Design Reference

Chapter 11: SPBM design guidelines
Shortest Path Bridging MAC (SPBM) is a next generation virtualization technology that revolutionizes the
design, deployment, and operations of enterprise edge campus core networks and data centers. The
benefits of the technology are clearly evident in its ability to provide massive scalability while at the same
time reducing the complexity of the network. SPBM makes network virtualization a much easier paradigm
to deploy within the enterprise environment than other technologies.
The following sections provide design guidelines that illustrate the operational simplicity of SPBM. It also
lists best practices to configure SPBM in your network. For more information about SPBM fundamental
concepts, command structure and basic configuration, see Configuring Avaya VENA Fabric Connect on
Avaya Virtual Services Platform 4000, NN46251–510.
802.1aq standard
Virtual Services Platform 4000 supports the IEEE 802.1aq standard of SPBM. SPBM makes
network virtualization easy to deploy within the enterprise environment by reducing the
complexity of the network while at the same time providing greater scalability. This technology
provides all the features and benefits required by carrier-grade deployments to the enterprise
market without the complexity of alternative technologies traditionally used in carrier
deployments, for example, Multiprotocol Label Switching (MPLS). SPBM integrates into a
single control plane all the functions that MPLS requires multiple layers and protocols to
support.
IS-IS
SPBM eliminates the need for multiple overlay protocols in the core of the network by reducing
the core to a single Ethernet-based, link-state protocol (IS-IS). IS-IS provides virtualization
services, both Layer 2 and Layer 3, using a pure Ethernet technology base. SPBM also uses
IS-IS to discover and advertise the network topology, which enables it to compute the shortest
path to all nodes in the SPBM network.
Spanning Tree is a topology protocol that prevents loops but does not scale very well. Because
SPBM uses IS-IS, which has its own mechanisms to prevent loops, SPBM does not have to
use Spanning Tree to provide a loop free Layer 2 domain.
SPBM uses the IS-IS shortest path trees to populate forwarding tables for the individual
backbone MAC (B-MAC) addresses of each participating node. Depending on the topology,
SPBM supports as many Equal Cost Multipath trees as there are backbone VLAN IDs (B-VIDs)
provisioned (with a maximum of 16 B-VIDs allowed by the standard and 2 allowed in this in
release) per IS-IS instance. IS-IS interfaces operate in point-to-point mode only, which means
that for any given port or MLT interface where IS-IS has been enabled, there can be only one
IS-IS adjacency across that interface.
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