Hello everyone,
Today, I'm going to share with you the discussion on the uninterrupted service solution in the new HCIE R&S lab.
Topic
The figure shows the backbone network of an enterprise. ISIS is deployed on R1, R2, R3, and R4. According to the routing entries generated by ISIS, the traffic intercommunication between the headquarters and each branch is realized. Now you need to cut over the equipment, replace R3 with low-performance equipment with high-performance equipment. At the same time, you need to ensure that the business is not interrupted as much as possible. Please give three solutions for the uninterrupted business.
Resolution
1. Overload bit. IS-IS Overload uses the IS-IS OL flag to identify the overload status. After the overload flag is set on R3, other devices do not use R3 for SPF calculation and only calculate the direct route on R3. In this case, traffic is preferentially forwarded through a reachable uplink. In this case, R2 forwards all traffic and replaces R3 with a new device. After the configuration is restored, the traffic path recovers to the status before the replacement.
2. Modify the path cost. Adjust the cost of the uplink to be lower than that of the downlink. Direct traffic to the uplink and replace R3. After the replacement, restore the cost to the original value and switch traffic back to the original link.
3. After the configuration is imported to the new device, the device is directly deployed on the live network. Switch the traffic to R2 and the new device so that no service traffic passes through R3 to prevent service packets from being discarded when the device is removed. Remove the cables from R3 and remove the device from the rack to complete the cutover.
4. Change the weight of the next-hop (nexthop xx weight xx). Adjust the weight value of the uplink to be lower than the weight value of the downlink (a smaller weight value indicates a higher priority). In the case of route load balancing, data is preferentially transmitted to the headquarters through the uplink. After all, traffic is diverted to the upstream device, R3 is replaced. After the replacement is complete, the priority weight is restored to the original value, and traffic is switched back to the original link.
That is all I want to share with you!
