Can terminals connected to S series switches obtain IP addresses through DHCP

3

For S series switches excluding the S1700, terminals connected to switches (enabled to obtain IP addresses through DHCP) can obtain IP addresses through DHCP when either of the following conditions is met:
- The switch is configured with the DHCP server function. (By default, a switch is not configured with the DHCP server function.)
- Another DHCP server is deployed on the network and there is a reachable route from the terminal to the DHCP server.

Other related questions:
Can clients connected to S series switch obtain IP addresses through DHCP
DHCP-enabled terminals that are connected to S series switches except S1700 switches can obtain IP addresses from DHCP servers when either of the following conditions is met: - The DHCP server function has been enabled on the switches. (By default, the DHCP server function is disabled on a switch.) - A DHCP server is available on the network and reachable to the terminals.

Can a downstream terminal connected to an AR obtain an IP address through DHCP
A downstream terminal connected to the AR obtain an IP address through DHCP in either of the following situations: - The AR is configured with the DHCP server function. By default, an AR is not configured with the DHCP server function. - Another DHCP server exists on the network and there is a reachable route from the terminal to the DHCP server. Otherwise, the downstream terminal connected to the AR cannot obtain an IP address through DHCP.

Types of packets checked by S series switches with IPSG enabled
For S series switches (except S1700 switches), IPSG takes effect only for IP packets (except DHCP packets) but not for packets of other types such as ARP or PPPoE. With IPSG enabled, an S series switch checks only IPv4 packets in versions earlier than V200R001 and checks all IPv4 and IPv6 packets in V200R001 and later versions.

Intranet users can only obtain IP addresses through DHCP for Internet access on S series switches
Intranet users can only obtain IP addresses through DHCP for Internet access on S series switches excluding the S1700. The configuration procedure is as follows: 1. Configure a switch as the DHCP server. For details 2. Configure DHCP snooping. See the following DHCP snooping configuration. [HUAWEI] dhcp snooping enable [HUAWEI] interface GigabitEthernet2/0/0 //Enable the Layer 3 interface that is automatically assigned an IP address. [HUAWEI-GigabitEthernet2/0/0] dhcp snooping trusted //Configure the interface as the trusted interface. [HUAWEI-GigabitEthernet2/0/0] dhcp snooping enable //Enable DHCP snooping. [HUAWEI-GigabitEthernet2/0/0] ip source check user-bind enable //To prevent IP packets of unauthorized users from entering the external network through the switch, you can enable the IP packet check function on an interface or in a VLAN. After the IP packet check function is enabled, only the IP packets matching entries in the binding table are forwarded. After DHCP snooping is enabled, a dynamic binding table is generated. [HUAWEI-GigabitEthernet2/0/0] arp anti-attack check user-bind enable //After ARP packet check is enabled, the switch checks all the ARP packets passing through an interface or a VLAN against the binding table. Only the ARP packets matching the binding table are forwarded. [HUAWEI-GigabitEthernet2/0/0] quit [HUAWEI] user-bind static ip-address 10.0.0.1 mac-address 0001-0001-0001 //If users want to configure static IP addresses for Internet access, a static binding table must be configured.

Causes for PCs obtain the same IP address through the S series switch
The S series switch is used as the DHCP server to assign IP addresses to PCs: 1. If a DHCP client connects to a network again, the DHCP client broadcasts a DHCP Request packet carrying the IP address that the client has used. The used IP address is added in the Option50 field of packets. After receiving the DHCP Request message, the DHCP server checks whether the lease record exists based on the MAC address in the message. If so, the DHCP server replies with a DHCP ACK message to notify the DHCP client that the requested IP address can be used. If not, the DHCP server waits for a new DHCP Discover message from the client.

If you have more questions, you can seek help from following ways:
To iKnow To Live Chat
Scroll to top