What is a Layer 3 Switch?
Moxa's Layer 3 switches can be used to partition a large-scale LAN into multiple subnets for better network performance. The hardware on a Layer 3 switch is optimized to transmit data as fast as Layer 2 switches, but Layer 3 switches use the IP address to make switching decisions (on OSI Layer 3), the same as a router. The 802.1Q VLAN of a Layer 2 switch allows network operators to configure and maintain networks more efficiently, but cross VLAN communication still relies on traditional Layer 3 routers.
Both routers and Layer 3 switches use a routing protocol and routing table to determine the best path. However, compared to routers, which are usually software-based, Layer 3 switches are faster and less expensive due to the built-in switching hardware. Optimized chips and full-wire speed IP frame forwarding ensures performance that is suitable for connections between VLANs.
Instead of using a Layer 2 Ethernet switch MAC table, the PT-7828 has a built-in IP routing table that supports the forwarding of IP frames. Network administrators must configure and maintain this IP routing table manually, and if any changes are made to the network topology, the administrator will need to reconfigure the routing table.
Routing Information Protocol (RIP)
In addition to static routing, the PT-7828 also has a built-in IP routing table that can be set up and updated dynamically by routing protocol. RIP is an often-used routing protocol that uses the Bellman-Ford algorithm and "hop count" measurement to determine how packets should be routed from one network to another.
Open Shortest Path First (OSPF)
The PT-7828 series also supports OSPF, which uses “Link State” instead of “hop count” to determine the network route. OSPF is more complicated than RIP. However, compared to RIP, OSPF has faster network convergence and less network traffic. Both RIP and OSPF are usually referred to as Interior Gateway Protocols (IGP).
Static versus Dynamic
The PT-7828's built-in IP routing table can be updated and maintained both statically and dynamically. If the network is small and fixed, the network administrator can configure the IP routing table manually. If the network is extended or the network topology is changed frequently, dynamic routing can enhance network stability and reduce the time it takes to effect network convergence. Dynamic routing protocols allow devices to detect and respond to network changes automatically, making manual reconfiguration unnecessary.