Vlt Bandwidth Monitoring; Rstp And Vlt - Dell Force10 S4810P Configuration Manual

the network. In either case, upon recovery of the peer link or reestablishment of message
forwarding across the interconnect trunk, the two VLT peers resynchronize any MAC addresses
learned while communication was interrupted, and the VLT system continues normal data
forwarding.
• If the primary chassis is rebooted, the secondary chassis takes on the operational role of the
primary. When operation of the original, primary chassis is restored, it takes on the operational
role of the secondary chassis.
• The SNMP MIB reports VLT statistics.

RSTP and VLT

VLT provides loop-free redundant topologies and does not require rapid spanning tree protocol (RSTP).
RSTP can cause temporary port state blocking and may cause topology changes after link or node failures.
Spanning tree topology changes are distributed to the entire layer 2 network, which can cause a
network-wide flush of learned MAC and ARP addresses, requiring these addresses to be re-learned.
However, enabling RSTP can detect potential loops caused by non-system issues such as cabling errors or
incorrect configurations. RSTP is useful for potential loop detection but should be configured using the
specifications below to minimize possible topology changes after link or node failure.
The following recommendations will help you avoid these issues and the associated traffic loss caused by
using rapid spanning trees when VLT is enabled on both VLT peers:
• Any ports at the edge of the spanning tree's operating domain should be configured as edge ports,
which are directly connected to end stations or server racks. Ports connected directly to layer 3-only
routers not running STP should have RSTP disabled or be configured as edge ports.
• Ensure the primary VLT node is the root bridge and the secondary VLT peer node has the second-best
bridge ID in the network. If the primary VLT peer node fails, the secondary VLT peer node becomes
the root bridge, avoiding problems with spanning tree port state changes that occur when a VLT node
fails or recovers.
• Even with this configuration, if the node has non-VLT ports using RSTP that are not configured as
edge ports and are connected to other layer 2 switches, spanning tree topology changes can still be
detected after VLT node recovery. To avoid this scenario, ensure that any non-VLT ports are
configured as edge ports or have RSTP disabled.

VLT Bandwidth Monitoring

When bandwidth usage of the VLTi (ICL) exceeds 80%, a syslog error message
SNMP trap are generated.
Message 1 VLTi Bandwidth Usage Exceeding Threshold Value Error
%STKUNIT0-M:CP %VLTMGR-6-VLT-LAG-ICL: Overall Bandwidth utilization of VLT-ICL-LAG (port-channel 25)
crosses threshold. Bandwidth usage (80% )
(Message 1) and an
Virtual Link Trunking (VLT) | 1071