cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Announcements

651
Views
0
Helpful
2
Replies
Network-learner
Beginner

How traffic enters the vxlan tunnel,I mean the NVE interace

Hi All,

 

Please could someone explain me how the traffic enters the vxlan tunnel,I am comparing this with GRE and in GRE the routing process puts the traffic in tunnel interface but how does this happen in NVE.I think I  am missing a basic understanding here.

 

 

 

Thanks

2 REPLIES 2
Network-learner
Beginner

Hi All.

Please could someone respond and help.

Thanks

Hello @Network-learner !

 

I'll try to simplify this a bit from my understanding of how it works .

The "magic" happens when you actually map a VLAN to a L2VNI or a VRF to a L3VNI - depending on your scenario.

 

Let's take VLAN 10 for example - traffic comes into a port and arrives tagged or the switches places the tag of VLAN 10 on that packet . After that the switch strips the VLAN tag (not taking into account Q-in-VNI or other complex scenarios here) and then places the VXLAN header over it . After this the traffic is processed based on the information of "NVE" interface - it searches for all the VTEP peers for which it exchanges information for that specific VNI . After one or more peers are detected - the traffic is encapsulated to these using the source-interface of the NVE interface and sent via multicast or unicast - depending on if the traffic is either BUM traffic or plain unicast traffic. Note that these VTEP adjacencies are usually established beforehand .

 

Comparing this to the GRE tunnel interface might not be the best idea - usually over a GRE interface you do routing - and it makes sens that you see the traffic "outgoing" via the GRE tunnel interface in the routing table . It's not the same for VXLAN - you're talking about Layer 2 and Layer 3 traffic both in that case. Long story short - you map your VLAN to you VXLAN and then send the traffic out using the source IP address of the NVE interface towards the peer switch you have a VTEP adjacency with.

 

Hope that clarifies some things for you.

 

Best regards!


Horia