Endace DAG 5.2X, Руководство пользователя

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EDM01-33v1 DAG_7.5G4_Card_User_Guide
©2008 Endace Technology Ltd. Confidential - Version 1 - November 2008 57
ERF 16. TYPE_DSM_COLOR_ETH
Type Bit 7 1 = Extension header present. See Extension Headers 58 (page ).
Bits 6:0 Type 16
Short description TYPE_DSM_COLOR_ETH
Long description Type 16 DSM Color Ethernet Record
Use This record format is for Ethernet [802.3] data links, incorporating filter results. The
record format is the same type as the Type 2 TYPE_ETH 56 (page ) record, with the
exception that the lctr field reassigned as DSM type color.
The
TYPE_DSM_COLOR_ETH
record is shown below:
The following is a description of the
TYPE_DSM_COLOR_ETH
record format:
Field Description
Color
(2 bytes)
The color field is a hardware generated tag indicating the result of a filtering or
classification operation.
This field is divided into the following:
Bit Description
0-5 Receive stream number (0-63)
6-13 Filter match bits (bit6 = filter0, bit7 = filter1 and so on).
14 hlb0 (CRC calculation) output bit.
15 hlb1 (parity calculation) output bit.
Offset
(1 byte)
Number of bytes not captured from the start of the frame. This is typically used to
skip link layer headers when they are not required in order to save bandwidth and
space.
Note: This field is currently not implemented; contents should be disregarded.
Pad
(1 byte)
The Ethernet frame begins immediately after the pad byte so that the layer 3 [IP]
header is 32-bit aligned. This is typically used to skip link layer headers when they are
not required in order to save bandwidth and space.
Payload
(bytes of record)
Payload = rlen - ERF header (16 bytes) - Extension headers (optional)
- Padding (2 bytes)
Note: Because both the Type-2 and Type-16 Ethernet record header occupies 18 bytes
instead of the standard 16 bytes, any payload captured will always be 2 bytes less
than the
slen
value i.e. a
slen
of 48 which will produce a 64 byte record made up of
18 bytes of header and 46 bytes of payload.
Because the
slen
value must always be a multiple of 8, this means that if you wish
to capture 48 bytes of payload for instance, the
slen
must to set to 56.