Multipod Provisioning and DHCP

[Luke Poskitt]

Hi All,

Apologies if this is a very simple question, however after reading through the ACI Multipod deployment guide and white paper I can't seem to find any definitive answer.

When configuring the IPN for a Multipod deployment, should the DHCP relay address be the ooband management interface of the APIC(s) in the seed POD, the infrastructure VLAN/TEP IP address of the APIC(s) (e.g. the IP address of bond0.<infrastructure VLAN>), or something else entirely?

From what I can ascertain from examples, it would seem to be the latter, however I can't seem to find any information regarding assignment of the APIC TEP IP address from the TEP pool and whether it remains consistent (e.g. first available IP address in TEP range).

Cheers,

-Luke

[Luke Poskitt]

Probably bad form to post a reply to myself, but using the APIC TEP IP worked and appears to be the correct configuration.

Is it correct to assume that APICs will always be assigned the first available addresses (e.g. .1 .2) in the TEP pool?

[Robert Burns]

APICs will ALWAYS take the first 3 sequential addresses in the Initial TEP pool setup during install.  Only the Nodes will pull TEP address from their respective PODs TEP Range.  APICs always pull from the same one, regardless of their POD location.

Robert

[Luke Poskitt]

Thanks for the fast response and detailed answers guys - great stuff.

One last question - a little off-topic - is anyone able to provide me in the direction of further information regarding the BGP extended community name required when creating a Multi-Pod deployment? 

All documentation seems to suggest that this must be 'extended:as2-nn4:5:16', however I haven't been able to find much documentation that thoroughly describes the format or values used (could just be my weak Google-fu).

[Tomas de Leon]

Luke,

I apologize in advance that I am not a BGP or OSPF wizard.  At this time (as you mentioned) you must configure  'extended:as2-nn4:5:16' for the community for Multipod.

The Multipod connection profile is critical to the multipod route distribution for endpoint routes, multicast routes, and wan/services routes.  We use BGP & OSPF for this process between the ACI Pods, Spines and the IPN Gateway.

To ensure that this communication is reliable and consistent with performance and operations, I would make some assumptions that the development team tested and QA'd a set of configuration parameters that would work under the condiditions needed for Multipod setups.

In addition, since this is a private network between pods, consistency for multipod configurations helps the Cisco TAC and the Development teams troubleshoot possible issues.

I hope this helps.

T.

[Robert Burns]

Yeah you're on the right track.  The Relay is for the Infra IP of the "other" APICs on each side of the IPN. 

Let's say you have

Site1:

apic1-10.0.0.1

apic2-10.0.0.2

Site 2:

apic3-10.0.0.3

Site1 IPN would relay to 10.0.0.3

Site2 IPN would reluay to 10.0.0.1 & 10.0.0.2

(Some people just add all APIC addresses oneach side for simplicity, but its not necessary).

As you guessed its to support the Infra TEP IPs that get allocated for Switch Nodes, VPCs, AVS etc which are all infra VLAN addresses.

Robert