Network Virtualization using Extreme Fabric Connect

Network Virtualization Using Extreme Fabric Connect
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The VXLAN Gateway BEB thus also becomes a VXLAN termination point (VTEP) where a Circuitless IP
address is assigned to be the VTEP source IP and a number of static VXLAN tunnels can be provisioned
towards remote VTEPs across the VXLAN cloud. The VXLAN virtual segments (VXLAN Network Identifiers
- VNI) are then simply mapped to a list of remote VTEP tunnels on one side and to a Fabric L2 I-SID on the
other.
In the Extreme implementation, the VXLAN Gateway functionality is able to operate on SMLT clustered
BEBs (which share a vIST) and is essential in order to provide redundant active-active and Spanning Tree
free gateway functionality for interconnecting what are in effect virtualized L2 broadcast segments.
In an SMLT cluster configuration, both VXLAN Gateways sharing the vIST will need to be configured with
the same Circuitless IP address as VTEP source IP. Both Gateways will announce the same VTEP IP into the
VXLAN IP underlay thus ensuring that both Gateways are used to load balance traffic arriving from the
VXLAN cloud and entering the Extreme Fabric. In the reverse direction load balancing is ensured via the
usual SMLT clustering mechanism which presents a Virtual-BMAC for the SMLT cluster.
A typical deployment scenario is depicted in Figure 61, which uses redundant VXLAN Gateways with a vIST
in between them and maps a VXLAN VNI on one side with a Fabric L2 I-SID on the other. The VXLAN
Gateway will also work with third party VXLAN VTEPs but currently requires all remote VTEPs to be
statically provisioned.
Note
VMware NSX uses a VXLAN overlay but requires OVSDB to discover remote VTEPs and
automate the creation of the VXLAN tunnels. Extreme Networks VSP platforms do support
OVSDB but this is not yet covered in this document.
Figure 61 VXLAN Gateway Capabilities
It should be noted that in the Extreme Networks implementation of VXLAN Gateway the VXLAN VNIs by
virtue of being interconnected with Fabric L2 I-SID can thus be fully integrated into the Fabric L2 & L3
VSNs. Much like an L2 VSN, the VXLAN VNI can be assigned to an IP address, which in turn can belong to a
VRF, which in turn can belong to an L3 VSN.
Like with most other vendors offering VXLAN overlay capabilities, the Extreme VXLAN Gateway will handle
broadcast, unknown, and multicast (BUM) packets using ingress replication, which has the advantage of not
requiring the IP underlay transport network to be IP Multicast capable, but results in a less efficient way of
dealing with BUM traffic. Every BUM packet received from the Fabric side L2 I-SID will thus need to be
ingress replicated by the VXLAN Gateway VTEP as many times as that VTEP has remote VTEPs defined for
the given VNI.