1)
10.0.0.14
SAR Core AS3 SAR Core AS1
Host
Source
VPRN-1
RD 60:60
ASBR-2
10.0.0.20
ASBR-5
10.0.0.23
ASBR-4
10.0.0.22
VPRN-1
RD 600:600