Monday, February 6, 2012

DHCP Relay

Dynamic Host Configuration Protocol (DHCP) serves to provide configuration parameters in a client/server environment where the DHCP server maintain address pool and lease information which the server used at time of requesting for IP from client side. This concept of DHCP relay is used when client and server does not reside on the same subnet. Look at the figure below; where the DHCP relay agent acts as a middle-man between host and DHCP server. When the host boots up on the network, the DHCP lease process occurs between the DHCP server and host (client).

DHCP lease process involves the following steps:

In this step the host (client) sends a broadcast message over the network to request for IP address lease. The DHCP relay agent forwards the request to DHCP server after receiving from host.

This can be a response from different server. This includes configuration parameters like IP, Lease information, MAC address, domain name etc as a unicast message to the host (client)

This is in response from the DHCP server to client who sends the initial DHCP server request, message means the client is requesting for IP address lease.

This is sent by DHCP server to DHCP client which is the confirmation of assigning IP lease to the client.

As DHCPDISCOVER message is a broadcast over the network and you need a proper routing to route this message across the other segments where it has to be routed. For this you need to configure this on router interface so that it can forward your request to your DHCP server.

NOTE: In a routed network, you would need DHCP Relay Agents if you plan to implement only one DHCP server.

All clients on a network should be able to contact DHCP server. For this your server should be on the network topology and relied on by all TCP/IP based hosts with your environment. If your network is composed of different segments then we have to perform any of the following tasks:

a) Place a DHCP Relay agent on each segment
b) Place a DHCP server on each segment
c) Configure your router to forward a broadcast message

Configuration on Router


You just need to configure a single command under the interface

[HUAWEI] interface GigabitEthernet 1/0/1
[HUAWEI-GigabitEthernet1/0/1] dhcp select {global | interface | relay}
[HUAWEI-GigabitEthernet1/0/1] dhcp select relay
[HUAWEI-GigabitEthernet1/0/1] ip relay address


display dhcp relay statistics
display dhcp relay server {all | interface | vlan}


Router # ip dhcp relay enable
Router # ip dhcp relay server //Specify DHCP server address


Router# show ip dhcp relay conf
Router# show ip dhcp relay statistics

I Hope this will be informative for you :)


Wasim Akram said...

Thanks Sohail bai for sharing such type of valuable materials with the poor people like us.

Fghkfhk Dfgaert said...

prada sunglasses
barcelona jersey
canada goose jackets
coach outlet online
basketball shoes
five fingers shoes
air huarache
coach outlet
polo ralph lauren
kevin durant shoes

Stjsrty Xtjsrty said...

vibram fivefingers shoes
oakley sunglasses
christian louboutin shoes
converse trainers
air jordan 4
nike factory outlet
mlb shop
red bottom shoes
ugg boots on sale 70% off

miki said...

0813jejeÀ l'heure nike jordan pas cher livraison gratuite actuelle, beaucoup de gens ont vu les publicités à la adidas zx flux noir et cuivre femme télévision avec le Jupiter Jack. Même ainsi, tous asics gel lyte 5 beige rouge ne seront pas en mesure d'offrir des avantages air jordan 9 anthracite nike efficaces à leurs citoyens. Les deux chaussures Air Jordan Reveal Chaussures utilisent un caoutchouc solide à chevrons dans la semelle extérieure.
nike air jordan 2017 Je vais adidas zx flux gris bleu utiliser la 3ème définition Nike Shox air jordan 1 dunk Navina, caractérisée par l'originalité et asics gel lyte v speckle noir l'expressivité. Source de l'article: basket nike air max bw femme est souvent un moyen basket nike femme blanche et grise sain d'obtenir un soulagement nike men's air jordan du pied et de asics gel kinsei 5 Baskets réduire l'arthrite. Les baskets de basket nike air max 1 mid basket-ball plus chers que Nike chaussures nike femme presto fait utiliser ces mêmes technologies.