Altera cyclone V Technical Reference page 1248

cv_5v4
2016.10.28
Bit
16
IHE: IP Header Error
When set, this bit indicates that the MAC transmitter detected an error in the IP datagram
header. The transmitter checks the header length in the IPv4 packet against the number of
header bytes received from the application and indicates an error status if there is a mismatch.
For IPv6 frames, a header error is reported if the main header length is not 40 bytes. Further‐
more, the Ethernet Length/​Type field value for an IPv4 or IPv6 frame must match the IPheader
version received with the packet. For IPv4 frames, an error status is also indicated if the Header
Length field has a value less than 0x5.
This bit is valid only when the Tx Checksum Offload is enabled. If COE detects an IP header
error, it still inserts an IPv4 header checksum if the Ethernet Type field indicates an IPv4
payload.
15
ES: Error Summary
Indicates the logical OR of the following bits:
■ TDES0[14]: Jabber Timeout
■ TDES0[13]: Frame Flush
■ TDES0[11]: Loss of Carrier
■ TDES0[10]: No Carrier
■ TDES0[9]: Late Collision
■ TDES0[8]: Excessive Collision
■ TDES0[2]: Excessive Deferral
■ TDES0[1]: Underflow Error
■ TDES0[16]: IP Header Error
■ TDES0[12]: IP Payload Error
14
JT: Jabber Timeout
When set, this bit indicates the MAC transmitter has experienced a jabber time-out. This bit is
only set when Bit 22 (Jabber Disable) of Register 0 (MAC Configuration Register) is not set.
13
FF: Frame Flushed
When set, this bit indicates that the DMA or MTL flushed the frame because of a software
Flush command given by the CPU.
12
IPE: IP Payload Error
When set, this bit indicates that MAC transmitter detected an error in the TCP, UDP, or ICMP
IP datagram payload. The transmitter checks the payload length received in the IPv4 or IPv6
header against the actual number of TCP, UDP, or ICMP packet bytes received from the
application and issues an error status in case of a mismatch.
Ethernet Media Access Controller
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Description
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17-33
Transmit Descriptor
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