Virtual Port Channels And Multicast; Maximum Transmission Unit Limitation; Multicasting With Both F Series And M Series Modules In A Chassis; General Multicast Restrictions - Cisco Nexus 7000 Series Configuration Manual

Dynamic Shared Memory support in MRIB/M6RIB for VDC
Dynamic Shared Memory support in MRIB/M6RIB for VDC
The MRIB and M6RIB maintain independent route information for each virtual routing and forwarding (VRF)
instance in a virtual device context (VDC). VDC resource templates set the minimum and maximum limits
for the shared memory when you create a VDC. The Cisco NX-OS software reserves the minimum limit for
the resource to the VDC. Any resources allocated to the VDC beyond the minimum are based on the maximum
limit and availability on the device. VDC templates set limits on both IPv4 multicast route memory and IPv6
multicast route memory. You can change the VDC resource limits by applying a new VDC resource template.
Changes to the limits take effect immediately except for the IPv4 and IPv6 route memory limits, which take
effect after the next VDC reset, physical device reload, or physical device stateful switchover. A switchover
occurs when the active route processor (RP) fails, is removed from the networking device, or is manually
taken down for maintenance.
Instead of a static allocation of the entire configured memory for the multicast routes, the shared memory for
MRIB/M6RIB dynamically adds up or is removed based on the increase or decrease, respectively, in the
number of routes, without making any modifications to the VDC.
The dynamic shared memory in MRIB/M6RIB is not affected during synchronization of the active and standby
processors and during a physical device stateful switchover from the active to the standby processor.

Virtual Port Channels and Multicast

A virtual port channel (vPC) allows a single device to use a port channel across two upstream switches. When
you configure a vPC, the following multicast features may be affected:
• PIM and PIM6—Cisco NX-OS software for the Nexus 7000 Series devices does not support PIM SSM
• GMP snooping—You should configure the vPC peers identically.

Maximum Transmission Unit Limitation

On the Cisco NX-OS software for the Nexus 7000 Series devices, the Maximum Transmission Unit (MTU)
for a given mroute is equal to the smallest MTU of the OIF. Packets exceeding that MTU value are dropped
and not multicast routed to any of the OIFs for that mroute.

Multicasting with both F Series and M Series Modules in a Chassis

Beginning with Cisco NX-OS Release 5.1, you can add an F Series module, which is a Layer 2-only module,
into the Cisco Nexus 7000 Series chassis. When you add this module to a chassis that already contains M
Series modules, you can provision multicasting.

General Multicast Restrictions

Cisco NX-OS multicast features have the following restrictions:
• Cisco Nexus 7000 Series devices do not support Pragmatic General Multicast (PGM).
Cisco Nexus 7000 Series NX-OS Multicast Routing Configuration Guide
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or Bidr on a vPC.
Overview