VXLAN MAC issue

Created: Apr 30, 2019 18:25:12Latest reply: Apr 30, 2019 19:41:27 51 1 0 0
  Rewarded Hi-coins: 0 (problem resolved)

I am using VXLAN to bridge layer 2 between the switches on various different VLANs/bridge domains and I am seeing strange behaviour with the output from the following command

 

display mac-address bridge-domain <xxxx>

 

As an example I have set up a test between two of the switches using bridge domain / vlan 2039, switch 1 has a Vbdif interface with ip address 192.168.250.1 and switch 2 a Vbdif interface with 192.168.250.4.

 

I can ping between the two switches across VXLAN and for around 10 minutes the mac-address of the interface on the distant switch is visible as follows:

 

<ce1 >dis mac-address bridge-domain 2039

-------------------------------------------------------------------------------

MAC Address   VLAN/VSI/BD                      Learned-From        Type     

-------------------------------------------------------------------------------

d0ef-c19f-8c5f-/-/2039                         192.168.35.188      dynamic   

 

However after around 10 minutes this mac-address stops appearing in the output, despite still being visible in the switches arp table (and ping able).

 

If I shut down the Vbdif interface and then reenable it the mac address shows up in the output again, and I also observed that if I wait for the arp timer to expire (default 20 minutes) then the mac-address shows up once again, until a further 10minutes has past at which point it disappears.

 

Is this something you could advise on? Is it possibly a bug or a discrepancy between the timer values or similar?

 

  • x
  • convention:

Featured Answers
Moderator Created Apr 30, 2019 19:41:27 Helpful(0) Helpful(0)

Good day!

Two S5720HI devices establish a VXLAN Layer 2 tunnel and use the VBDIF interface address. When the VBDIF interface is pinged with each other, the VXLAN packet (UDP packet, dport 4789) is encapsulated based on the ARP information.

The information is based on the destination address of the VXLAN tunnel - it is the next hop information and the inner address is the corresponding VBDIF interface address. 

Therefore, in the case of ping OK, you should learn the MAC address of the outer VLAN and you will not learn the corresponding BD. This is normal.
  • x
  • convention:

All Answers
Popeye_Wang Moderator Created Apr 30, 2019 19:41:27 Helpful(0) Helpful(0)

Good day!

Two S5720HI devices establish a VXLAN Layer 2 tunnel and use the VBDIF interface address. When the VBDIF interface is pinged with each other, the VXLAN packet (UDP packet, dport 4789) is encapsulated based on the ARP information.

The information is based on the destination address of the VXLAN tunnel - it is the next hop information and the inner address is the corresponding VBDIF interface address. 

Therefore, in the case of ping OK, you should learn the MAC address of the outer VLAN and you will not learn the corresponding BD. This is normal.
  • x
  • convention:

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