WATERS NETWORK SYSTEMS
™ ProSwitch
®
-
2600M User’s Manual
Page
19
DHCP Gateway Setting
The
DHCP Gateway Settings
screen provides the following information:
VLAN ID
- lists the IDs of the VLANs that have been defined.
IP Address
- displays the corresponding IP addresses of the VLANs.
DHCP Relay
– shows whether the DHCP relay is enabled or disabled.
Max Hops
-
displays the maximum number of hops that a DHCP request broadcast can be relayed
along the DHCP relay path from the DHCP client to the DHCP server.
Delay
– displays the number of seconds that must elapse before a DHCP request broadcast is relayed
to the next IP subnetwork.
Servers
- lists any preferred servers that have been defined.
Relays
-
shows the outbound IP subnetwork for relaying a DHCP request broadcast.
Note
: To specify DHCP gateway settings, you must first create a VLAN with an assigned IP address as
described in
VLAN & PVID Perspective
Section 6.0.
The following procedure describes how to change the
DHCP Gateway Settings
. You can specify up to three
preferred servers and/or an outbound relay interface.
1. Select
IP Networking
from the
Advanced Management
menu.
2. Select
DHCP Gateway Settings
.
3. Highlight the appropriate VLAN ID and press
Enter
.
4. To add a relay
IP
, press
Shift
and press
+
.
5. A setup screen will be displayed. Highlight the
appropriate interface
and press
Enter
.
6. You
can
enable/disable DHCP Gateway
, set
Maximum Hops
, set the
Delay time
(in seconds) and
specify up to
three more preferred servers
in this screen. The DHCP gateway is disabled by default.
Highlight
Disabled
and press
Enter
.
7. Select
Enabled
and press
Enter
.
8. Set
the
Maximum hops
and
Delay
time.
9. Press
Esc
to return to the appropriate menu.
This DHCP relay function allows the DHCP request being routed to the DHCP server which is in different IP
subnet on another VLAN.
About DHCP Protocol
Dynamic Host Configuration Protocol (DHCP), described in RFC 1541, is an extension of the Bootstrap Protocol
(BOOTP). DHCP allows hosts on a TCP/IP network to dynamically obtain basic configuration information. When
a DHCP client logs in, it broadcasts a DHCP Request packet, looking for DHCP servers. DHCP servers respond
to this packet with a DHCP Response packet. The client then chooses a server to obtain TCP/IP configuration
information, such as its own IP address. Since DHCP uses broadcast mechanism, a DHCP server and its client
must physically reside on the same subnet. However, it's not practical to have one DHCP server on every
subnet; in fact in many cases, DHCP/BOOTP clients and their associated DHCP/BOOTP server(s) do not reside
on the same IP network or subnet. In such cases, a third-party agent is required to transfer BOOTP messages
between clients and servers. BOOTP/DHCP Relay, described in RFC 1542, enables a host to use a BOOTP or
DHCP server to obtain basic TCP/IP configuration information, even if the servers do not reside on the local
subnet. When the 2600M with BOOTP/DHCP Relay Agent receives a DHCP Request packet destined for a
BOOTP/DHCP server, it inserts its own IP address into the DHCP Request packet so the server knows the
subnet where the client is located. Then, depending on the configuration setup, the switch will either:
Forward the packet to a specific server as defined in the switch configuration using Unicast routing
Broadcast the DHCP Request again to another directly attached IP subnet specified in the switch
