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Packet Processing in the IP Context 37
CopperLink CL2300 User Manual 5 • IP Context Overview
Since the IP context represents a virtual IP4 and IPv6 dual-stack router, it contains up to 251 routing tables for
static routes (not depicted in
figure 13 on page 36). The routing tables decide whether received packets are
delivered to a local application (example, CLI, web server, SIP gateway) or routed via another IP interface to a
remote network host.
The IP context may contain an arbitrary number of logical interfaces. Unlike other operating systems where a net-
work interface is identical to a physical port, we distinguish physical ports from logical interfaces. A logical inter-
face contains all IP-related configuration parameters that are common to all ports, such as the IP address, for
example. As depicted in
figure 13 on page 36, a physical port or circuit is bound bottom-up to one logical IP
interface. Hence, each IP interface reflects the IP-protocol of a physical port or circuit.
Applications such as SIP gateways may also be bound to an IP interface. A top-down binding defines over
which IP interface (and hence over which physical port or circuit) an application communicates.
Packet Processing in the IP Context
Several IP service profiles can be assigned to the individual logical interfaces in the context (see figure 13 ).
These profiles control the flow of packets through the router. They classify packet streams, control which pack-
ets may enter/leave the device via Access Control Lists (ACL), perform Network and Port Address Translation
(NAPT) and deal with Quality-of-Service (QoS) information in packet headers.
Note that there is a different packet-processing chain for each interface depending on its configuration, i.e.,
each interface maintains its own configuration of how the packets are classified, a different ACL, etc. However,
to make having the same configuration on multiple interfaces easier, we moved the configuration parameters to
profiles. The
use command attaches a profile to an interface, such that the same profile can be used by different
interfaces.