L3 Subsystem; Figure 4-11 Functional Block Diagram Of The L3 Subsystem - Zte ZXR10 5900E Product Description

4.3.4

L3 Subsystem

By software layer, the L3 subsystem consists of the service control layer and
data-forwarding layer. Where, the service control layer is composed of the TCP/IP and IP
forwarding support subsystem. The TCP/IP consists of the support protocols and routing
protocols. The support protocols are the basic protocols in the Ipv4 protocol suite,
providing services to the dynamic routing protocols, while acting as the entities of
network management and system monitoring. As the service provider for the upper-layer
application entities on the whole router system, support protocols consist of IP, ARP,
ICMP, IGMP, TCP, UDP and Telnet protocol entities. Routing protocols are used to
generate dynamic routes, and they consist of unicast routing protocols such as RIP,
OSPF, and BGP, and multicast routing protocols such as IGMP, PIM-SM, MSDP and
MBGP, and they provide related upper-layer protocols such as LDP, VRRP, and RSVP.
The IP forwarding and support subsystem is responsible for deletion and modification of
the forwarding table and the related strategies, and establishment and maintenance of
indexes, and data interaction between the CPU and switch chip. The IP data forwarding
layer inputs, forwards and outputs the data of the strategies, rules and routing tables
created by the switch chip according to the IP service control layer.

Figure 4-11 Functional Block Diagram of the L3 Subsystem

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