External TEP Pool Multi-Pod

[Fernando Hernández]

Do you guys know if the External TEP Pool when configuring Multi-Pod is only used for Spines, or it assigns IPs to Leafs as well?

I´m going to configure Multi-Pod and need to decide what prefix to use for the External TEP Pool. Can I use a /27 if I will have no more than 10 Spines? (But if it assigns to Leafs as well, I would need definteley a /24).

Why not just using a /24? Cause need to save addressing. We dont have now much space left, so I was thinking on using a /27 for each POD.

I would appreciate your help

[Sergiu.Daniluk · Accepted solution]

Hi @Fernando Hernández

The external TEP pool is used for creating the control-plain loopbacks on the spines used for establishing MP-BGP EVPN adjacencies across pods, plus the anycast IP addresses for each pod (anycast-mac, anycast-v4 and anycast-v6).

Basically for a POD with 2 spines you will have:

2x EVPN RID - one for each spine

1x ETEP - shared by both spines

1x anycast-mac, 1x anycast-v4, 1x anycast-v6 - shared by both spines

Total number: 4x IP shared + # of spines = 6x IP

But I am curious, why do you want to save the addressing space when anyway the IPN should be in a separate VRF, and the External TEP is only used for IPN (there is no reason why not to be), so basically you can go wild with the address space.

Anyway, good luck with the planning.

Cheers,

Sergiu

[Robert Burns]

Agreed with Sergiu.  FYI - The recommended range for the eTEP subnet is between a /22 & /29.

Robert

[Fernando Hernández]

Excellent. That was really helpful to understand how many IPs are used.

And yeah, thats true. I didnt remember that they are going to be part of the VRF so they shouldn´t go outside to production.

Thanks for the help! Was really great.