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New Member

Help Multicast Nexus 7000

Hi,

We are currently migrating from Cisco 6500 switches to Nexus 7000 switches. I need replicate the following multicast configuration on the 6500 switches in the simplest way so Multicast is functioning on the Nexus 7000 switches.

Cisco 6500 configuration.

ip multicast-routing

interface Vlan8

description

ip address 10.128.46.2 255.255.240.0

ip helper-address 10.72.8.73

no ip redirects

ip pim dense-mode

ip route-cache flow

ip cgmp

standby 8 ip 10.128.32.1

standby 8 preempt

Please could some guidance be provided as to how we can enable multicast on the Nexus 7000 switches in the simplest form so this will continue operating.

Thanks

Darren

5 REPLIES
New Member

Help Multicast Nexus 7000

On NX-OS PIM dense-mode is not supported.

You need to migrate to PIM-Sparse-Mode, using the concept of PIM Rendezvous Points

For a brief introduction to Multicast Concept:

www.ciscolivevirtual.com BRKMPL-1261 - IP Multicast – Concepts, Design and Troubleshooting

Also

http://docwiki.cisco.com/wiki/Cisco_NX-OS/IOS_Multicast_Comparison

Just a brief config conversion the configuration on N7K (using auto-rp):

feature pim

feature interface-vlan

feature dhcp ! for DHCP-Relay / Helper Address

feature hsrp

service dhcp

ip dhcp relay

interface Vlan8

ip address 10.128.46.2 255.255.240.0

no ip redirects

ip pim sparse-mode ! enable PIM Sparse-Mode on interface

ip dhcp relay address 10.72.8.73

hsrp 8

ip 10.128.32.1

preempt

int loopback 100

description interface used for RP Address

ip add

ip pim sparse-mode ! enable PIM Sparse-Mode on interface

ip pim auto-rp rp-candidate loopback100 group-list 224.0.0.0/4

ip pim auto-rp mapping-agent loopback100

ip pim auto-rp forward listen

The "ip pim auto-rp forward listen" must be configured also on others N7k in your Multicast domain.

New Member

Help Multicast Nexus 7000

Hi,

Thanks very much for your reply this could be a life saver. Our access switches which are combination of Cisco4507RE and Cisco 3750 switches connect to the Nexus switches via layer 2 trunks. Do we need to consider any multicasdt configuration on these. Currently there isn't any.

Many Thanks

Darren 

New Member

Help Multicast Nexus 7000

If the 4507RE and the 3750 are configured as Layer 3 switching you need to configure ip multicast routing also on them with ip pim sparse-mode under layer 3 interfaces (SVI or Routed interfaces). Otherwise igmp snooping is already active and you don't need any further configuration.

New Member

Help Multicast Nexus 7000

Hi,

Just one final question. Am I ok to configure a secondary RP on my secondary Nexus? Am I correct in thinking  the system elects the device with the highest mapping-agent IP address?

Thanks

int loopback 100

description interface used for RP Address

ip add

ip pim sparse-mode ! enable PIM Sparse-Mode on interface

ip pim auto-rp rp-candidate loopback100 group-list 224.0.0.0/4

ip pim auto-rp mapping-agent loopback100

ip pim auto-rp forward listen

New Member

Help Multicast Nexus 7000

The highest candidate RP address is elected as RP for each group or range advertised.

Anyway I suggest to configure two (or more) Nexus 7k devices with the "PIM Anycast-RP" feature.

You can configure the Loopback100 on both devices with the same IP (f.i. 1.1.1.1 on N7k-1 and 1.1.1.1 on N7k-2), this is the RP address then the two devices communicate each other using another loopback IP .

In this manner you get fast convergence when a PIM Rendezvous Point (RP) router fails.

For further information rfc4610 - Anycast-RP using Protocol Independent Multicast (PIM) http://www.ietf.org/rfc/rfc4610.txt

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