How Class of Service Works | Juniper Juniper uses the term Class of Service (CoS) to mean Quality of Service (QoS). In this video we’ll see how CoS works on a Junos device. Each router or switch has a buffer (area of memory) where packets go until they can be processed. This can be divided into queues. These are configured as forwarding classes in Junos. Juniper devices usually have 8 or 12 classes, depending on the platform. Before sending packets out, they are placed in one of these queues. We can treat each queue differently, which is how we give some traffic a higher priority than others. When a packet arrives it needs to be classified. This is how the router decides which forwarding class (queue) the packet belongs to. There are three classifiers in Junos; Fixed, Behaviour Aggregate (BA), and Multi field (MF). Fixed puts all packets received on an interface into a particular forwarding class. BA classifies packets based on marking (eg, DSCP marking). An MF classifier uses a firewall filter to find packets matching other conditions (such as IP address and port number). The scheduler is the component that decides which queue is serviced next. This is how we allocate bandwidth to queues. In the next videos, we’ll look at configuration, as well as RED/WRED (drop profiles), per unit schedulers, virtual channels, and packet marking (rewrite). Twitter: https://twitter.com/NetwrkDirection Patreon: https://networkdirection.net/patreon/ LET'S CONNECT 🌏 null 🌏 https://twitter.com/NetwrkDirection 🌏 https://www.patreon.com/NetworkDirection 🌏 https://www.networkdirection.net/ #NetworkDirection #networking