aTCA-3710 User's Guide
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7.2 ADLINK Switch Software Overview
The aTCA-3710 switch ports support Layer 2 forwarding of frames according to IEEE 802.1D and 802.1
Q specifications. Layer 2 forwarding uses the media access control address (MAC address) from the
host's network interface cards (NICs) to decide where to forward frames. Layer 2 switching is hardware
based, which means the Broadcom switches use application-specific integrated circuits (ASICs) to build
and maintain filter tables (also known as MAC address tables or CAM tables).
The aTCA-3710 also supports Layer 3 forwarding of packets. Traditional routers use microprocessors to
make L3 forwarding decisions. The Broadcom switches used by the aTCA-3710 support hardware-based
Layer 3 packet forwarding, and most packet forwarding is handled by the Broadcom hardware ASICs.
Both the MAC and L3 forwarding tables support static configuration of the table entries. Alternatively, the
switch ASICs can also update the MAC tables automatically, while the L3 forwarding tables need be
updated by an external helper. We use the ADLINK updater to update the L3 forwarding table.
Figure 13. Switch Software Blocks
The main user-space switch software components are shown in Figure 13. They are generally grouped
into three layers.
(1) The development SDK includes the Broadcom SDK, GNU Zebra and Net-SNMP. The Broadcom
SDK is used to provide all necessary interfaces (both API and CLI) to configure the switch, or
retrieve configurations and status from the switch. GNU Zebra is used to provide L3 routing protocols
such as RIP, OSPF and BGP. Net-SNMP is used to provide the SNMP protocol development
framework.
(2) The switch functions are mainly implemented in various software stacks as described in the middle
layer of Figure 13. Based on their functions, the software stacks can be further divided into three
groups. The first group is Layer 2 switching stacks, including Port configuration, VLAN, LAG, and
STP. The second group is Layer 3 switching stacks, including basic route configuration, RIP, OSPF
and BGP. The third group includes the other stacks to support SNMP and ACL.
