RTL8309N View Datasheet(PDF) - Realtek Semiconductor

Part Name

Description

Manufacturer

RTL8309N

SINGLE-CHIP 8-PORT 10/100MBPS ETHERNET SWITCH CONTROLLER

Realtek Semiconductor 

RTL8309N

Datasheet

6.2.1. Forwarding

When the VLAN egress filtering option is enabled, a received unicast frame will be forwarded to its

destination port only if the destination port is in the same VLAN as the source port. If the destination

port belongs to a different VLAN, the frame will be discarded.

By default the received broadcast/multicast frame will flood to VLAN member ports only, except for

the source port.

IP Multicast data packets involve multicast address table lookup and forwarding operations. If the table

lookup returns a hit, the data packet is forwarded to member ports according to forwarding table setting.

If the IP multicast address is not stored in the address table (i.e., lookup miss), according to a 1-bit

action configuration the packet is dropped or flooded.

6.2.2. Learning

The RTL8309N features a Layer2 table (2K entries). It uses a 4-way hash structure to store L2 entries.

Each entry can learn in the format of L2 Unicast, and the L2 Unicast hash key is {MAC, FID}.

6.2.3. Address Table Aging

In a dynamic network topology, address aging allows the contents of the address table to always be the

most recent and correct. A learned source address entry will be cleared (aged out) if it is not updated by

the address learning process within an aging time period. The aging time of the RTL8309N is between

200 and 400 seconds (typical value is 300 seconds). The RTL8309N also supports a fast aging function

that is used to age all dynamic entries within 1ms.

6.2.4. Layer 2 Multicast

The RTL8309N supports two IP multicast frame types: IPv4 multicast and IPv6 multicast.

The RTL8309N IGMPv1/2/3 and MLDv1/2 packets can be trapped to the CPU, to allow software to

insert an IP multicast entry into the address table.

6.3. MAC Limit Function

The RTL8309N supports the capability of limiting the number of MAC addresses that are learned. The

learned MAC addresses of each port, and the total learned MAC addresses of any combination of multi

ports can be limited. The limit thresholds of each port can be configured independently.

There is a counter for each of the limits. The counter will be decremented if a counted MAC address ages

out. Deleting or creating entries in the LUT via register setting will not affect these counters. When the

8-Port 10/100M Layer2 Switch Controller

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Track ID:

Rev. 1.0

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