Network Virtualization using Extreme Fabric Connect

Network Virtualization Using Extreme Fabric Connect
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reachability of DVR host IP routes across different DVR domains as well as to campus BEBs that may have
been activated to join the same DVR Backbone.
DVR Leaf
The DVR leaf is typically deployed as a data center ToR Fabric Connect switch. It is a switch with a dual
personality. From a provisioning and management perspective, the DVR leaf is an L2 BEB where the only
configuration possible is to associate server access ports to L2 VSN segments. Though even this
configuration can be eliminated via the use of Extreme Management Center ExtremeConnect integration
with VMware and Microsoft HyperV or the use of Fabric Attach where the server hypervisor supports Open
vSwitch (OVS).
Note
A DVR leaf node only supports Switched-UNI on its access ports. Platform VLANs and
hence CVLAN UNI cannot be configured on a DVR leaf.
However, from a data plane perspective, the DVR leaf is a VRF-aware IP router capable of acting as a first-
hop default gateway for any server or station locally attached to it. The DVR leaf has no IP address to do
this, but it does have shared ownership of the DVR Gateway MAC address which was configured on the
DVR controller(s) within the same DVR domain. This is how the DVR anycast gateway is implemented.
Tip
There are only three possible IP addresses that can be configured on a DVR leaf:
• IS-IS management IP: used for in-band management of the node.
• Out-of-band IP: used for out-of-band management of the node.
• vIST IP: used if the node is forming an SMLT cluster with another DVR leaf node.
Whenever a new VRF and DVR IP Gateway are provisioned on the DVR controllers, all the DVR leaf nodes
within the same DVR domain will be instructed to allocate a VRF and MAC routing interface to match. If
SPB Multicast was enabled on the DVR IP Gateway created on the DVR controller, then the DVR leaf will
also automatically enable its interface for SPB Multicast.
From a data plane IP routing perspective, the DVR leaf has IP host routes for every server host IP
connected to the DVR domain, which allows it to perform shortest path host-based IP routing within any of
the L3 SPB service types (IP Shortcuts and L3 VSNs). When servers or VMs ARP for their default gateway
(the DVR Gateway IP) the locally attached DVR leaf will respond by providing the DVR Gateway MAC. The
DVR leaf nodes are thus immediately aware of the host IPs that are locally attached to them and they
advertise these host IP routes to every other DVR node (controller and leaf) within the DVR domain using
the highly efficient point-multipoint IS-IS control plane I-SID based signalling. The DVR leafs are also able to
handle hypervisor GARP and RARP messages to detect when a host VM IP has moved which allows DVR to
constantly keep track of host IPs even when they are mobile.
Note
VMware Vmotion uses RARP packets. Microsoft Hyper-V uses GARP packets. In both
cases, it is the hypervisor, not the VMs involved, that generates those packets in order to
facilitate the VM move.