dual-dr
Syntax
dual-dr {
enhanced;
}Hierarchy Level
[edit dynamic-profiles name protocols pim interface],
[edit logical-systems name protocols pim interface],
[edit logical-systems name routing-instances name protocols pim interface],
[edit logical-systems name tenants name routing-instances name protocols pim interface],
[edit protocols pim interface],
[edit routing-instances name protocols pim interface],
[edit tenants name routing-instances name protocols pim interface]
Description
Enable PIM dual designated router mode for a pair of Multichassis Link Aggregation Group (MC-LAG) peers managing VLAN multicast traffic and Layer 3 multicast traffic over IRB interfaces.
PIM dual designated router mode sets up one device in a pair of MC-LAG peers as a primary designated router (DR) and the other device as a standby or backup DR for redundancy in managing multicast packet forwarding. Both devices join the multicast forwarding tree and receive multicast traffic. If the primary device fails, the standby quickly takes over forwarding multicast packets with minimal traffic disruption.
In the default or backwards-compatible dual designated router mode (no
enhanced option specified), both DRs forward packets for a short
time while negotiating which device will forward the multicast traffic. After PIM
forwarder negotiation, only one device continues to forward traffic. If the primary DR
fails, the standby can take over forwarding multicast packets upon detecting the
failure. When the primary DR comes back online and is receiving multicast traffic again,
it resumes forwarding and invokes PIM forwarder negotiation again to reduce duplicate
packet load.
In enhanced dual designated router mode (enhanced option specified),
both the primary and standby DRs receive multicast traffic, but only the primary DR
forwards the packets, skipping PIM forwarder negotiation. Upon primary DR failure, the
standby takes over forwarding immediately, and also switches to primary role. When the
prior primary DR comes back online, it assumes the standby role, receiving but not
forwarding multicast traffic. The new primary DR continues forwarding multicast packets
without any traffic interruption, and again no duplicate packet traffic is
generated.
If you want to enable dual designated router mode, we recommend using the
enhanced option, if available, to achieve optimal convergence time
in resuming multicast traffic flow both when a DR fails and when it comes back online
again.
Options
| none |
Enable default dual designated router mode (available for backwards compatibility). |
| enhanced |
Enable enhanced PIM dual designated router mode (recommended if available). |
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.
Release Information
Statement introduced in Junos OS Release 13.2X51 for the QFX Series.
Statement introduced in Junos OS Release 16.1 for the MX Series.
Statement with enhanced option introduced in Junos OS Release 17.2R1 for Junos Fusion Data Center.