Is IP Helper the same as DHCP relay?
the dhcp-relay command in global config is to enable or disable the use of ip-helper to relay DHCP packets. if you disable dhcp-relay, the ip-helper command will not relay DHCP anymore, but still be able to be used as UDP forwarder for other protocols.
What is IP DHCP relay address?
The IP address of the primary DHCP relay agent receiving a client request packet is automatically added to the packet, and is identified as the giaddr (gateway interface address.) This is the IP address of the VLAN on which the request packet was received from the client.
What is DHCP relay IP Helper?
DHCP Relay essentially is the ability of a host to forward DHCP packets between clients and servers, when they reside on different subnet. ip helper-address is the cisco syntax for enabling DHCP relaying.
What is Relay Agent IP address?
Relay Agent IP address: The IP address sent by the PC (0.0. 0.0) is replaced with the downlink IP address of the DHCP relay agent (1.1. 1.254), the IP address of the relay agent’s interface at which the DHCP Discover message was received.
How do I find the DHCP relay agent?
watch for DHCP messages on the interface. when a DHCP packet arrives, set the packet’s source IP address to the IP address of Gi0/0. change the destination IP address of the packet from 255.255. 255.255 (the broadcast address) to the IP address of the DHCP server and send it to R2.
Where is DHCP relay setup?
To configure DHCP relay, from Fireware Web UI: Select Network > Interfaces….Configure DHCP Relay
- Select a trusted, optional, or custom interface and click Configure.
- From the drop-down list at the bottom of the page, select Use DHCP Relay.
- In the DHCP Server text box, type the IP address of a DHCP server and click Add.
What is DHCP relay agent command?
A DHCP relay agent uses “ip helper-address” command to indicate the DHCP server’s IP address. It will insert the IP address of the interface which has that command configured into the gateway IP address field of DHCP packet to let DHCP server know which IP address range should be used to allocate.
How do I set up a helper-address?
To configure the helper address, identify the router interface that will receive the broadcasts for UDP services. In interface configuration mode, use the ip helper-address command to define the address to which UDP broadcasts for services should be forwarded.
Where is DHCP relay configured?
Configuring DHCP relay agents We configure a DHCP relay agent only on the interface that is directly connected to a local subnet. In this network, four interfaces are directly connected to the local subnets.
How do I add a DHCP relay agent?
To add the DHCP Relay Agent, complete the following steps:
- Open the Routing And Remote Access console.
- In the console tree, right-click the General node, and then click New Routing Protocol.
- In the New Routing Protocol dialog box, click DHCP Relay Agent, and then click OK.
How configure DHCP IP Helper?
Configuring an IP helper address
- Enter the global configuration mode by issuing the configure terminal command. device# configure terminal.
- Enter the interface configuration mode.
- Add a helper address for the server.
- By default, an IP helper does not forward client broadcast requests to a server within the network.
How do I know if my DHCP relay is working?
Use the show config command (or show running for the running-config file) to display the current DHCP relay setting. NOTE: The DHCP relay and hop count increment settings appear in the show config command output only if the non-default values are configured.
How does IP Helper Work on the Nexus 7000?
IP helper (now DHCP relay) works differently on the Nexus 7000 than on the 6500. The N7K imposes a VACL to filter local DHCP broadcast traffic, under the assumption that you’d be using DHCP relay when there is no local DHCP server.
How does the relay-agent respond to a DHCP request?
DHCP server responds to the IP address of the relay-agent in the giaddr field of the discover/request packet with a DHCP offer, which is relayed to the client. DHCP client responds with DHCP request (whether it be an unicast or broadcast response), this is redirected to the relay-agent and forwarded on to the DHCP server.
What happens when a DHCP relay agent intercepts a discover packet?
When a DHCP relay agent intercepts a DISCOVER packet, the DHCP relay agent sets a any-cast address as the gateway address (giaddr) and inserts the Option-82 information in the packet, which includes the circuit ID and remote ID suboptions. The DHCP server sends the OFFER packet with the destination as giaddr.
How does the Cisco NX-OS device work with DHCP?
The Cisco NX-OS device removes the Option 82 field and forwards the packet to the interface that connects to the DHCP client that sent the DHCP request. You can configure the device to run a DHCPv6 relay agent, which forwards DHCPv6 packets between clients and servers.