Users Guide

Topology options
12 Dell EMC Networking OS9 Switch Configuration Guide for VxRail 4.5
• Provides link-level resiliency
• Assures high availability
• Allows a single device to use a LAG across two upstream switches
• Provides Layer 2 multipathing
When combined with Virtual Router Redundancy Protocol (VRRP), a dual switch topology with VLT provides
more efficient Layer 3 forwarding than if VLT is not used. Packets coming from vmnics that are connected to
the backup VRRP router are forwarded by the backup VRRP router, instead of crossing the VLTi to get to the
VRRP master router. In a dual switch topology without VLT, packets coming from vmnics that are connected
to the backup VRRP router must be sent over the inter-switch port channel to be forwarded by the master
VRRP router.
Note: While VxRail nodes use active and standby network adapters instead of LAGs, other servers in the
rack can connect to the VLT switch pair with an LACP LAG for active/active Layer 2 multipathing. For more
information on VLT, see the
Dell Networking OS Configuration Guide for the S5048F-ON System. Guides for
other switch models are available at http://www.dell.com/support.
3.1.2 Dual switch without VLT
The configuration of a switch pair without VLT is supported, but it does not provide the advantages of VLT
covered in the previous section.
The switch pair is cabled as shown in Figure 8. The links connecting the two switches are configured in an
LACP port channel.
Rack 1
S5048F
-Leaf1A S5048F-Leaf1B
LACP
1
VxRail node n
2
1
2
VxRail node 1
1
VxRail node 2
2
25GbE connections
100GbE LACP connections
Dual switch topology without VLT