The adjacency SID in segment routing is advertised by one router to inform another about the label that should be used to forward traffic to it over a particular link. In this scenario, Router B would advertise an adjacency SID to Router A, which would be usedby Router A to forward traffic to Router B. Based on the exhibit, the adjacency SID that Router B advertises to Router A would be 12.

References:

• Juniper Networks documentation on Segment Routing: Segment Routing Overview

To create connections between routing instances on the same Junos device and route between them, you can use logical tunnel interfaces, which are virtual interfaces that can be used to route traffic between instances without the need for physical connectivity. Additionally, loopback interfaces, which represent the device itself, can be used to route traffic between routing instances as they are always up and can be reached within the device.

References

• Juniper Networks Technical Documentation on Routing Instances
• Juniper Networks Technical Documentation on Logical Tunnel Interfaces

The root bridge in a spanning-tree network is the bridge with the smallest or the lowest bridge ID.

In the absence of a manually configured priority, the Spanning Tree Protocol (STP) elects the root bridge based on the lowest bridge ID, which is a combination of the priority and the MAC address. The device with the lowest MAC address will have the lowest bridge ID and thus be elected as the root bridge.

References

• Juniper Networks Technical Documentation on STP