KSZ8842-PMBLAM MICREL [Micrel Semiconductor], KSZ8842-PMBLAM Datasheet - Page 27

• Manufacturer Part Number: KSZ8842-PMBLAM
• Description: 2-Port Ethernet Switch with PCI Interface
• Manufacturer: MICREL [Micrel Semiconductor]

Micrel, Inc.
The KSZ8842-PMQL/PMBL will not forward the following packets:
Switching Engine
The KSZ8842-PMQL/PMBL features a high-performance switching engine to move data to and from the MAC’s packet
buffers. It operates in store and forward mode, while the efficient switching mechanism reduces overall latency.
The switching engine has a 32KB internal frame buffer. This resource is shared between all the ports. There are a total
of 256 buffers available. Each buffer is sized at 128B.
October 2007
1. Error packets.
2. 802.3x pause frames.
3. "Local" packets.
These include framing errors, Frame Check Sequence (FCS) errors, alignment errors, and illegal size packet
errors.
The KSZ8842-PMQL/PMBL intercepts these packets and performs flow control.
Based on destination address (DA) lookup. If the destination port from the lookup table matches the port from
which the packet originated, the packet is defined as "local."
Figure 8. Destination Address Resolution Flow Chart, Stage 2
Spanning Tree
IGMP Process
Membership
Port Mirror
Port VLAN
Process
Process
Check
PTF1
PTF2
- Check receiving port's receive enable bit
- Check destination port's transmit enable bit
- Check whether packets are special (BPDU)
or specified
- Applied to MAC #1 and MAC #2
- IGMP will be forwarded to the host port
- RX Mirror
- TX Mirror
- RX or TX Mirror
- RX and TX Mirror
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KSZ8842-PMQL/PMBL
M9999-100207-1.5