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Antonio Macia
Participant

Spines in remote POD not getting IPs

Hi, 

We are deploying a second POD in a remote location. IPN network and IPN devices are configured and exchanging OSPF routes successfully. From the remote POD IPN device we can ping the apic's infra IP. The problem is with the spines not receiving any IP address during the first time discovery. 

 

We can see the DHCP discovery packets reaching the IPN interface but for some reason the IPN is not forwarding them. The IPN sub-interfaces are in VLAN 4 and the spines are directly connected to them. The only explanation I can imagine is that the spines are not tagging the DHCP discovers with the VLAN4. Do the spines tag the traffic by default? We cleared the configuration and they run factory-defaults. Is there any previous step?

 

Our IPN devices are Catalyst 6509 and the interfaces are configured with the ip helper-address command pointing to the apic's infra IPs.

 

Thanks.

2 REPLIES 2
Sergiu.Daniluk
VIP Engager

I am not a Cat 6k expert so I will just ask: does Cat 6500 support DHCP relay on subinterfaces? That is something you might want to check. How did you verified that DHCP packets are not forwarded by IPN?

If you see packets reaching the IPN router, but not being forwarded, then is either a routing problem or a DHCP relay problem. Since you mentioned that ping is working, then the only thing left is DHCP relay ^_^

 

 

Stay safe

Sergiu

llsanchez
Beginner

Hi,

have you toke this limitation into account?

 

"Because subinterfaces are not supported on Cisco Catalyst 9500 Series Switches, these cannot be used as an Application Centric Infrastructure (ACI) Interpod Network (IPN) device. You also cannot use a switch virtual interface (SVI) because Interpod spine switches reuse the same MAC address; which causes flapping of MAC address in the IPN Layer 2 network."

 

The documentation is from C9500, but the C6500 behaves into the same way.

 

Information gathered from

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/16-10/configuration_guide/vlan/b_1610_vlan_9500_cg/configuring_vlan_trunks.html#reference_189D3E81C3C44BA489A65D6CD8F0C996

 

Regards

 

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