MAC-Learning with Delay - ACI

[netbeginner]

Hello All, 

I m Here with some new observations. 

We have a 02 locations with Single PoD streched fabric ACI. having a observation on MAC address learning with some delay.

Setup is like : 

Location-1 :

We have 6500 Switch connected with Dual leg , One with  ACI Leaf-103 and and other with ACI leaf-104 via vPC.

Location-2 :

We have other 6500 switch connected with Dual leg, One with  ACI Leaf-203 and and other with ACI leaf-204 via vPC.

We are forming a transit path (L2) for OSPF neighbor ship between those 02 , 6500 switches. Eg

Location-1 6500 Switch :

Vlan10

IP : 10.10.10.1/30

OSPF enabled

Location-2 6500 Switch:

Vlan10

IP: 10.10.10.2/30

OSPF enabled

We observed that for respective EPG (for VLAN10) at APIC end under EPG(10) -> Operational -> Client End Points..MAC of 10.10.10.1 and 10.10.10.2 are learning with delay and ping not working initial for some time due to which OSPF neigborship not coming up. ping is taking approx 50-60 secs to work and then only we are seeing the MAC for both locations under EPG. Thinking...Why we are not getting immediate ping response , why this is taking time to learn MAC.

Probably , this may be the genuine or default behaviour which we did'nt noticed earlier. But now observed during some Troubleshooting.like to understand the logic.

point to mention here is : We are selecting Deployment Immediacy (under EPG10) for static port binding for 6500 switch vpC as "On Demand" . Will this be anyhow is the cause of delay in MAC learning. What if we select "Immediate" in Deployment Immediacy. Will that help us anyway. Just checking for all opinion.

Rgds

[Sergiu.Daniluk · Accepted solution]

Hello @netbeginner 

Changing the deployment immediacy to immediate might improve the timing, but since we talk about communication inside a single EPG, not sure how much will change. Still you can try it. Basically this is the meaning of it:

Once the policies are downloaded to the leaf software, deployment immediacy can specify when the policy is pushed into the hardware policy content-addressable memory (CAM).

• Immediate—Specifies that the policy is programmed in the hardware policy CAM as soon as the policy is downloaded in the leaf software.

• On demand—Specifies that the policy is programmed in the hardware policy CAM only when the first packet is received through the data path. This process helps to optimize the hardware space

Other things which you can try to improve the communication are

L2 Unknown unicast - Flood

ARP Flooding: Checked

Cheers,

Sergiu

[netbeginner]

HI MSD , 

Would there be any disconnection, if we change L2 Unknown unicast from Hardware proxy to Flood.

[Sergiu.Daniluk]

I do not expect any impact on the user traffic for this change.

Cheers,

Sergiu

[netbeginner]

Hi Msd, 

Just for information to all, 

We we changed from hardware proxy to Flood, There was disconnection for few seconds.

Thanks ..