Posted on March 27, 2019 4:01 pm
 |  Asked by Aftab Siddiqui
 |  132 views
RESOLVED
0
0
Print Friendly, PDF & Email

As per the attached diagram, its a VXLAN EVPN setup. Everything was working fine on that side. Both switches in city A and City B have MLAG configured with the TOR Stack switches. After creating MLAG with the TOR Stack switches, all MAC addresses have started flapping. For example MAC address ab-bc-cd is coming from the server connected to TOR Stack switch in City B. On B-SW01 it is learning from Port-channel10 (MLAG) but on B-SW02 it is learning from VX1 interface (vxlan) which is coming from the RR via B-SW01 and then it hands it back to the TOR Stack switch. When I shut down 1 port on the port-channel towards the TOR Stack switches then it becomes stable. Any clue?

B-SW01 Config:

interface Loopback0
ip address 10.101.1.1/32

interface Vxlan1
vxlan source-interface Loopback0
vxlan udp-port 4789
vxlan vlan 300 vni 300300

Router bgp 1234
vlan 300
rd 10.101.1.1:300
route-target both 300:300
redistribute learned

#show mac address-table vlan 300
300 0050.5689.e8b1 DYNAMIC Vx1 90475 0:00:00 ago

B-SW02 Config:

interface Loopback0
ip address 10.101.1.2/32

interface Vxlan1
vxlan source-interface Loopback0
vxlan udp-port 4789
vxlan vlan 300 vni 300300

Router bgp 1234
vlan 300
rd 10.101.1.2:300
route-target both 300:300
redistribute learned

#show mac address-table vlan 300
300 0050.5689.e8b1 DYNAMIC Vx1 90453 0:00:05 ago

Attachments:
0
Answered on March 27, 2019 4:06 pm

Hi Aftab,

The flaps are likely due to mismatch of VxLAN tunnel interface IP address on MLAG’ed switches.

With VxLAN + MLAG, both the switches in MLAG are treated as one logical VTEP from a layer 2 perspective in data plane. So, you’d need to match the VxLAN tunnel interface loopback IP address on the MLAG pair.

For control plane / EVPN peering, you’d use a separate unique loopback per device and typically this loopback IP is also used as the BGP router ID.

In the example below: Lo1 is the VTI, Lo0 is the router ID.

1. Both SW01 and SW02 (VxLAN config)

interface Loopback1
ip address 10.101.1.1/32

interface Vxlan1
vxlan source-interface Loopback1

2. SW01 (EVPN config)

interface Loopback0
ip address 10.201.1.1/32

router bgp 65002
router-id 10.201.1.1
neighbor SPINE_EVPN peer-group
neighbor SPINE_EVPN update-source Loopback0

3. SW02 (EVPN config)

interface Loopback0
ip address 10.201.1.2/32

router bgp 65002
router-id 10.201.1.2
neighbor SPINE_EVPN peer-group
neighbor SPINE_EVPN update-source Loopback0

Hope this helps!

Cheers
Naveen

Post your Answer

You must be logged in to post an answer.