Network Virtualization using Extreme Fabric Connect

Network Virtualization Using Extreme Fabric Connect
© 2019 Extreme Networks, Inc. All rights reserved. 47
Figure 16 SPB Fabric Inter-VSN Routing
Conceptually this is no different from a switch that IP routes between VLANs where an IP address was
configured on each VLAN (in the same VRF). However, with L2 VSN this implies that the SPB node must be
capable to handle (de-capsulate and then re-encapsulate) the Mac-in-Mac encapsulation before and after
performing the IP routing function.
Tip
The Extreme Networks VSP series of SPB platforms, which support L3 VSNs and IP-
Shortcuts, can do Inter-VSN routing for both IPv4 and IPv6.
Tip
Performing IP routing between different VPLS VSI segments is not common, within the
MPLS backbone; however, EVPN VXLAN implementations can perform IP routing between
different VXLAN VNIs on the VTEP.
Note
Note that just because it is possible to IP route L2 VSN segments just about anywhere in
the SPB fabric, this should not lead to the temptation of IP routing all user L2 segments
onto the same centrally located SPB node(s). A good design will distribute most IP routing
across the network and locate the routing instances where it makes most sense, for
example, where those user IP subnets are located. This will ensure a more robust
architecture and where the host routes / ARP tables are distributed across all the IP
routing instances for the L3 IP routing domain (L3 VSN or IP Shortcuts).
Fabric Area Network
The Fabric Area Network (FAN) is a reserved L2 domain I-SID used by SPB nodes for enhanced fabric
discovery and auto-configuration functionality, such as the Dynamic Nick-name (DNN).
Tip
Reserved I-SID 16777001 is used and membership of the Fabric Area Network is
announced in TLV 147.