Zte ZXR10 5900 Product Description page 64

ZXR10 5900 5200 Product Description
In broadband access applications, the software forwarding support subsystem performs
user authentication, detection, management and billing, and at the same time maintains
user access control information of the Ethernet ASIC chip.
4.3.3.4 IP Support Protocol Sub-System
It consists of the following sub-modules.
IP basic protocol module

This module includes IP/ICMP/ARP protocol processing and routing table management.
The IP protocol part transfers IP packets over the network layer, while providing
functions such as error control, IP option, TOS, segment reassembly and security
service etc. The IP module provides local transfer and forwarding of IP packets, for
encapsulation and distribution for upper-layer protocols.
The ARP protocol part provides the mapping between IP addresses to MAC addresses.
ARP packets are directly encapsulated as link-layer frames (Ethernet frames in this
system), but they are closely combined with IP. With ARP mechanism, the MAC address
corresponding to an IP address can be obtained.
The ICMP protocol part provides control and error information transfer function. ICMP
packets are encapsulated as IP packets, which is tightly integrated with the IP layer. This
is a part that IP protocol must implement. It includes receiving ICMP error packets,
sending them to the appropriate network layer for processing, responding to ICMP
request packets, creating and sending ICMP packets under the request of the IP layer or
transmission layer.
The IP routing table management part performs operation and maintenance of the
routing table, providing interfaces to the routing protocol for creating, updating, and
deleting routing tables' entries, and providing related interfaces for route hashing for
route search from the IP layer.
The TCP protocol processing module processes the TCP data from the IP basic

protocol module, sending the packets of the protocols such as TELNET and BGP to
the appropriate processing modules.
 The UDP protocol processing module processes UDP data from IP, and forwards
data from protocols such as FTP, SNMP, and DHCP to appropriate processing
modules.
4.3.3.5 Unicast Routing Sub-System
As the source for the creation of unicast route forwarding table for ZXR10 59/52 series,
unicast routing protocol sub-system collect network topology information by interacting
with other routers in the network to create IP unicast routing table. In addition, it also
transfers routing table information to IP forwarding layer, so that ZXR10 59/52 series
products can provide unicast IP packet forwarding.
As Figure 29 shows, the unicast routing sub-system contains the following modules:
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