Overlapping External TEP IPs on loopbacks within a Multi-Pod

Danny Koenig · ‎07-23-2025

Hi guys,

within my Multi-Pod (2 Pods) environment I got an overlapping IP which belongs to the external TEP-Pool from Pod 2. This fabric is not in production yet.

Informations:

external TEP-Pool Pod 2: 172.20.12.0/24
Data Plane IP: 172.20.12.1
Spine 221 IP: 172.20.12.2
Spine 222 IP: 172.20.12.3

Fault F1425 raised:

# fault.Inst
code             : F1425
ack              : no
alert            : no
annotation       :
cause            : ip-provisioning-failed
changeSet        : ipv4CfgFailedBmp (New: ipv4:Addraddr_failed_flag,ipv4:Addrctrl_failed_flag,ipv4:AddrlcOwn_failed_flag,ipv4:AddrmodTs_failed_flag,ipv4:AddrmonPolDn_failed_flag,ipv4:Addrpref_failed_flag,ipv4:Addrtag_failed_flag,ipv4:Addrtype_failed_flag,ipv4:AddrvpcPeer_failed_flag), ipv4CfgState (New: 1), operStQual (New: subnet-overlap)
childAction      :
created          : 2025-07-23T18:13:28.259+02:00
delegated        : no
descr            : IPv4 address(172.20.12.2/32) is operationally down, reason:Subnet overlap on                          node 221                           fabric hostname ZDITBSW221-SP
dn               : topology/pod-2/node-221/sys/ipv4/inst/dom-overlay-1/if-[lo6]/addr-[172.20.12.2/32]/fault-F1425
domain           : access
extMngdBy        : undefined
highestSeverity  : major
lastTransition   : 2025-07-23T18:15:30.654+02:00
lc               : raised
modTs            : never
occur            : 1
origSeverity     : major
prevSeverity     : major
rn               : fault-F1425
rule             : ipv4-addr-oper-st-down
severity         : major
status           :
subject          : oper-state-err
title            :
type             : operational
uid              :
userdom          : all

Loopback Interfaces on Spines

Spine 221:

lo0                  172.24.164.66/32     protocol-up/link-up/admin-up
lo1                  172.20.12.1/32       protocol-up/link-up/admin-up
lo2                  172.20.12.2/32       protocol-up/link-up/admin-up
lo3                  172.24.0.64/32       protocol-up/link-up/admin-up
lo4                  172.20.12.229/32     protocol-up/link-up/admin-up
lo5                  172.20.12.230/32     protocol-up/link-up/admin-up
lo7                  172.24.128.33/32     protocol-up/link-up/admin-up
lo8                  172.24.128.34/32     protocol-up/link-up/admin-up
lo9                  172.24.128.35/32     protocol-up/link-up/admin-up
lo10                 172.24.0.66/32       protocol-up/link-up/admin-up
lo11                 172.24.192.70/32     protocol-up/link-up/admin-up
lo12                 172.24.0.65/32       protocol-up/link-up/admin-up
lo13                 172.24.192.69/32     protocol-up/link-up/admin-up
lo14                 172.24.192.71/32     protocol-up/link-up/admin-up

Spine 222:

lo0                  172.24.164.64/32     protocol-up/link-up/admin-up
lo1                  172.20.12.1/32       protocol-up/link-up/admin-up
lo2                  172.20.12.3/32       protocol-up/link-up/admin-up
lo3                  172.24.0.64/32       protocol-up/link-up/admin-up
lo4                  172.20.12.229/32     protocol-up/link-up/admin-up
lo5                  172.20.12.230/32     protocol-up/link-up/admin-up
lo6                  172.20.12.2/32       protocol-up/link-up/admin-up
lo7                  172.24.128.33/32     protocol-up/link-up/admin-up
lo8                  172.24.128.34/32     protocol-up/link-up/admin-up
lo9                  172.24.128.35/32     protocol-up/link-up/admin-up
lo10                 172.24.0.65/32       protocol-up/link-up/admin-up
lo11                 172.24.192.65/32     protocol-up/link-up/admin-up
lo12                 172.24.0.66/32       protocol-up/link-up/admin-up
lo13                 172.24.192.66/32     protocol-up/link-up/admin-up
lo14                 172.24.192.67/32     protocol-up/link-up/admin-up

Output from the APIC (moquery -c ipv4Addr):

# ipv4.Addr
addr             : 172.20.12.2/32
childAction      :
ctrl             :
dn               : topology/pod-2/node-221/sys/ipv4/inst/dom-overlay-1/if-[lo2]/addr-[172.20.12.2/32]
ipv4CfgFailedBmp :
ipv4CfgFailedTs  : 00:00:00:00.000
ipv4CfgState     : 0
lcOwn            : local
modTs            : 2025-07-23T18:13:29.721+02:00
monPolDn         :
operSt           : up
operStQual       : up
pref             : 0
rn               : addr-[172.20.12.2/32]
status           :
tag              : 0
type             : primary
vpcPeer          : 0.0.0.0



# ipv4.Addr
addr             : 172.20.12.2/32
childAction      :
ctrl             :
dn               : topology/pod-2/node-221/sys/ipv4/inst/dom-overlay-1/if-[lo6]/addr-[172.20.12.2/32]
ipv4CfgFailedBmp : ipv4:Addraddr_failed_flag,ipv4:Addrctrl_failed_flag,ipv4:AddrlcOwn_failed_flag,ipv4:AddrmodTs_failed_flag,ipv4:AddrmonPolDn_failed_flag,ipv4:Addrpref_failed_flag,ipv4:Addrtag_failed_flag,ipv4:Addrtype_failed_flag,ipv4:AddrvpcPeer_failed_flag
ipv4CfgFailedTs  : 00:00:00:00.000
ipv4CfgState     : 1
lcOwn            : local
modTs            : 2025-07-23T18:13:27.150+02:00
monPolDn         : uni/fabric/monfab-default
operSt           : down
operStQual       : subnet-overlap
pref             : 0
rn               : addr-[172.20.12.2/32]
status           :
tag              : 0
type             : primary
vpcPeer          : 0.0.0.0



# ipv4.Addr
addr             : 172.20.12.2/32
childAction      :
ctrl             :
dn               : topology/pod-2/node-222/sys/ipv4/inst/dom-overlay-1/if-[lo6]/addr-[172.20.12.2/32]
ipv4CfgFailedBmp :
ipv4CfgFailedTs  : 00:00:00:00.000
ipv4CfgState     : 0
lcOwn            : local
modTs            : 2025-07-23T18:13:25.032+02:00
monPolDn         : uni/fabric/monfab-default
operSt           : up
operStQual       : up
pref             : 0
rn               : addr-[172.20.12.2/32]
status           :
tag              : 0
type             : primary
vpcPeer          : 0.0.0.0

How can this be fixed? Found no hint.

Thank you very much!

Cheers,

Danny

Danny Koenig · ‎07-24-2025

Workaround: Assigning another IP from ext. TEP-Pool, error will be cleared. But 172.20.12.2 is still in use.

How to clean this up and as the IP concept says?

Hefe2 · ‎07-28-2025

Actually had the same problem after upgrading to 6.1(2g) and also assigned a different IP to one of the spines