VSF restrictions
• VSF is mutually exclusive with distributed trunking, mesh, and Q-in-Q.
• VSF port restrictions:
◦ Must be 10Gbps/1Gbps.
◦ A VSF link can only comprise ports with the same speed; either all 10G or all 1G. A VSF port speed which
does not match with the global port speed, will be in a down state. The command
show vsf link
detail
will display an error message.
◦ Maximum eight ports can be configured on one VSF link.
◦ VSF ports must be directly connected and there should be no transit devices between members.
• In a VSF virtual chassis, flow-control is not supported between ports on different chassis across VSF links.
• A VSF stack downgrade is not allowed if we try to downgrade a 2930 VSF stack having a stack size greater
than four members, to an image lesser than 16.06.
• For switches running software versions lesser than 16.06, it is recommended to first upgrade to 16.06 for
supporting a stack having more than four members.
• VSF merge between a fragment running a software version 16.06 and a fragment running an image lesser
than 16.06 is not recommended.
• A power outage or cable connection failures can split a stack with greater than four members, into more than
two fragments (for example, 1-2-3-4, 5-6, and 7-8). To restore the stack to its previous state after addressing
the issues, ensure that not more than two fragments are merged at a time. For example, merge 1-2-3-4 with
5-6, followed by merging 1-2-3-4-5-6 with 7-8.
VSF Use Cases
Use Case 1: Multiple Active Detection
What is MAD?
Multiple Active Detection (MAD) is a protection mechanism against the fallout of a VSF stack split. A stack split
occurs when there is a connectivity failure between the two stack switches. The simplest protection against
connectivity failure is to have multiple redundant ports in the VSF link.
The two switches operate in a “split-brain” scenario. Both split fragments cannot talk to each other and are
forwarding traffic, but:
• they have the same MAC address,
• they have the same IP addresses on all VLANs, and
• depending on the deployment, they are likely to be connected to same uplink/downlink switches though a link-
aggregation.
A MAD protocol must be enabled to prevent network-wide issues that a stack split can cause. MAD protocols
attempt to detect the presence of the other stack fragment. If detected, the goal of MAD is to keep only one stack
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Aruba 2930F / 2930M Management and Configuration Guide
for ArubaOS-Switch 16.08
