ACI MultiPod IPN using C9500

[packet2020]

Hi All,

Is it possible to use a Catalyst 9500 switch as an IPN for ACI MultiPod? 

The Catalyst 9500 17.6 VLAN configuration guide states that this is not supported, however I think that this is only applicable for non high-performance switches as high performance switches such as the C9500-48Y4C and C9500-32C support subinterfaces without any major restrictions.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/17-6/configuration_guide/vlan/b_176_vlan_9500_cg/configuring_vlan_trunks.html 

"Because subinterfaces are not supported on Cisco Catalyst 9500 Series Switches, these cannot be used as an Application Centric Infrastructure (ACI) Interpod Network (IPN) device. You also cannot use a switch virtual interface (SVI) because Interpod spine switches reuse the same MAC address; which causes flapping of MAC address in the IPN Layer 2 network"

The Catalyst 9500s also support the following features so I'm assuming that high performance switches will work and will be supported as IPNs?

Multicast
PIM BIDIR
DHCP Relay
OSPF
Increased MTU
Layer 3 sub-interfaces
QOS considerations

[Flavio Miranda]

Hello

 I think your question is valid but I dont believe so.

Cisco Nexus ACI-Mode Switches Hardware Support Matrix

https://www.cisco.com/c/dam/en/us/td/docs/Website/datacenter/acihwsupport/index.html

You only see Nexus as candidate.

This link here is not Cisco but also states that it is not possible

https://learnduty.com/forum/can-you-use-cisco-catalyst-9500-with-aci/

[packet2020]

Hi Flavio,

Thanks for the response, however the links that you provided above relate to the switches within the ACI fabric (spine and leaf switches). My question relates to the IPN switches that will provide connectivity between pods within a Multi-Pod solution.

Interestingly the ACI Multi-Pod whitepaper states the below. The C9500 high performance switches support the listed requirements so in theory these should be supported. 

"Another typical question is whether specific network devices should be deployed as IPN routers. The simple answer is that any device that can fulfill the requirements listed in the following paragraphs is perfectly suited for performing the IPN duties. However, the recommendation is to deploy, when possible, switches of the Cisco Nexus® 9200 family or switches of Cisco Nexus 9300 second-generation (or older) family (i.e., EX models or newer), as they are the ones most commonly found in production and also the ones more frequently validated in Cisco internal testing."

[Robert Burns · Accepted solution]

Yes, you can use C9500 as IPN.  That doc you references is outdated.  Starting in IOS-XE 16.10.1 support for L3 Sub Interfaces was added.  I believe there was also some improvements to Phantom RP support which is required for PIM BiDir - which was added around 17.4 I believe.  So as long as your Cat 9500s are running that verison or later, you're good to go.

Robert

[packet2020]

Thanks Robert, appreciated. 

[nkhawaja1]

In17.4 phantom RP is not supported. but 17.5 doesn't have this statement.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/17-4/configuration_guide/ip_mcast_rtng/b_174_ip_mcast_rtng_9500_cg/configuring_pim.html#r_restrictions_bidirectional_pim

Restrictions for Bidirectional PIM

Phantom rendezvous point (RP) is not supported.

Is there any sample configuration for C9500? I tried to build the following configuration but I have not tested it. can you please review this:

Standard IP access list pim-group
10 permit 225.0.0.0, wildcard bits 0.0.0.255
20 permit 239.0.0.0, wildcard bits 0.0.0.255
!
Standard IP access list ssm-range
10 permit 232.0.0.0, wildcard bits 0.0.0.255
!
ip pim bidir-enable
!
ip pim rp-address AA.BB.CC.DD pim-group
ip pim ssm range ssm-range
!