Posted on January 30, 2019 8:15 pm
 |  Asked by Alessandro Onesta
 |  123 views
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Hi,

we have a network topology which connencts 3 sites using 3 different P2P link based on VxLAN over IP-OSPF links (see attached file).
My doubt is about loop protection, in all 3 links we allow all the vlan/vni so, potentially, a L2 loop can happens, as I know STP BPDU are filtered over vxlan links, do we need some l2 loop protection? or the VxLAN technology protects about L2 Loops?

Many thanks in advance
Regards

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Posted by Alex
Answered on January 30, 2019 9:38 pm

VXLAN utilises a split-horizon model to avoid a loop in this topology, BUM traffic received over a VXLAN tunnel is only forwarded to the local ports, it’s not forwarded back out a VXLAN tunnel. However this doesn’t prevent the potential for a loop, if the correct protection methods (STP etc) are not put in place in each of the local sites.

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Posted by Yashwanth Veluri
Answered on January 31, 2019 3:47 am

Hey Alessandro,

If the links between the sites are L3 interfaces, there wouldn’t be an L2 loop. But if they are normal L2 links allowing vlans, then both the vxlan frames as well as STP frames would be exchanged between the devices. The STP frames will not be vxlan encapsulated and exchanged between the sites, but they will be sent normally (unencapsulated) over the L2 links. This way, the STP would help in loop prevention.

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Posted by Alessandro Onesta
Answered on January 31, 2019 2:37 pm

Many thanks guys

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