25.c) ACI Multi-Pod-Part 3 - LEARN WORK IT
25.c) ACI Multi-Pod-Part 3 - LEARN WORK IT
25.c) ACI Multi-Pod-Part 3 - LEARN WORK IT
Multi-Pod
Configuration
Follow these steps to con�gure a Multi-Pod
solution with multiple APICs:
Example Topology
Con�guration:
Con�guring multicast
Follow these guidelines for con�guring multicast on the
IPN switch:
● Bidirectional Protocol-Independent Multicast (Bidir
PIM) for Broadcast, Unknown Unicast, and Multicast
(BUM) traf�c between pods must be supported.
◦ IPN device must support Bidir PIM for a range of at
least /15.
◦ Because of this requirement, all �rst-generation N9Ks
are not supported IPN devices because the Broadcom
T2/T2+ ASICs only support a maximum Bidir PIM range
of /24. The N9Ks will let you con�gure larger ranges for
Bidir PIM but it will not work as expected.
● The multicast Rendezvous Point (RP) must be de�ned.
● The same loopback address needs to be con�gured on
each IPN switch to be used for the static rendezvous
point address.
Bidir PIM does not support the concept of an anycast
rendezvous point like traditional PIM Sparse Mode
(PIM-SM) Any-Source Multicast (ASM). Bidir PIM
redundancy is based on a backup model or phantom
rendezvous points. In other words, a single rendezvous
point handles everything, and in the case of a failure,
another rendezvous point takes over. This model is
achieved by con�guring different subnet masks on
these loopback addresses for each IPN switch, which
allows the use of the longest-pre�x-match logic in the
routing process.
Bidir PIM is used for many-to-many communication
and uses only the shared tree for traf�c distribution.
Shared trees handle the distribution of multicast data
traf�c from the rendezvous point to the receivers and
use a mechanism for the sources called the Designated
Forwarder (DF). The designated forwarder decides
which packets need to be forwarded upstream to the
rendezvous point. The designated forwarder is elected
by all the PIM neighbors in a subnet advertising their
unicast routes to the rendezvous point, with the router
with the best route being elected. With bidir PIM, the
same shared tree is used for traf�c to be sent from the
rendezvous point to receivers and from the sources to
the rendezvous point. Thus, sources can also be
receivers, and vice-versa, leading to bidirectional
branches within the shared tree.
N o t e : The spine nodes generating and receiving BUM
traf�c act like multicast sources and receivers.
Con�guration: