Network Virtualization using Extreme Fabric Connect

Network Virtualization Using Extreme Fabric Connect
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configuration or identity-based networking authentication. These VLANs are associated with a VRF on the
BEB nodes where a given VLAN can belong to one and only one VRF. Multiple VRFs can be configured,
each belonging to a different Fabric wide service identifier (I-SID), thus providing multi-tenancy in L3 VSN.
Figure 3 Virtualization with SPB L3 VSNs
Tip
Benefits of SPB L3 VSNs over MPLS-VPNs are:
• Simple service definition via Service Identifier (I-SID) configuration on end-point
VRF instead of having to define multiple complex import and export BGP Route
Targets and BGP Route Descriptors.
• The same I-SID is also used in the Mac-in-Mac packet encapsulation, whereas with
MPLS-VPNs, the inner MPLS labels (used as VPN-id) only have an indirect
correlation to BGP Route Target configuration.
• No need for any BGP (and therefore no need for BGP Route Reflectors either).
• No need for MPLS (and therefore no need for an underlying IP IGP or LDP).
• No IP interfaces/subnets inside the Ethernet Fabric. IP interfaces exist only on
VLANs where end-stations connect; that is, IP interfaces only exist as gateways for
the VSN services they terminate.
• L3 VSNs can be IP Multicast enabled with one command per termination node (no
need for complex IETF Draft Rosen or Next-Gen MVPNs support).
• Sub-second convergence because SPB relies on a single link state routing protocol
(IS-IS), whereas MPLS is reliant on a BGP-LDP-OSPF protocol stack, which is
significantly slower to reconverge.
A comparison of the traditional designs used to deliver Layer 3 virtualization with the SPB architecture can
be found in Table 2.
Table 2 – SPB vs Traditional L3 Virtualization Technologies