Inter-rack RP Pairing
In a multi chassis (MC) system, the active-standby RP pairing in a single rack is called intra-rack pairing. There is a possibility that the rack which houses the active VM and standby VM may go down. This results in the reboot of all the line card chassis, thus impacting traffic of the MC system. Inter-rack (or cross-rack) pairing allows pairing route processors (RP) between racks to provide high availability (HA) against rack failures. The RP of one rack is paired with the RP on the next rack. The pairing is determined by the SDR manager through a daisy chain algorithm. The algorithm is executed only on the discovered set of nodes. The pairing remains consistent as long as the set of nodes that were discovered is constant.
Only the racks with dual RPs (an RP on both slots of the rack) are considered for inter-rack pairing. The pairing algorithm is triggered automatically when:
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a rack is inserted
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a change in chassis configuration is committed
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RP is re-inserted (or replaced)
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re-pair command is manually executed
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change in configuration between inter-rack and intra-rack pairing, and vice-versa
Inter-rack pairing is triggered manually or automatically, when:
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an RP is added or deleted
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an OIR is performed for an RP