The Cisco Nexus 9000 Series switches support a two-tier spine/leaf topology.

Figure 1. Spine/Leaf Topology. This figure shows an example of a spine/leaf topology with four leaf switches (Cisco Nexus 9396 or 93128) connecting into two spine switches (Cisco Nexus 9508) and two 40G Ethernet uplinks from each leaf to each spine.

The Cisco NX-OS software supports distributed multithreaded processing on symmetric multiprocessors (SMPs), multi-core CPUs, and distributed data module processors. The Cisco NX-OS software offloads computationally intensive tasks, such as hardware table programming, to dedicated processors distributed across the data modules. The modular processes are created on demand, each in a separate protected memory space. Processes are started and system resources are allocated only when you enable a feature. A real-time preemptive scheduler helps to ensure the timely processing of critical functions.

Ethanalyzer is a Cisco NX-OS protocol analyzer tool based on the Wireshark (formerly Ethereal) open source code. Ethanalyzer is a command-line version of Wireshark for capturing and decoding packets. You can use Ethanalyzer to troubleshoot your network and analyze the control-plane traffic. For more information about Ethanalyzer, see the Cisco Nexus 9000 Series NX-OS Troubleshooting Guide.

The Call Home feature continuously monitors hardware and software components to provide e-mail-based notification of critical system events. A versatile range of message formats is available for optimal compatibility with pager services, standard e-mail, and XML-based automated parsing applications. It offers alert grouping capabilities and customizable destination profiles. You can use this feature, for example, to directly page a network support engineer, send an e-mail message to a network operations center (NOC), and employ Cisco AutoNotify services to directly generate a case with the Cisco Technical Assistance Center (TAC). For more information about Smart Call Home, see the Cisco Nexus 9000 Series NX-OS System Management Configuration Guide.

Cisco generic online diagnostics (GOLD) verify that hardware and internal data paths are operating as designed. Boot-time diagnostics, continuous monitoring, and on-demand and scheduled tests are part of the Cisco GOLD feature set. GOLD allows rapid fault isolation and continuous system monitoring. For information about configuring GOLD, see the Cisco Nexus 9000 Series NX-OS System Management Configuration Guide.

Cisco Embedded Event Manager (EEM) is a device and system management feature that helps you to customize behavior based on network events as they happen. For information about configuring EEM, see the Cisco Nexus 9000 Series NX-OS System Management Configuration Guide.

The Cisco NX-OS software is compliant with Simple Network Management Protocol (SNMP) version 1, version 2, and version 3. A large number of MIBs is supported. For more information about SNMP, see the Cisco Nexus 9000 Series NX-OS System Management Configuration Guide.

The Cisco NX-OS software allows you to verify the consistency of a configuration and the availability of necessary hardware resources prior to committing the configuration. You can preconfigure a device and apply the verified configuration at a later time. Configurations also include checkpoints that allow you to roll back to a known good configuration as needed. For more information about rollbacks, see the Cisco Nexus 9000 Series NX-OS System Management Configuration Guide.

With role-based access control (RBAC), you can limit access to device operations by assigning roles to users. You can customize access and restrict it to the users who require it. For more information about RBAC, see the Cisco Nexus 9000 Series NX-OS Security Configuration Guide.

You can use these methods to configure Cisco NX-OS devices:

• The CLI from a Secure Shell (SSH) session, a Telnet session, or the console port. SSH provides a secure connection to the device. The CLI configuration guides are organized by feature. For more information, see the Cisco NX-OS configuration guides. For more information about SSH and Telnet, see the Cisco Nexus 9000 Series NX-OS Security Configuration Guide.
• The XML management interface, which is a programmatic method based on the NETCONF protocol that complements the CLI. For more information, see the Cisco NX-OS XML Interface User Guide.
• The Cisco Data Center Network Management (DCNM) client, which runs on your local PC and uses web services on the Cisco DCNM server. The Cisco DCNM server configures the device over the XML management interface. For more information about the Cisco DCNM client, see the Cisco DCNM Fundamentals Guide.

The Cisco NX-OS software supports high-density, high-performance Ethernet systems and provides the following Ethernet switching features:

• IEEE 802.1D-2004 Rapid and Multiple Spanning Tree Protocols (802.1w and 802.1s)

• IEEE 802.1Q VLANs and trunks

• IEEE 802.3ad link aggregation

• Unidirectional Link Detection (UDLD) in aggressive and standard modes

For more information, see the Cisco Nexus 9000 Series NX-OS Interfaces Configuration Guide and the Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide.

The Cisco NX-OS software supports IP version 4 (IPv4) and IP version 6 (IPv6) and the following routing protocols:

• Open Shortest Path First (OSPF) Protocol Versions 2 (IPv4) and 3 (IPv6)

• Intermediate System-to-Intermediate System (IS-IS) Protocol (IPv4 and IPv6)

• Border Gateway Protocol (BGP) (IPv4 and IPv6)

• Enhanced Interior Gateway Routing Protocol (EIGRP) (IPv4 only)

• Routing Information Protocol Version 2 (RIPv2) (IPv4 only)

The Cisco NX-OS software implementations of these protocols are fully compliant with the latest standards and include 4-byte autonomous system numbers (ASNs) and incremental shortest path first (SPF). All unicast protocols support Non-Stop Forwarding Graceful Restart (NSF-GR). All protocols support all interface types, including Ethernet interfaces, VLAN interfaces, subinterfaces, port channels, and loopback interfaces.

For more information, see the Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide.

The following IP services are available in the Cisco NX-OS software:

• Virtual routing and forwarding (VRF)

• Dynamic Host Configuration Protocol (DHCP) helper

• Hot Standby Router Protocol (HSRP)

• Enhanced object tracking

• Policy-based routing (PBR)

• Unicast graceful restart for all protocols in IPv4 unicast graceful restart for OPSFv3 in IPv6

For more information, see the Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide.

The Cisco NX-OS software includes the following multicast protocols and functions:

• Protocol Independent Multicast (PIM) Version 2 (PIMv2)

• PIM sparse mode (Any-Source Multicast [ASM] for IPv4)

• Anycast rendezvous point (Anycast-RP)

• Multicast NSF for IPv4

• RP-Discovery using bootstrap router (BSR) (Auto-RP and static)

• Internet Group Management Protocol (IGMP) Versions 1, 2, and 3 router role

• IGMPv2 host mode

• IGMP snooping

• Multicast Source Discovery Protocol (MSDP) (for IPv4)

Note	The Cisco NX-OS software does not support PIM dense mode.

For more information, see the Cisco Nexus 9000 Series NX-OS Multicast Routing Configuration Guide.