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Switch 4800G PWR 48-Port

nainasipra used Ask the Experts™
i have two switches(Switch 4800G PWR 48-Port ) and two vlans on these, both vlans getting ip from dhcp server but i connect dhcp server with one switch and connect one data cable one switch vlan to other switch vlans its not getting ip from DHCP server.
what could be the wrong configuration. or what cable should i use to connected both switches with each other.

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Since your DHCP server is in one vlan, you have to configure routing on one of the switches and on the VLAN Interface that does NOT have the DHCP server on, you have to configure a IP Helper address to forward to your DHCP server.

Do you have routing configured?  Can you send your config files for checking?
IP Helper (DHCP relay) example from the manual:

# Specify IP addresses for the interfaces (omitted).
# Enable DHCP.
<SwitchA> system-view
[SwitchA] dhcp enable
# Add DHCP server into DHCP server group 1.
[SwitchA] dhcp relay server-group 1 ip
# Enable the DHCP relay agent on VLAN-interface 1.
[SwitchA] interface vlan-interface 1
[SwitchA-Vlan-interface1] dhcp select relay
# Correlate VLAN-interface 1 to DHCP server group 1.
[SwitchA-Vlan-interface1] dhcp relay server-select 1


Dear RKinsp,

thanks for these DHCP relay config, i am sure i need this in future, but right now i am using two dhcp server for two vlans and when i connect both vlans to second switch vlans with two patch cords it should give same ip in second vlans too but its not ...., what could be the problem between the switches?


hmmm, not sure I understand, can you send over a drawing of sorts?

Anyways, between the switches if you are using different VLANs you want to configure a "trunk port" where the VLANs go through tagged.

on the interface CLI

port link-type trunk
port trunk permit vlan X


i understand RKinsp, but to configure trunk if i am using one link only between switches. as here i am using two cables for connect two vlans. i am not sure but i feel something wrong with port configuration or cable use?

cables shouldn't be a problem since the switch should correct for Crossover or straight-through automatically, regardless a switch to switch cable should be crossover (TX-RX pairs inverted on the ends).

port configuration - is you have single ports connected using a single VLAN, no it should matter, as long as they are set to the right vlan ID.

Can you ping from a computer on one switch to the other?


see i have on both switches  vlan-1(network vlan-2(network and both switches connected with two cables, one cable on each vlans port. but i could get ip from dhcp on 2nd switch.

If you could draw what you mean regarding your DHCP servers, it would be really helpful. I don't quite understand how you are connected. Do you have your switch "display current" that you can send?