How to change the DHCP relay/helper on H3C S5800 Series switch ?

[Server-Support]

Hi Eric,

I can now login to the switch after getting the correct credentials, so this is the result of the current configuration:

<CORE-SWITCH01>
<CORE-SWITCH01>display dhcp relay all
    Interface name                                  Server-group
    Vlan-interface4                                       1
    Vlan-interface5                                       1
    Vlan-interface8                                       1
    Vlan-interface18                                      1
    Vlan-interface61                                      1
<CORE-SWITCH01>

[Server-Support]

Which means the command would be:

<CORE-SWITCH01>dhcp relay server-group 1 ip 10.1.3.196

Then remove the old server:

<CORE-SWITCH01>undo dhcp relay server-group 1 ip 10.1.3.2

Would that be correct two lines that I can execute or is that wrong ?

[Server-Support]

The full configuration dump can be located in the attached text file for more information.

The below code is just the snippet of the first few lines of the display running-config command:

******************************************************************************
* Copyright (c) 2004-2011 Hangzhou H3C Tech. Co., Ltd. All rights reserved.  *
* Without the owner's prior written consent,                                 *
* no decompiling or reverse-engineering shall be allowed.                    *
******************************************************************************

User interface aux0 is available.

Please press ENTER.

Login authentication

<CORE-SWITCH01>display current-configuration
#
 version 5.20, Release 1211
#
 sysname CORE-SWITCH01
#
 clock timezone #Web#10#02 add 10:00:00
#
 super password level 3 cipher ISqbSaL!#%&#@!!!
#
 dhcp relay server-group 1 ip 10.1.3.2
#
 irf domain 2
 irf mac-address persistent timer
 irf auto-update enable
 undo irf link-delay
 irf member 1 priority 32
 irf member 2 priority 31
#
 domain default enable system

.......

skip few hundred lines

.......

#
interface Ten-GigabitEthernet1/0/27
#
interface Ten-GigabitEthernet1/0/28
#
interface Ten-GigabitEthernet2/0/27
#
interface Ten-GigabitEthernet2/0/28
#
ospf 100 router-id 10.1.1.3
 silent-interface Vlan-interface2
 silent-interface Vlan-interface4
 silent-interface Vlan-interface5
 silent-interface Vlan-interface6
 silent-interface Vlan-interface8
 silent-interface Vlan-interface18
 area 0.0.0.0
  network 10.1.0.0 0.0.255.255
#
 dhcp enable
#
 ntp-service source-interface Vlan-interface2
 ntp-service unicast-server 10.1.3.26
#
 ssh server enable
#
 undo arp check enable
#
 load xml-configuration
#
 load tr069-configuration
#
user-interface aux 0 1
 authentication-mode scheme
user-interface vty 0 15
 authentication-mode scheme
#
irf-port 1/2
 port group interface Ten-GigabitEthernet1/0/27 mode enhanced
 port group interface Ten-GigabitEthernet1/0/28 mode enhanced
#
irf-port 2/1
 port group interface Ten-GigabitEthernet2/0/27 mode enhanced
 port group interface Ten-GigabitEthernet2/0/28 mode enhanced
#
return
<CORE-SWITCH01>

[EricAtHP]

You got it.

Good luck!

[Server-Support]

Hi Eric,

Since my H3C switch is configured as stacked and I only connected to the Switch #1 on COM1 serial port, do I need to do the same thing on the second switch for changing the DHCP relay setting ?

or that two lines of command is enough ?

[EricAtHP]

No, in IRF, both switches are logically one switch. Technically, the management processes of one switch is managing the whole stack.

In fact, if you want to play a little, keep the serial console session up that you have right now and then connect a second serial console to the other switch and connect. You will see a message indicating that you connected on the first connection and have exactly the same context.

[Server-Support]

Many thanks Eric.

Hopefully tomorrow over the weekend I can implement the changes on the DHCP relay without any issue or outage caused from the Putty session remotely.

[Server-Support]

Hi Eric,

Somehow I also amanged to found the IP address for the Web Management Platform for this H3C S5800 switch, therefore I can open it from old Windows Server with IE8 and go to Network | DHCP | DHCP Relay tab

is there any difference making the changes from the web console above compare with the COM1 serial port ?

I assume that in the IRF mode this change should only be done once either way (Web GUI or Putty COnsole).

[EricAtHP]

There is no difference between the web and CLI. That said, I have never used the web interface on that switch. You will find that many of the configuration options that are availble in the CLI don't exist in the web interface.

[jbutler1946]

     Looking for some additional help with the DHCP Relay on an HP A7510 Switch.  I had a relay group pointing to an older dhcp server. I changed the relay group on vlan 20 to relay group 3 (New 2012 DHCP Servers, and for testing purposes I even made relay group 4 (Single DHCP Server). Vlan20 was using the old server on relay group 2, after changing the server-group 3 devices are still pulling fron the old dhcp server group. I tried removing server group 2 completely and even rebooted the switch. No matter what I do vlan 20 will not use the new DHCP server. Maybe I'm missing something. See DHCP relay info below.

Thank You in advance for the help.

dhcp relay server-group 3 ip 10.2.50.7
dhcp relay server-group 3 ip 10.2.50.8
dhcp relay server-group 3 ip 10.2.50.248
dhcp relay server-group 4 ip 10.2.50.8

interface Vlan-interface2
ip address 10.2.1.1 255.255.0.0
#
interface Vlan-interface3
ip address 10.3.1.1 255.255.0.0
#
interface Vlan-interface5
ip address 10.5.0.2 255.255.255.252
#
interface Vlan-interface6
ip address 10.6.1.1 255.255.0.0
#
interface Vlan-interface20
ip address 10.20.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface30
ip address 10.31.1.1 255.255.0.0
#
interface Vlan-interface40
ip address 10.40.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface50
ip address 10.50.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface60
ip address 10.60.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface61
ip address 10.61.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface71
ip address 10.71.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface100
ip address 10.100.255.254 255.255.0.0
#
interface Vlan-interface200
ip address 10.200.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface220
ip address 10.220.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface230
ip address 10.230.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface240
ip address 10.240.255.254 255.255.0.0
#
interface Vlan-interface241
ip address 10.241.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 3
#
interface Vlan-interface250
ip address 10.250.255.254 255.255.0.0
#
interface Vlan-interface251
ip address 10.251.255.254 255.255.0.0
dhcp select relay
dhcp relay server-select 4
#
interface Vlan-interface601
ip address 172.16.1.254 255.255.255.0
#
interface Vlan-interface701
ip address 172.16.2.254 255.255.255.0