Network Virtualization using Extreme Fabric Connect

Network Virtualization Using Extreme Fabric Connect
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data center(s). So only a small proportion of data center host IPs will need to be optimized
against north-south traffic tromboning.
There are two possible approaches with DVR. In the first case, the Extreme’s Fabric Connect is end-to-end
extended from the data centers all the way to the wider campus, as depicted in Figure 73.
Figure 73 Eliminating North-South Tromboning with DVR, Over Campus Fabric
The users will be located in client IP subnets where a campus BEB will be acting as default gateway for
those users. On these campus IP Routers, Extreme offers the ability to let these BEBs join the DVR
Backbone I-SID tree in a listening only role. This is achieved by activating the IS-IS Backbone global switch,
which does not enable DVR on the node, but simply allows that BEB to obtain and maintain a software only
table of all data center hosts, across all DVR domains.
Tip
The ability to let an L3 BEB join the DVR Backbone is possible on all of the Extreme
Networks VSP platforms running VOSS software.
The obtained software table of data center hosts is not programmed in hardware and is not inserted in the
IP routing table and will not have any effect in altering traffic forwarding paths at first. For that to happen
the network administrator will need to take an additional step by defining an accept policy to inject a
selection of those hosts into the corresponding VRF IP routing table. Once the backbone accept policy is
applied, the BEB’s VRF IP routing table will be augmented to include host routes for the injected data
center hosts.
Caution
The backbone accept policy should be defined in such a way that only a selection of
relevant hosts is injected for which traffic tromboning effect needs to be optimized. Do
not inject all data center hosts as there could be thousands of hosts and this could exhaust
the BEB’s IP routing table scaling resources.
The resulting host routes on the campus BEBs will thus always point to the DVR controllers of the DVR
domain where the host is located. These routes will also automatically update themselves should the host
VM be migrated to a different DVR domain.