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ACI TCAM Exhaustion

sentenced
Level 1
Level 1

Dear Community!

 

I need to know what happens when TCAM is exhausted in a Leaf (usually it goes to software for processing - intensifying CPU usage), but what happens in ACI? 

 

Looking forward to a reply. Any supporting document would be a plus! 

1 Accepted Solution

Accepted Solutions

gmonroy
Cisco Employee
Cisco Employee

sentenced,

    I'm not sure about CPU per box, but what we have seen is that if you cap your TCAM per leaf, subsequent programmings will fail. Given that contract programmings occur in batches, it will fail in chunks. This means that if you are un-prepared or unaware of hitting some TCAM limit, you will find that traffic between EPGs may be dropping due to policy (hitting the implicit deny) since none of the allow rules have been programmed.

 

Additional Info on Contracts and TCAM usage:

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/1-x/ACI_Best_Practices/b_ACI_Best_Practices/b_ACI_Best_Practices_chapter_010.html

 

Additional Info on programming verification:

https://www.cisco.com/c/en/us/support/docs/cloud-systems-management/application-policy-infrastructure-controller-apic/119023-technote-apic-00.html

 

-Gabriel

View solution in original post

2 Replies 2

gmonroy
Cisco Employee
Cisco Employee

sentenced,

    I'm not sure about CPU per box, but what we have seen is that if you cap your TCAM per leaf, subsequent programmings will fail. Given that contract programmings occur in batches, it will fail in chunks. This means that if you are un-prepared or unaware of hitting some TCAM limit, you will find that traffic between EPGs may be dropping due to policy (hitting the implicit deny) since none of the allow rules have been programmed.

 

Additional Info on Contracts and TCAM usage:

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/1-x/ACI_Best_Practices/b_ACI_Best_Practices/b_ACI_Best_Practices_chapter_010.html

 

Additional Info on programming verification:

https://www.cisco.com/c/en/us/support/docs/cloud-systems-management/application-policy-infrastructure-controller-apic/119023-technote-apic-00.html

 

-Gabriel

Thank you dude! Much appreciated!

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