Spine Hardware
Cisco ACI spine hardware options includes Nexus 9300 Series fixed form factor switches as well as Nexus 9500 modular switches. Not all switches in the noted switch families can be deployed in ACI mode.
The primary factors that guide spine purchasing decisions are desired port bandwidths, feature requirements, hardware generation, and the required number of target state ports.
Whereas a fixed spine switch has a limited number of ports, a port in a modular platform can scale with the addition of more line cards to a chassis. For this reason, modular chassis are more suitable for fabrics that require massive scale.
Fixed spine platforms satisfy the scalability requirements of small to medium fabrics without problem.
First-Generation Spine Switches
As noted earlier in this chapter, first-generation spine switches are not supported as spines interconnecting ACI fabrics in ACI Multi-Site deployments. Other new solutions, such as Remote Leaf and ACI Multi-Tier also require second-generation spine switches. Understanding first-generation spine platforms is, however, beneficial for historical purposes because a large number of ACI deployments still contain first-generation hardware.
First-generation ACI spine switch models on the market at the time of this writing have model numbers that end in PQ. Table 2-5 lists first-generation Nexus spine switches.
Table 2-5 First-Generation Spine Switches
Characteristic |
Nexus 9336PQ |
Nexus 9736PQ |
|---|---|---|
Form factor |
2 RU fixed switch |
Line card for modular chassis |
Supported modular platforms |
N/A |
Nexus 9504 Nexus 9508 Nexus 9516 |
40 Gigabit Ethernet ports |
36 ports |
36 ports |
100 Gigabit Ethernet ports |
N/A |
N/A |
ACI Multi-Pod support |
Yes |
Yes |
CloudSec support |
No |
No |
Remote Leaf support |
No |
No |
ACI Multi-Tier support |
No |
No |
ACI Multi-Site support |
No |
No |
Even though first-generation spine switches do not support namespace normalization or ingress replication of BUM traffic, they can coexist with second-generation spine switches within a fabric. This coexistence enables companies to integrate fabrics into ACI Multi-Site without having to decommission older spines before the regular hardware refresh cycle.
Second-Generation Spine Switches
In addition to providing support for ACI Multi-Site, Remote Leaf, and ACI Multi-Tier, second-generation spine switch ports operate at both 40 Gigabit Ethernet and 100 Gigabit Ethernet speeds and therefore enable dramatic fabric bandwidth upgrades.
Second-generation spine switches also support MACsec and CloudSec. MACsec enables port-to-port encryption of traffic in transit at line rate. CloudSec enables cross-site encryption at line rate, eliminating the need for intermediary devices to support or perform encryption. Cross-site encryption is also referred to as VTEP-to-VTEP encryption.
Second-generation ACI spine switch models on the market at the time of this writing have model numbers that end in C, EX, and FX. Table 2-6 provides additional details about second-generation spine platforms.
Table 2-6 Second-Generation Spine Switches
Characteristic |
Nexus 9364C |
Nexus 9332C |
Nexus 9732C-EX |
Nexus 9736C-FX |
|---|---|---|---|---|
Form factor |
2 RU fixed |
1 RU fixed |
Line card for modular chassis |
Line card for modular chassis |
Supported modular platforms |
N/A |
N/A |
Nexus 9504 Nexus 9508 Nexus 9516 |
Nexus 9504 Nexus 9508 Nexus 9516 |
40/100 Gigabit Ethernet ports |
64 |
32 |
32 |
36 |
ACI Multi-Pod support |
Yes |
Yes |
Yes |
Yes |
CloudSec support |
Last 16 ports |
Last 8 ports |
N/A |
All ports |
Remote Leaf support |
Yes |
Yes |
Yes |
Yes |
ACI Multi-Tier support |
Yes |
Yes |
Yes |
Yes |
ACI Multi-Site support |
Yes |
Yes |
Yes |
Yes |
In addition to the hardware listed in Table 2-6, Nexus 9732C-FX line cards will be supported as ACI spine line cards in the near future.
New spine switches with 100/400 Gigabit Ethernet ports are also on the horizon. The Nexus 9316D-GX is already available and is supported as an ACI spine. This platform is also in the roadmap for support as a leaf switch. The 100/400 Gigabit Ethernet Nexus 93600CD-GX switch, which is supported as an ACI leaf, is also in the roadmap for use as a spine.
Cisco uses the term cloud scale to refer to the newer Nexus switch models that contain the specialized ASICs needed for larger buffer sizes, larger endpoint tables, and visibility into packets and flows traversing the switch without impacting CPU utilization. Second-generation ACI spine switches fall into the category of cloud-scale switches.