Generic Systems vs. External Generic Systems

When to use a generic system and when to use an external generic system:

Generic System

  • For attaching compute/storage
  • Can only be connected to a single rack
  • Appears in the topology as part of a rack

External Generic System

  • For middleware devices, such as firewalls, load balancers, external routers and so on*
  • Can be connected to multiple racks
  • Appears in the topology outside of racks for easier identification

* In many cases, middleware boxes only connect to a single border leaf pair in a rack, but configuring it as an external generic system allows it to be visually separated outside of the rack. However, if there is a requirement such as connecting to an external router (MX) via BGP and you want to provide rack redundancy, then you would use an external generic system to allow this multi-rack connectivity.

Spine-leaf network topology with two spines spine1 and spine2 connected to leaves leaf1 leaf2 and leaf3. External connection rtr_leaf1_leaf2 is linked to leaf1 and leaf2. Systems under leaf1 and leaf2 include rack1-server1 switch1-server1 and switch2-server1. Leaf3 connects to switch3-server1. EVPN segments evpn_esi_001 group leaf1 leaf2 and their systems while evpn_single_001 groups leaf3 and its system.