MB86977 Datasheet, PDF (12/30 Pages) Fujitsu Component Limited. – IP PACKET FORWARDING ENGINE

MB86977
2. FEF Engine-header processing function
This device implements the processing of PPPoE and IPv6 over IPv4 tunnel packets through hardware.
When an input packet is one of the four types shown in the figure below, its parameters are compared with
parameters in the NAT/IP forwarding table. If one of the entries matches it, this device performs NAT/IP forwarding
after removing the PPPoE header or v6 over v4 tunnel header by hardware.
When it is required to add one of the four kinds of headers shown in the figure below after performing NAT/IP
forwarding, it is necessary for the PPPoE header field, the v4 tunnel header field, the control bit field in the NAT/
IP forwarding table to be specified appropriately. Also, the PPPoE header register or v4 tunnel header has to be
set properly.
The packet length is not checked after these headers are added. If the original packet length is long enough,
the output packet may be larger than the desired MTU of the connection. To prevent this situation, the MTU value
of the packets that will be received by this device that are transmitted by the networking device must be set
carefully.
Only IP packets can be processed by hardware. LCP and IPCP packet sent during the PPPoE discovery or
session stages are sent to the host through the host interface block.
IPv6 over IPv4
Ether header IPv4 tunnel header
IPv6 header
Data
(TCP/UDP)
CRC
IPv6 over PPPoE
Ether header PPPoE header
PPP header
IPv6 header
Data
(TCP/UDP)
CRC
IPv4 over PPPoE
Ether header PPPoE header
PPP header
IPv4 header
Data
(TCP/UDP)
CRC
IPv6 over IPv4 over PPPoE
Ether header
PPPoE
header
PPP header
IPv4 tunnel
header
IPv6 header
Data
(TCP/UDP)
CRC
Packet Formats Supported by Header Processing Function
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