Network Virtualization using Extreme Fabric Connect

Network Virtualization Using Extreme Fabric Connect
© 2019 Extreme Networks, Inc. All rights reserved. 27
Guiding Principles
The goal of network virtualization is to decouple the network users and their applications from the
underlying infrastructure so that those users and applications can be segmented from other users and
applications while still sharing the same physical network infrastructure resources (bandwidth and
connectivity). One network must therefore support many different virtual networks.
These networks become logical and their addressing (IP routes and user-VLANs where end-station MACs
are learned) is only applicable within the Virtual Services Network (VSN) to which they belong. Leveraging
network virtualization to segregate network users into different domains is always far superior than trying
to achieve and maintain the same goal by leaving all users and services in a single Global Routing Table
(GRT) with a common addressable IP address space, and then attempting to manage connectivity with
extensive use of Access Control Lists (ACLs) or by making all VLANs non-routable within the network and
performing all routing across firewall interfaces.
Figure 7 Virtualization of Logical Networks over SPB
The demarcation of physical and virtual networks has never been as rigorous as it is with SPB where the
Ethernet Fabric deals with SPB Backbone MAC addresses (BMAC) tied to the physical infrastructure and
used by IS-IS to compute the shortest path across the physical topology. End-user MAC addresses are
handled within L2 VSN service types and IP routes (IPv4 or IPv6) are advertised within L3 VSN service
types. In short, with SPB, IP routing is no longer the foundation of the network backbone, but becomes
purely a service above it.
Tip
For the sake of comparison, MPLS needs an underlying IPv4 IGP in order to operate,
which in carrier networks is contained inside the core and used only by MPLS (and LDP
and iBGP). But in Enterprise networks, this is seldom the case. MPLS deployed in an
enterprise environment is thus inconsistent in its use of VRF-0 (Global Router), which
plays a dual role of foundation of the MPLS’s heavy control plane protocol stack as well as
acting as a legitimate L3 domain for some network users and applications.
When virtualization is combined with a simple and consistent end-point provisioning based on a common
Service-ID (I-SID) concept, as is the case with Fabric Connect, we have a powerful solution for creating
virtual networks on demand.
This makes the Extreme Networks Fabric Connect architecture an ideal SDN framework, which is not based
on overlay technologies and is not limited to the data center alone but instead becomes an end-to-end
network foundation and enables a highly automated and programmable SDN edge
2
with IEEE 802.1Qcj
2
See Fabric and VSN Security on page 154.