Tier-0 Tier-1 communication down in an NSX-T 2.4.0 environment
Article ID: 324226
Updated On:
Products
VMware NSX Networking
Issue/Introduction
Symptoms:
The following criteria are all met
The following criteria are all met
- NSX-T 2.4.0 environment
- The T0-T1 transit subnet is non default and is part of the 169.254.0.0/16 range
- T1 connected networks are not visible on the active Edge T0 DR vrf when running "get forwarding"
- T0 DR and T1 DR LinkedPort interfaces show no IPv4 address configured, only IPv6 e.g.
Edge1(vrf)> get int
Interface : 98147703-a33d-4023-9d34-558832bdc09c
Ifuid : 307
Name : LinkedPort_T0
Mode : lif
IP/Mask : fe80::50:56ff:fe56:4455/64;fc66:c650:9440:e800::2/64
MAC : 02:50:56:56:44:55
VNI : 71683
LS port : dcf2124f-a792-4bb1-946f-c05e6d9b5b46
Urpf-mode : NONE
Admin : up
Op_state : up
MTU : 1500
Interface : 98147703-a33d-4023-9d34-558832bdc09c
Ifuid : 307
Name : LinkedPort_T0
Mode : lif
IP/Mask : fe80::50:56ff:fe56:4455/64;fc66:c650:9440:e800::2/64
MAC : 02:50:56:56:44:55
VNI : 71683
LS port : dcf2124f-a792-4bb1-946f-c05e6d9b5b46
Urpf-mode : NONE
Admin : up
Op_state : up
MTU : 1500
Environment
VMware NSX-T Data Center 2.x
VMware NSX-T Data Center
VMware NSX-T Data Center
Cause
NSX-T 2.4.0 introduced support for IPv6.
This code change involved new handling of interfaces with link local addresses.
IPv4 link local subnet is 169.254.0.0/16.
Any transit subnet interface in the range 169.254.0.0/16 will be removed and not readded preventing communication between the T0 and T1 routers.
This issue is not present in earlier releases and can impact upgraded or newly installed environments.
This code change involved new handling of interfaces with link local addresses.
IPv4 link local subnet is 169.254.0.0/16.
Any transit subnet interface in the range 169.254.0.0/16 will be removed and not readded preventing communication between the T0 and T1 routers.
This issue is not present in earlier releases and can impact upgraded or newly installed environments.
Resolution
This is a known issue affecting NSX-T Datacenter 2.4.0. There is currently no resolution.
Workaround:
The T0-T1 transit subnet must be re-configured to use a different subnet which is not part of 169.254.0.0/16.
The subnet is sepcified on the T0 router. To make the change the T1 routers must be detached from the T0. Once the change is complete the T1 routers can be readded.
Workaround:
The T0-T1 transit subnet must be re-configured to use a different subnet which is not part of 169.254.0.0/16.
The subnet is sepcified on the T0 router. To make the change the T1 routers must be detached from the T0. Once the change is complete the T1 routers can be readded.
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