Understanding ACI Hardware and Topologies

Leaf Hardware

Cisco ACI leaf hardware options include Nexus 9300 Series fixed form factor switches. Not all switches in the noted switch families can be deployed in ACI mode.

The primary factors that guide leaf purchasing decisions are the desired port bandwidths, feature requirements, hardware generation, and the required number of target state ports.

First-Generation Leaf Switches

First-generation ACI leaf switches are Nexus 9300 Series platforms that are based on the Application Leaf Engine (ALE) ASICs.

The hardware resources that enable whitelisting of traffic are ternary content-addressable memory (TCAM) resources, referred to as the policy CAM.

Policy CAM sizes vary depending on the hardware. The policy CAM size and behavior limitations in first-generation switches tended to sometimes limit whitelisting projects.

There are also a number of other capability differences between first- and second-generation leaf hardware, such as handling of Layer 4 operations and multicast routing.

Second-Generation Leaf Switches

Second-generation ACI leaf switches are Nexus 9300 Series platforms that are based on cloud-scale ASICs. Second-generation leaf switches support Remote Leaf and ACI Multi-Tier, have significantly larger policy CAM sizes, and offer enhanced hardware capabilities and port speeds.

ACI leaf switches whose model numbers end in EX, FX, FX2, and FXP are considered second-generation leaf switches. Table 2-7 provides details about second-generation switches that have 1/10 Gigabit Ethernet copper port connectivity for servers.

Table 2-7 Second-Generation 1/10 Gigabit Ethernet Copper Leaf Switches

The Nexus 9348GC-FXP switch has 48 ports, offering 100 Mbps or 1 Gigabit Ethernet connectivity. These ports have RJ-45 connections, eliminating the need for transceivers. Due to its low cost and support for cloud-scale features, the Nexus 9348GC-FXP is an ideal replacement for Fabric Extenders.

Table 2-8 details second-generation switches that provide 1/10/25 Gigabit Ethernet fiber port connectivity for servers.

Table 2-8 Second-Generation 1/10/25 Gigabit Ethernet Fiber Leaf Switches

Table 2-9 lists details on the only second-generation switch available at the time of writing that provides 40/100 Gigabit Ethernet connectivity for servers.

Table 2-9 Second-Generation 40/100 Gigabit Ethernet Leaf Switches