This section discusses QPPB as it applies to VPRN, IES, and router interfaces. See the IES section and the ‟IP Router Configuration” section in the 7450 ESS, 7750 SR, 7950 XRS, and VSR Router Configuration Guide.
QoS policy propagation using BGP (QPPB) is a feature that allows a route to be installed in the routing table with a forwarding-class and priority so that packets matching the route can receive the associated QoS. The forwarding-class and priority associated with a BGP route are set using BGP import route policies. In the industry, this feature is called QPPB, and even though the feature name refers to BGP specifically. On SR OS, QPPB is supported for BGP (IPv4, IPv6, VPN-IPv4, VPN-IPv6), RIP and static routes.
While SAP ingress and network QoS policies can achieve the same end result as QPPB, the effort involved in creating the QoS policies, keeping them up-to-date, and applying them across many nodes is much greater than with QPPB. This is because of assigning a packet, arriving on a particular IP interface, to a specific forwarding-class and priority/profile, based on the source IP address or destination IP address of the packet. In a typical application of QPPB, a BGP route is advertised with a BGP community attribute that conveys a particular QoS. Routers that receive the advertisement accept the route into their routing table and set the forwarding-class and priority of the route from the community attribute.