Deployment Guide

Sample RSTP Conguration
The following is a sample of an RSTP conguration.
Using the example shown in the Protocol Overview section as a sample VLT topology, the primary VLT switch sends BPDUs to an access
device (switch or server) with its own RSTP bridge ID. BPDUs generated by an RSTP-enabled access device are only processed by the
primary VLT switch. The secondary VLT switch tunnels the BPDUs that it receives to the primary VLT switch over the VLT interconnect.
Only the primary VLT switch determines the RSTP roles and states on VLT ports and ensures that the VLT interconnect link is never
blocked.
In the case of a primary VLT switch failure, the secondary switch starts sending BPDUs with its own bridge ID and inherits all the port
states from the last synchronization with the primary switch. An access device never detects the change in primary/secondary roles and
does not see it as a topology change.
The following examples show the RSTP conguration that you must perform on each peer switch to prevent forwarding loops.
Congure RSTP on VLT Peers to Prevent Forwarding Loops (VLT Peer 1)
Dell_VLTpeer1(conf)#protocol spanning-tree rstp
Dell_VLTpeer1(conf-rstp)#no disable
Dell_VLTpeer1(conf-rstp)#bridge-priority 4096
Congure RSTP on VLT Peers to Prevent Forwarding Loops (VLT Peer 2)
Dell_VLTpeer2(conf)#protocol spanning-tree rstp
Dell_VLTpeer2(conf-rstp)#no disable
Dell_VLTpeer2(conf-rstp)#bridge-priority 0
Conguring VLT
To congure virtual link trunking and create a VLT domain in which two switches are physically connected and treated as a single port
channel by access devices, you must congure the following settings on each VLT peer device.
Prerequisites: Before you begin, make sure that both VLT peer switches are running the same Dell Networking OS version and are
congured for RSTP as described in RSTP Conguration. For VRRP operation, ensure that you congure VRRP groups and L3 routing on
each VLT peer as described in
VLT and VRRP interoperability in the Conguration Notessection.
1 Congure the VLT interconnect for the VLT domain. The primary and secondary switch roles in the VLT domain are automatically
assigned after you congure both sides of the VLTi.
NOTE
: If you use a third-party ToR unit, to avoid potential problems if you reboot the VLT peers, Dell recommends
using static LAGs on the VLTi between VLT peers.
2 Enable VLT and create a VLT domain ID. VLT automatically selects a system MAC address.
3 Congure a backup link for the VLT domain.
4 (Optional) Manually recongure the default VLT settings, such as the MAC address and VLT primary/ secondary roles.
5 Connect the peer switches in a VLT domain to an attached access device (switch or server).
Conguring a VLT Interconnect
To congure a VLT interconnect, follow these steps.
1 Congure the port channel for the VLT interconnect on a VLT switch and enter interface conguration mode.
Virtual Link Trunking (VLT)
873