5-Stage Clos Architecture
5-Stage Clos Overview
5-stage Clos architecture allows for large-scale topologies. With its additional aggregation layer, you can interconnect multiple pods into a single fabric. Superspines provide the additional layer that interconnects multiple pods. Planes are groups of superspines. Each 5-stage topology consists of one or more planes. Each plane consists of one or more superspines. See below for an example.
Careful planning and consideration are required to build large 5-stage Clos networks. Refer to the limitations below when you're designing and validating your 5-stage topology. For assistance, contact Juniper Support.
5-Stage Clos Limitations
- You cannot change a 3-stage topology to a 5-stage topology.
- You must use the same overlay control protocol (static VXLAN or MP-EBGP-EVPN, specified during template creation) for all rack types in all pods.
- Root Cause Analysis is not supported.
- IPv6 / IPv4 support:
- IPv6 support in the underlay depends on the NOS. See the feature matrix.
- IPv6 for applications is not supported until Apstra 4.1.
- The entire fabric across all pods must be either all IPv4, all IPv6 or all dual-stack
- Unsupported external connectivity implementations:
- One generic system connecting to multiple pods
- EVPN with external generic systems on superspines
- External generic systems on spines and leafs in the same pod
- Unsupported blueprint modifications:
- Add or remove superspine planes
5-Stage Clos and EVPN
EVPN networks can be extended across multiple pods within the same blueprint to provide the following added value:
- Scaling: provide any-to-any connectivity for applications distributed across multiple pods.
- Workloads Redistribution: Load-balance applications by migrating a group of applications from one pod to another pod while preserving application IP and MAC addresses.
- Maintenance: Perform pod maintenance by migrating all applications from one pod to another, while preserving the application IP and MAC addresses.
- Active / Standby applications across sites / pods: Deploy A/S applications across multiple pods to provide high availability at pod level, or as part of application migration tasks.
- Facilitate external connectivity for a virtual network from a remote pod without external connectivity.
5-stage Clos networks support the Junos QFX series of switches. You can use the ESI redundancy protocol, create templates from them, and then use those templates as pods in 5-stage Clos networks. For more information about working with Juniper devices with EVPN, see Juniper EVPN Support.
Just like in other Apstra-managed networks, required configuration is rendered to bring up multi-pod networks, and with proprietary Intent-based Networking technology the networks are validated to ensure they operate as designed.
You can create cross-pod virtual networks in the same manner as for 3-stage networks. See Virtual Networks for a comprehensive guide.