Hi @Ibrahim Jamil
First, allow me to recommend some ciscolive presentations which I strongly suggest starting with if you plan on learning ACI:
1. Introduction to ACI - BRKACI-1000
2. Your first 7 days of ACI - BRKACI-1001
3. ACI for Network Engineers - BRKACI-1002
4. Mastering ACI Forwarding Behavior – A day in the life of packet - BRKACI-3545
List can go on and on, but these breakout sessions are really good.
Go over these ones, and you will be able to answer most of your questions related to "how ACI works".
Now back to your questions:
1)How is BD different from VLAN?
BD is the L2 forwarding construct within the fabric, but if you are familiar with VXLAN, basically a BD is a broadcast/multicast domain, assigned to a L2VNI so it can span multiple switches, but has NO relationship to the original VLAN tag.
2)Can an EPG point towards more than one Bride Domain
Nope. EPG-BD relationship is many-to-one. Many EPGs can link to the same BD, but each EPG can link to only one BD
3)What is need to have more than one Bridge domain in same VRF?
Because you want to separate the forwarding (broadcast) domains. Same thing happens in traditional networking as well, when creating vlans.
4)Why is there need to configure Route Reflector?
RR is required to exchange external routes/prefixes (routes learned from L3Out) from border leaf switches to compute leaf switches, through the use of BGP VPNv4.
5)What are 2 types of tables found on Leaf Nodes?
This is an odd one. I am not sure what tables are you looking for. There are a looooot of tables on leaf switches:
endpoint table, zoning-rule table, arp table (for L3out only), routing table etc
Anyway, check out the CL videos. It will help you a lot in understanding Cisco ACI.
Stay safe,
Sergiu
