D-Link Xstack DES-3528 Series Reference Manual page 361

xStack® DES-3528/DES-3552 Series Layer 2 Managed Stackable Fast Ethernet Switch Web UI Reference Guide
2. The switch will deny all other ARP packets which claim they are from the gateway's IP.
The design of Packet Content ACL on the Switch enables users to inspect any offset chunk. An offset chunk is a 4-
byte block in a HEX format, which is utilized to match the individual field in an Ethernet frame. Each profile is
allowed to contain up to a maximum of four offset chunks. Furthermore, only one single profile of Packet Content
ACL can be supported per switch. In other words, up to 16 bytes of total offset chunks can be applied to each
profile and a switch. Therefore, a careful consideration is needed for planning and configuration of the valuable
offset chunks.
In Table 6, you will notice that the Offset_Chunk0 starts from the 127th byte and ends at the 128th byte. It also can
be found that the offset chunk is scratched from 1 but not zero.
Offset Offset Offset Offset
Chunk Chunk0 Chunk1 Chunk2
127 3 7
Byte
128 4 8
Byte
1 5 9
Byte
2 6 10
Byte
Offset Offset Offset Offset
Chunk Chunk16 Chunk17 Chunk18
63 67 71
Byte
64 68 72
Byte
65 69 73
Byte
66 70 74
Byte
The following table indicates a completed ARP packet contained in Ethernet frame which is the pattern for the
calculation of packet offset.
Table 5 A Completed ARP Packet Contained in an Ethernet Frame
Command
Step 1: create access_profile profile_id 1
profile_name 1 ethernet source_mac FF-
FF-FF-FF-FF-FF ethernet_type
Step 2: config access_profile profile_id 1 add
access_id 1 ethernet source_mac 01-02-
03-04-05-06 ethernet_type 0x806 port 1-
12 permit
create access_profile profile_id 2
Step 3:
profile_name 2 packet_content_mask
Offset Offset Offset Offset
Chunk3 Chunk4 Chunk5 Chunk6
11 15 19 23
12 16 20 24
13 17 21 25
14 18 22 26
Offset Offset Offset Offset
Chunk19 Chunk20 Chunk21 Chunk22
75 79 83 87
76 80 84 88
77 81 85 89
78 82 86 90
Table 6. Chunk and Packet Offset
Offset Offset Offset Offset
Chunk7 Chunk8 Chunk9 Chunk10
27 31 35 39
28 32 36 40
29 33 37 41
30 34 38 42
Offset Offset Offset Offset
Chunk23 Chunk24 Chunk25 Chunk26
91 95 99 103
92 96 100 104
93 97 101 105
94 98 102 106
Description
Create access profile 1 to match Ethernet Type and
Source MAC address.
Configure access profile 1
Only if the gateway's ARP packet that contains the
correct Source MAC in the Ethernet frame can pass
through the switch.
Create access profile 2
354
Offset Offset Offset Offset
Chunk11 Chunk12 Chunk13 Chunk14
43 47 51
44 48 52
45 49 53
46 50 54
Offset Offset Offset
Chunk27 Chunk28 Chunk29 Chunk30
107 111 115
108 112 116
109 113 117
110 114 118
Offset
Chunk15
55 59
56 60
57 61
58 62
Offset Offset
Chunk31
119 123
120 124
121 125
122 126