Cisco ACI understanding

[Amit Kulshrestha]

Dear All,

I am getting into new project of cisco ACI implementation to built fresh DC.Being a beginner in ACI, although having good experience of tradition networking.I am going through all possible installation & deployment guide. I have few queries which you all expert people in ACI can answer:-

1- There is way shown how to configure DNS/NTP/SNMP in ACI. In my case DC is fresh , that means 1 has to built DNS/NTP/SNMP server, which would be having IP, that IP would be having some gateway (vlan's IP),which then should be configured on some L3 switch.

Will that L3 switch should not be part of ACI fabric or where that L3 switch will be placed in network ?
how that L3 switch will communicate and connect with ACI?.

2- Having more worked on tradition network, i am finding difficulty to designing IP schema in terms of DB/Server/OoB/L3Out.
i would be very grateful if any of you is having done in there previous project, can share that. Remove anything or change it to any fake valve which you do not want in terms of customer privacy. I only want to have idea.

3- How do is design BD(Bridge Domain)?

4- Can i have multiple tenant in my DC. ? Or is standard way ?

5- Vrf- What is use of Vrf in ACI?

6- What will happen if we do not create Vrf in ACI ?

Regards
Amit

[Waruna Rasanga]

1. In this scenario, are these servers connecting to the ACI leaf switches or to the L3 switch itself?

a. If servers are connecting to the ACI leaf switches and the gateway of those servers are in the external L3 switch.

You have to connect the L3 switch to the ACI and extend the VLANs (EPGs in ACI) toward L3 switch as L2 (Just extend the VLAN toward switch). And assign those VLANs (EPGs) in the server connected ports as well.

Then establish the connection between APIC OOB IP range and DNS/NTP/SNMP IP range base on your network design. (Through FW or Core switch)

Note: the BD of those EPGs are L2. (No need to define subnet in ACI).

b. If servers are connected to the L3 switch itself

You only need to do is establish connectivity between APIC OOB IP range and DNS/NTP/SNMP IP range base on your network design. (Through FW or Core switch).

2. In this case you can have different subnet for DB/Server/OOB. Base on your host requirement choose a subnet mask. For L3Outs, when we are creating SVI you will only need /29 subnet to have peering with another router. So, you can decide IPs base on that.

3. You can have 1 BD for 1 IP segment.

For example: in your network, you have 3 different subnets for APP, WEB and DB you can have 3 BD for those subnets.

This is based on your network design.

4. Yes, you can have multiple tenants in the DC

5 .VRF is a unique L3 forwarding plane which will allow you to use same IP range in different VRFs

6. You cannot create EPGs in ACI without having an VRF. So there should be at least 1 VRF in the fabric

Hope this would clarify your queries.

Thanks

Waruna