Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 432)

Inner frame VLAN tagging
In the VXLAN gateway, by default, the encapsulating VTEP strips the inner VLAN tag of the packet
before forwarding it to the remote VTEP. Upon reception, the remote VTEP decapsulates the packets
and a VLAN tag is assigned to the packet based on the one-to-one mapping between the {Port, VLAN}
pair and VNI. The assignment of VLAN tag also depends on whether the access port at the destination
is tagged or untagged. If the access port is tagged, the VLAN tag is added before sending the frame
out after decapsulation. If the access port is untagged, an untagged frame is sent out to the remote
tenant.
Load balancing entropy
Load balancing cannot be achieved using the passenger frame information, as the core networks may
not be VXLAN-aware. To achieve load balancing of the traffic across the VXLAN overlay, the core
network must be configured to use UDP source port for differentiating various passenger flows and
load balancing. The UDP source port varies based on the Layer 3 fields of the passenger packet flow.
It is recommended to calculate the source port number using a hash of fields from the inner packet.
MAC learning
MAC learning is not performed on the {Port, VLAN} pair on both the access and network sides of the
device, as {DMAC, VLAN}-based bridging is not carried out in the E-Line service.
Quality of Service support
The VXLAN-controlled tenant traffic has to compete with the tunneled data traffic. To ensure priority
forwarding of VXLAN-controlled tenant traffic, Quality of Service (QoS) marking is supported. The
Layer 2 User Priority and Layer 3 DSCP are copied from inner to outer headers during encapsulation,
so that the transport Layer 2 and Layer 3 headers reflect the passenger Layer 2 and Layer 3 priority.
NOTE
Copying of the Layer 2 User Priority from the encapsulating Layer 2 header into the outgoing Layer 2
header (after decapsulation) is not supported. However, the DSCP carried in the passenger Layer 3
header is maintained across the VXLAN tunnel.
Unsupported features
The following features are not supported in this VXLAN implementation:
• The ELAN flavor of VXLAN
• Auto discovery of VTEPs
Inner frame VLAN tagging
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