Packet Flow Through the Adaptive Services or MultiServices
PIC
You can optionally configure service sets to be applied at one
of three points while the packets transit the router:
An interface service set applied at the inbound interface.
A next-hop service set applied at the forwarding table.
An interface service set applied at the outbound interface.
The packet flow is as follows, graphically displayed in Figure 1. (You can configure a service set as either
an interface service set or a next-hop service set.)
Packets enter the router on the inbound interface.
A policer, filter, service filter, service set, postservice
filter, and input forwarding-table filter are applied sequentially
to the traffic; these are all optional items in the configuration.
If an interface service set is applied, the packets are forwarded
to the AS or MultiServices PIC for services processing and then sent
back to the Packet Forwarding Engine; if a service filter is also
applied, only packets matching the service filter are sent to the
PIC. The optional postservice filter is applied and postprocessing
takes place.
A next-hop service set can be applied to the VPN routing
and forwarding (VRF) table or to inet.0. If it is applied,
packets are sent to the PIC for services processing and sent back
to the Packet Forwarding Engine.
Note:
For NAT, the next-hop service set can only be applied to the
VRF table. For all other services, the next-hop service set can be
applied to either the VRF table or to inet.0.
On the output interface, an output filter, output policer,
and interface service set can be applied sequentially to the traffic
if you have configured any of these items. If an interface service
set is applied, the traffic is forwarded to the PIC for processing
and sent back to the Packet Forwarding Engine, which then forwards
the traffic.
Packets exit the router.
Figure 1: Packet Flow Through the Adaptive
Services or MultiServices PIC
Note:
When an AS PIC experiences persistent back pressure as a result
of high traffic volume for 3 seconds, the condition triggers
an automatic core dump and reboot of the PIC to help clear the blockage.
A system log message at level LOG_ERR is generated. This mechanism
applies to both Layer 2 and Layer 3 service packages.
