Lesson plan
Flex links
Flex links is a network switch feature in Cisco equipment which enables redundancy and load balancing at the layer 2 level. The feature serves as an alternative to Spanning Tree Protocol or link aggregation. A pair of layer 2 interfaces, such as switch ports or port channels, has one interface configured as a backup to the other. If the primary link fails, the backup link takes over traffic forwarding. At any point of time, only one interface will be in linkup state and actively forwarding traffic. If the primary link shuts down, the standby link takes up the duty and starts forwarding traffic and becomes the primary link. When the failing link comes back up active, it goes into standby mode and does not participate in traffic forwarding and becomes the backup link. This behaviour can be changed with pre-emption mode which makes the failed link the primary link when it becomes available again. Load balancing in Flex links work at VLAN level. Both the ports in the Flex link pair can be made to forward traffic simultaneously. One port in the flex links pair can be configured to forward traffic belonging to VLANs 1-50 and the other can forward traffic for VLANs 51-100. Mutually exclusive VLANs are load sharing the traffic between the Flex link pairs. If one of the ports fails, the other active link forwards all the traffic.
Article summary
Flex links is a network switch feature in Cisco equipment which enables redundancy and load balancing at the layer 2 level. The feature serves as an alternative to Spanning Tree Protocol or link aggregation. A pair of layer 2 interfaces, such as switch ports or port channels, has one interface configured as a backup to the other. If the primary link fails, the backup link takes over traffic forwarding. At any point of time, only one interface will be in linkup state and actively forwarding traffic. If the primary link shuts down, the standby link takes up the duty and starts forwarding traffic and becomes the primary link. When the failing link comes back up active, it goes into standby mode and does not participate in traffic forwarding and becomes the backup link. This behaviour can be changed with pre-emption mode which makes the failed link the primary link when it becomes available again. Load balancing in Flex links work at VLAN level. Both the ports in the Flex link pair can be made to forward traffic simultaneously. One port in the flex links pair can be configured to forward traffic belonging to VLANs 1-50 and the other can forward traffic for VLANs 51-100. Mutually exclusive VLANs are load sharing the traffic between the Flex link pairs. If one of the ports fails, the other active link forwards all the traffic.
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.