Multicast Routing Table Size; Faster Convergence With The Prebuilt Source Tree - Cisco Nexus 5000 Series Operation Manual
Release 5.0(3)n2(1) cisco nexus 5000 series switches, cisco nexus 2000 series fabric extenders
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- Cli configuration manual (660 pages) ,
- Configuration manual (334 pages) ,
- Command reference manual (196 pages)
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Faster Convergence with the Prebuilt Source Tree
S e n d d o c u m e n t a t i o n c o m m e n t s t o n 5 k d o c f e e d b a c k @ c i s c o . c o m
Note
Multicast forwarding in this topology does not work.
Multicast Routing Table Size
When you enable a vPC on a Nexus 5500 Platform switch, one multicast route (*,G) or (S,G) requires
two entries in the routing table; therefore, the multicast routing table size is half the size of what is
supported in topologies where vPC is not enabled.
Beginning with Cisco NX-OS Release 5.0(3)N1(1b), the Cisco Nexus 5500 Platform multicast routing
table size is 2000 entries in non-vPC topologies and 1000 entries in vPC topologies.
Faster Convergence with the Prebuilt Source Tree
In a non-vPC topology, only the designated router (DR) can join the source tree. In a vPC topology, when
a receiver is connected to a Cisco Nexus 5500 Platform switch or Fabric Extender (FEX) via vPC, both
peer switches initiate a PIM (S,G) join toward the source DR. In a topology where both vPC peer
switches have equal costs to the source, the vPC primary switch wins the assert and forwards multicast
traffic for receivers connected to the Nexus 5500 Platform switch or FEX using the vPC. The vPC
secondary switch also joins the source tree and pulls the multicast data. To prevent data duplication, the
vPC secondary switch drops the data due to an empty outgoing interface (OIF) list. Once the vPC
secondary switch detects the failure of the vPC primary switch, it adds the receiver VLAN to the OIF
list and starts to forward the multicast traffic immediately. Because the vPC secondary switch joins the
source tree before the failure, it does not need to initiate the (S,G) join and waits for the tree to be built.
As a result, it improves the convergence time in the case of a failure with the active multicast traffic
forwarder.
Figure 2-9
(RP) are in the Layer 3 network. N5k-2, which is the VPC primary switch, is the multicast traffic
forwarder for receivers in VLAN 10.
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
2-10
shows one receiver that is connected to a dual-homed FEX. The source and Rendezvous Point
Chapter 2
Cisco Nexus 5500 Platform Layer 3 and vPC Operations
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