Ruijie RG-S2900G-E Series, Руководство по настройке

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Configuration Guide Access Control List Configuration
In the figure above, the meaning of each letter and the value of offset are shown below:
Letter Meaning Offset Letter Meaning Offset
A Destination MAC 0 O TTL field 34
B Source MAC 6 P Protocol ID 35
C VLAN tag field 12 Q IP checksum 36
D Data frame length field 14 R Source IP address 38
E DSAP field 18 S Destination IP address 42
F SSAP field 19 T TCP source port 46
G Ctrl field 20 U TCP destination port 48
H Org Code field 21 V Sequential number 50
I Encapsulated data type 24 W Confirmation field 54
J IP version No. 26 XY
IP header length and
reservation bits
58
K TOS field 27 Z Reservation bit and flags bit 59
L IP packet length 28 a Windows size field 60
M ID 30 b Others 62
N Flags field 32
As shown in the above table, the offset of each field is it offset in the SNAP+tag 802.3 data frame. In
the user custom access control list, the user can use two parameters, the rule mask and offset, to
abstract any byte from the first 80 bytes of the data frame, and then compare it with the user defined
rule to filter the matched data frame for corresponding processing. The user defined rule can be some
fixed attributes of the data. For example, the user wants to filter all the TCP messages by defining the
rule as “06”, rule mask as “FF” and offset as 35. Here, the rule mask and offset work together to
abstract the contents of the TCP protocol ID field in the received data frame, and compare it with the
rule to filter all TCP messages.