IES-1248-51 User’s Guide
Chapter 27 DHCP Relay
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H A P T E R
27
DHCP Relay
This chapter shows you how to set up DHCP relays for each VLAN.
27.1 DHCP Relay
DHCP (Dynamic Host Configuration Protocol, RFC 2131 and RFC 2132) allows individual
clients to obtain TCP/IP configuration at start-up from a DHCP server. You can configure the
IES-1248-51 to relay DHCP requests to one or more DHCP servers and the server’s responses
back to the clients. You can specify default DHCP servers for all VLAN, and you can specify
DHCP servers for each VLAN.
27.2 DHCP Relay Agent Information Option (Option 82)
The IES-1248-51 can add information to DHCP requests that it relays to a DHCP server. This
helps provide authentication about the source of the requests. You can also specify additional
information for the IES-1248-51 to add to the DHCP requests that it relays to the DHCP
server. Please see RFC 3046 for more details.
27.2.1 DHCP Relay Agent Circuit ID and Remote ID Sub-option
Formats
The DHCP relay agent information feature adds an Agent Information field to the option 82
field of the DHCP headers of DHCP request frames that the IES-1248-51 relays to a DHCP
server. The Agent Information field that the IES-1248-51 adds contains an “Agent Circuit-ID
sub-option” that includes the port number, VLAN ID and optional information about the port
where the DHCP request was received.
The following figure shows the format of the Agent Circuit ID sub-option. The 1 in the first
field identifies this as an Agent Circuit ID sub-option. The length N gives the total number of
octets in the Agent Information Field. If the configuration request was received on a DSL port,
a 2-byte Port No field specifies the ingress port number (the first byte is always 0, the second
byte is 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 0 to 24 bytes and is optional information
(that you specify) about this relay agent.
Figure 89
DHCP Relay Agent Circuit ID Sub-option Format
Summary of Contents for IES-1248-51
Page 1: ...IES 1248 51 ADSL2 IP DSLAM User s Guide Version 3 51 ABQ 1 3 2006 ...
Page 4: ...IES 1248 51 User s Guide 4 Interference Statements and Warnings ...
Page 22: ...IES 1248 51 User s Guide 22 Table of Contents Index 379 ...
Page 30: ...IES 1248 51 User s Guide 30 List of Figures ...
Page 34: ...IES 1248 51 User s Guide 34 List of Tables ...
Page 48: ...IES 1248 51 User s Guide 48 Chapter 2 Hardware Installation ...
Page 62: ...IES 1248 51 User s Guide 62 Chapter 4 MDF Connections ...
Page 73: ...IES 1248 51 User s Guide Chapter 7 Introducing the Web Configurator 73 Figure 29 Logout ...
Page 74: ...IES 1248 51 User s Guide 74 Chapter 7 Introducing the Web Configurator ...
Page 88: ...IES 1248 51 User s Guide 88 Chapter 9 Home and Port Statistics Screens ...
Page 90: ...IES 1248 51 User s Guide 90 Chapter 10 System Information Figure 44 System Info ...
Page 98: ...IES 1248 51 User s Guide 98 Chapter 12 User Account ...
Page 104: ...IES 1248 51 User s Guide 104 Chapter 13 Switch Setup ...
Page 106: ...IES 1248 51 User s Guide 106 Chapter 14 IP Setup ...
Page 126: ...IES 1248 51 User s Guide 126 Chapter 16 xDSL Port Setup ...
Page 140: ...IES 1248 51 User s Guide 140 Chapter 17 xDSL Profiles Setup ...
Page 154: ...IES 1248 51 User s Guide 154 Chapter 19 VLAN ...
Page 188: ...IES 1248 51 User s Guide 188 Chapter 28 2684 Routed Mode ...
Page 192: ...IES 1248 51 User s Guide 192 Chapter 30 Syslog ...
Page 210: ...IES 1248 51 User s Guide 210 Chapter 33 Alarm ...
Page 240: ...IES 1248 51 User s Guide 240 Chapter 38 Commands ...
Page 256: ...IES 1248 51 User s Guide 256 Chapter 40 Alarm Commands ...
Page 262: ...IES 1248 51 User s Guide 262 Chapter 41 DHCP Relay Commands ...
Page 282: ...IES 1248 51 User s Guide 282 Chapter 44 IGMP Commands ...
Page 286: ...IES 1248 51 User s Guide 286 Chapter 45 Packet Filter Commands ...
Page 292: ...IES 1248 51 User s Guide 292 Chapter 46 IP Commands ...
Page 302: ...IES 1248 51 User s Guide 302 Chapter 48 SNMP ...
Page 338: ...IES 1248 51 User s Guide 338 Chapter 49 ADSL Commands ...
Page 358: ...IES 1248 51 User s Guide 358 Chapter 50 Virtual Channel Management ...
Page 370: ...IES 1248 51 User s Guide 370 Chapter 51 Troubleshooting ...
Page 378: ...IES 1248 51 User s Guide 378 ...