This section focuses on Layer 2 switches. Although traditionally most LAN switches have operated at Layer 2 of the OSI model, an increasing number of Layer 3 switches are now being implemented. A VTEP also needs to know about all 元VNI’s in use across the network.Compared to legacy Ethernet hubs, Ethernet switches improve efficiency and overall network performance. It does not need to know about any L2VNI’s that it doesn’t need to support. Not a lot of vendors support asymmetric IRB.Ī VTEP needs to know about all locally used L2VNI’s. Another form of routing called Asymmetric IRB, uses the ingress VTEP for routing and bridging, while the egress VTEP can only do bridging. The ingress or egress VTEP can perform routing. Essentially, it is the VxLAN equivalent of a VLAN.Īn 元VNI can be used to route between L2VNI’s. This is for bridging hosts on the same layer-2 segment. BGP distributes both of these to all peers. VNI’s can now be considered layer-2 VNI’s (L2VNI) or layer-3 VNI’s (元VNI). Not all platforms support IRB, so choose wisely. There is no need to hairpin traffic through an external router. This means that each switch with a VTEP can also be a router. Good news! Integrated Routing and Bridging (IRB) is supported when using BGP. If the cache expires, the flooding process begins again. The host then begins normal unicast communication with the destination host. The original VTEP receives the response and passes it on to the host. It has already cached its address from before. The local VTEP encapsulates the response and sends it to the original VTEP. This is unicast traffic, as it has a single destination. One of the hosts will respond to the ARP, while the rest will discard the request. The VTEPs forward the ARP to all ports that belong to the VNI. When the VTEPs receive the ARP, they cache the IP to MAC information for possible use later. To do this, it sends the ARP to the appropriate multicast group. The switch needs to send it to all VTEPs with this VNI, as well as to all local ports with this VNI. It will send an ARP request (BUM traffic) to discover this information. The host knows the IP address of the destination, but not its MAC. Imagine a host needs to send traffic to a remote host in the same VNI. Let’s take a moment to think about how this process works.

How mac address learning