Network Virtualization using Extreme Fabric Connect

Network Virtualization Using Extreme Fabric Connect
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Extreme Networks Fabric Connect VPN XA1400 (XA1440 & XA1480) platforms natively
support Fabric Extend in IP VXLAN mode but can also support Fabric Extend with an
IPSec encapsulation; both are implemented with software switching.
Figure 52 Fabric Extend Pairing of ONA with VSP4000
Note
Extreme Networks VSP 4450/4850 platforms do not have VXLAN capable hardware and
must therefore be paired with an Open Network Adapter (ONA) to support Fabric Extend
in IP VXLAN mode. See Figure 52.
Clearly the use of a VXLAN or IPsec encapsulation has implications with regards to the maximum frame
sizes that can be expected to transit over the WAN service. SPB’s Mac-in-Mac encapsulation already adds
22 bytes to a normal Ethernet frame size, and a VXLAN encapsulation will add a further 50 bytes, as can be
seen in Figure 53. Hence the largest possible Ethernet packet with frame size of 1518 (untagged) / 1522
(tagged) bytes (for an IP MTU of 1500 bytes) will reach a maximum size of 1594 bytes. With an IPsec
encapsulation the overhead is even larger, though IPsec will typically be used over the Internet and will thus
require fragmentation and reassembly anyway.
Caution
Fabric Extend in IP (VXLAN) mode requires the WAN to support frame sizes of 1600
bytes.
When planning a Fabric Extend deployment, it is therefore important to verify with the WAN provider that
the WAN service will be able to support such MTU requirements.