Address recognition module
The address recognition module decides whether the packet will be received or not. Ethernet IP core starts receiving all packets regardless to their destination address. Destination address is then checked in the eth_rxaddrcheck submodule.
Frame reception depends on few conditions:
1. If r_Pro bit is set in the MODER register (Promiscuous mode), then all
frames are received regardless to their destination address. If r_Pro bit is
cleared then destination address is checked.
2. If r_Bro bit is set in the MODER register then all frames containing
broadcast addresses are rejected (r_Pro must be cleared).
3. MAC – MAC address of the used Ethernet MAC IP Core. This is
individual address of the used Ethernet core. When r_Pro bit is cleared
then every destination address is compared to the MAC address. Frame
is accepted only when two address match.
4 When r_Iam signal is set then besides checking the MAC address, hash
table algorithm is used. The Ethernet controller maps any 48-bit address
into one of 64 bits. If that bit is set in the HASH registers (HASH0 and
r_HASH1 are making one 64-bit hash register), then frame is accepted.
As said before, packet reception always starts regardless of the destination
address of the incoming packet. As soon as the destination address is received, it is checked if it matches with any of the above-mentioned conditions. If the match doesn’t occur than the reception of the whole packet is aborted (signal RxAbort is set to 1). The packet is not written to the memory and receive buffer is flushed.
The address recognition module decides whether the packet will be received or not. Ethernet IP core starts receiving all packets regardless to their destination address. Destination address is then checked in the eth_rxaddrcheck submodule.
Frame reception depends on few conditions:
1. If r_Pro bit is set in the MODER register (Promiscuous mode), then all
frames are received regardless to their destination address. If r_Pro bit is
cleared then destination address is checked.
2. If r_Bro bit is set in the MODER register then all frames containing
broadcast addresses are rejected (r_Pro must be cleared).
3. MAC – MAC address of the used Ethernet MAC IP Core. This is
individual address of the used Ethernet core. When r_Pro bit is cleared
then every destination address is compared to the MAC address. Frame
is accepted only when two address match.
4 When r_Iam signal is set then besides checking the MAC address, hash
table algorithm is used. The Ethernet controller maps any 48-bit address
into one of 64 bits. If that bit is set in the HASH registers (HASH0 and
r_HASH1 are making one 64-bit hash register), then frame is accepted.
As said before, packet reception always starts regardless of the destination
address of the incoming packet. As soon as the destination address is received, it is checked if it matches with any of the above-mentioned conditions. If the match doesn’t occur than the reception of the whole packet is aborted (signal RxAbort is set to 1). The packet is not written to the memory and receive buffer is flushed.
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