Vyatta Network OS Documentation

Learn how to install, configure and operate the Vyatta NOS, which helps drive our virtual networking & physical platforms portfolio.

Packet flow through Vyatta NOS

How packets travel through Vyatta NOS and interact with key entities.

Figure 1. Packet flow through Vyatta NOS
Layer 1 3 4 5 7 8 9 10 1 2 6
  1. Ingress interface
    As the packets arrive at the ingress interface the system can separate them into specifically identified vLAN traffic, and all other traffic (non-vLAN).
  2. Forwarding lookup
    The system uses forwarding lookup to identify the appropriate egress interface to use. Then, the system will apply any QoS policy that is attached to the egress interface or virtual interface (VIF) to the packets.
    Note: We use VIFs to identify and configure specific vLAN attributes on an interface.
  3. Virtual interfaces VIFs
  4. Class/profile
    Classification splits the packet stream across 32 profile queues.
  5. 32 profile queues
    The system maps each profile queue to one of four traffic classes.
  6. Four traffic classes, each with eight WRR queues
    The scheduling part of the QoS profile determines the sequence by which the system will pull packets from the profile queues. The system will use the weighted round robin (WRR) scheduling method to pull packets from the eight queues in each traffic class.
  7. Strict priority TC0>TC1>TC2>TC3
    The system will pull packets from the four traffic classes in the profile in strict priority order.
  8. Fair Queuing Interface VIFs
    The system services each profile fairly.
  9. Fair queuing across the vLANs
    The system services each vLAN fairly.
  10. Egress interface
    We can attach a QoS policy to each interface at egress.
    • You do not have to configure each interface to have a QoS policy attached to it.
    • You can attach the same QoS policy to multiple interfaces or VIFs — but each policy instance operates independently.