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Seadog's avatar
Seadog
Icon for Occasional Contributor rankOccasional Contributor
5 years ago

Clarification of documentation for Align Packet Headers to 32-bit Boundaries option in TS-Ethernet

The Triple Speed Ethernet MAC core (UG-01008, 3/29/2019) has a feature which provides alignment of IP headers on 32-bit boundaries by inserting a 2-byte pad of 0x0000 at the beginning of the packet. ...
SengKok_L_Intel's avatar
SengKok_L_Intel
Icon for Regular Contributor rankRegular Contributor
5 years ago

Just to add on:

At the Avalon ST interface of TSE IP, the client frame is starting with the destination address (6 bytes), followed by the source address (6 bytes), Type/Length(2 bytes), and then Payload.

Without 32 bits alignment

  • First 32 bits = destination address (6 bytes) + source address (2 bytes)
  • Second 32 bits = source address(4 bytes) + Type Length (2 bytes) + Payload (2 bytes)

With 32 bits alignment

  • First 32 bits = Zero (2 bytes) + destination address (6 bytes)
  • Second 32 bits = source address (6 bytes) + Type Length (2 bytes)
  • Third 32 bits = payload (8 bytes)