Services
7750 SR OS Services Guide Page 47
Operation of Class-Based Forwarding over SDP LSPs
The 7750 SR class-based forwarding feature applies to a set of LSPs that are part of the same SDP.
Each LSP must be configured as part of an SDP specifying the forwarding classes it will support.
A forwarding class can only be assigned to one LSP in a given SDP, meaning that only one LSP
within an SDP will support a given class of service. However, multiple classes of services can be
assigned to an LSP. Both RSVP and static LSPs are allowed. All subclasses will be assigned to the
same LSP as the parent forwarding class.
When a service packet is received at an ingress SAP, it is classified into one of the eight 7750 SR
forwarding classes. If the packet will leave the SR on an SDP that is configured for class-based
forwarding, the outgoing LSP will be selected based on the packet's forwarding class. Each SDP
has a default LSP. The default LSP is used to forward a received packet that was classified at the
ingress SAP into a forwarding class for which the SDP does not have an explicitly-configured LSP
association. It is also used to forward a received packet if the LSP supporting its forwarding class
is down. Note that the SDP goes down if the default LSP is down.
Class-based forwarding can be applied to all services supported by the 7750 SR. For VPLS
services, explicit FC-to-LSP mappings are used for known unicast packets. Multicast and
broadcast packets use the default LSP. There is a per-SDP user configuration that optionally
overrides this behavior to specify an LSP to be used for multicast/broadcast packets.
VLL service packets are forwarded based on their forwarding class only if shared queuing is
enabled on the ingress SAP. Otherwise, the class-forwarding command will have no effect and the
VLL packets will be forwarded by hashing the service ID as per the hash algorithm used for LAG
and ECMP.
To Next Page
Loading...
