Datasheet

KSZ8863MLL/FLL/RLL
DS00002335B-page 18  2017 Microchip Technology Inc.
The lookup engine inserts the qualified SA into the table, along with the port number and time stamp. If the table is full,
the last entry of the table is deleted to make room for the new entry.
3.3.3 MIGRATION
The internal lookup engine also monitors whether a station has moved. If a station has moved, it updates the table
accordingly. Migration happens when the following conditions are met:
• The received packet’s SA is in the table, but the associated source port information is different.
• The received packet is good; the packet has no receiving errors and is of legal length.
The lookup engine updates the existing record in the table with the new source port information.
3.3.4 AGING
The lookup engine updates the time stamp information of a record whenever the corresponding SA appears. The time
stamp is used in the aging process. If a record is not updated for a period of time, the lookup engine removes the record
from the table. The lookup engine constantly performs the aging process and continuously removes aging records. The
aging period is about 200 seconds. This feature can be enabled or disabled through register 3 (0x03) bit [2].
3.3.5 FORWARDING
KSZ8863MLL/FLL/RLL forwards packets using the algorithm that is depicted in the following flowcharts. Figure 3-4
shows stage one of the forwarding algorithm, where the search engine looks up the VLAN ID, static table, and dynamic
table for the destination address, and comes up with “port to forward 1” (PTF1). PTF1 is then further modified by span-
ning tree, IGMP snooping, port mirroring, and port VLAN processes to come up with “port to forward 2” (PTF2), as
shown in Figure 3-5. The packet is sent to PTF2.
FIGURE 3-4: DESTINATION ADDRESS LOOKUP FLOW CHART, STAGE 1
Start
VLAN ID
Valid?
PTF1= NULL
Search Static
Table
Search complete.
Get PTF1 from
Static MAC Table
Dynamic Table
Search
Search complete.
Get PTF1 from
VLAN Table
Search complete.
Get PTF1 from
Dynamic MAC
Table
PTF1
- Search VLAN table
- Ingress VLAN ltering
- Discard NPVID check
YES
NO
FOUND
NOT
FOUND
FOUND
NOT
FOUND
This search is based on
DA or DA+FID
This search is based on
DA+FID