SNR S2989G-48TX-POE — настройка IP-сервисов и устранение неполадок DHCP [207/553]

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S2989G-24TX Operation Manual

Chapter 3 IP services Configuration

3-45

Switch(Config-if-Vlan1)#ip help-address 10.1.1.10

Switch(Config-if-Vlan1)#exit

Note: It is recommended to use the combination of command ip forward-protocol udp

<port> and ip helper-address <ipaddress>. ip help-address can only be configured for

ports on layer 3 and cannot be configured on layer 2 ports directly.

3.14.5

DHCP Troubleshooting

If the DHCP clients cannot obtain IP addresses and other network parameters, the

following procedures can be followed when DHCP client hardware and cables have been

verified ok.

6. Verify the DHCP server is running, start the related DHCP server if not running. If the

DHCP clients and servers are not in the same physical network, verify the router

responsible for DHCP packet forwarding has DHCP relay function. If DHCP relay is

not available for the intermediate router, it is recommended to replace the router or

upgrade its software to one that has a DHCP relay function.

7. In such case, DHCP server should be examined for an address pool that is in the

same segment of the switch VLAN, such a pool should be added if not present, and

(This does not indicate switch cannot assign IP address for different segments, see

solution 2 for details.)

8. In DHCP service, pools for dynamic IP allocation and manual binding are conflicting,

i.e., if command “network-address” and “host” are run for a pool, only one of them

will take effect; furthermore, in manual binding, only one IP-MAC binding can be

configured in one pool. If multiple bindings are required, multiple manual pools can be

created and IP-MAC bindings set for each pool. New configuration in the same pool

overwrites the previous configuration.

3.15

DHCP option 82

3.15.1

Introduction to DHCP option 82

DHCP option 82 is the Relay Agent Information Option, its option code is 82. DHCP

option 82 is aimed at strengthening the security of DHCP servers and improving the IP

address configuration policy. The Relay Agent adds option 82 (including the client’s

physical access port, the access device ID and other information), to the DHCP request