ZyXEL Communications SAM1316-22, User Manual

Page: 184 / 464

Chapter 26 DHCP Relay
SAM1316-22 User’s Guide
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specifies the ingress slot number, and a 1-byte Port No field specifies the ingress
port number (both in hexadecimal format). The next field is 2 bytes and displays
the DHCP request packet’s VLAN ID. The last field (A) can range from 1 to 24
bytes (including a one-byte termination character) and is optional information
(that you specify) about this relay agent.
The Agent Information field that the SAM1316-22 adds also contains an “Agent
Remote-ID sub-option” of information that you specify.
The following table shows the format of the private Agent Remote ID sub-option.
The “2” in the first field identifies this as an Agent Remote ID sub-option. The
length N gives the total number of octets in the Agent Information Field. Then
there is the port number (in plain text format) upon which the DHCP client request
was received. Next, the extra information field (A in the table) contains from 0 to
23 bytes of optional information (that you specify) with no spaces and no
termination character (if you do not specify any information, this field contains no
data). This is followed by a slash (/), the port name, a slash (/) and the telephony
port.
26.2.2 TR-101 Format
The Agent Information field that the management switch card adds contains an
“Agent Circuit-ID sub-option” that includes the system name or IP address, slot
ID, port number, VPI, and VCI on which the TCP/IP configuration request was
received.
The following figure shows the format of the TR-101 Agent Circuit ID sub-option.
The 1 in the first field identifies this as an Agent Circuit ID sub-option. The next
field specifies the length of the field. The hostname field displays the system
name, if it has been configured, the extra information field (A) if the hostname
was not configured, or the IP address in dotted decimal notation (w.x.y.z), if
neither the system name nor the extra information field was been configured. In
either case, the hostname is truncated to 23 characters, and trailing spaces are
discarded. The hostname field is followed by a space, the string “atm”, and
another space. Then, a 1-byte Slot ID field specifies the ingress slot number, and a
1-byte Port No field specifies the ingress port number. Next, the VPI and VCI
denote the virtual circuit that received the DHCP request message from the
subscriber. If the VID is turned on, there is a colon and then the VLAN ID (1 ~
4094). If the VID is turned off, there is neither colon nor VID.
Table 56 DHCP Relay Agent Circuit ID Sub-option Format: Private
1 N Slot No Port No VLAN ID A
Table 57 DHCP Relay Agent Remote ID Sub-option Format: Private
2 N Port Number / A / Port Name / Port Tel