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Problem with DHCP beetween subnets/VLAN in HP 2530-48G

erManue
Occasional Visitor

Problem with DHCP beetween subnets/VLAN in HP 2530-48G

0Hi:

I configured HP 2530 with 2 VLANS (VALN 2 and VLAN3).

There is a linux server acting as a router with two network interfaces (one in VLAN 2 with IP 192.168.20.1 and the other in VLAN 3 with IP 192.168..30.1). There isn´t any filtered traffic, only ip fordwarding.

 

The network address are:

 

VLAN 2 (192.168.20.0/24)

VLAN 3 (192.168.30.0/24)

 

In this scenario, everything works fine. I placed some workstations in both VLANs/subnets and there isn´t any connectivity problem.

 

Now, I configured a DHCP server placed in VLAN2 (with IP 192.168.20.200). It has two scopes:

 

SCOPE 1: 192.168.20.2 – 192.168.20.5 with default gateway 192.168.20.1 (for worksrtations in VLAN 2)

 

SCOPE 2: 192.168.30.2 – 192.168.30.5 with default gateway 192.168.30.1 (for worksrtations in VLAN 3)

 

Only workstations in VLAN 2 get address from DHCP server.

 

This is the switch configuration:

 

ip default-gateway 192.168.20.1

vlan 1

name "DEFAULT_VLAN"

no untagged 1-30

untagged 31-52

no ip address

exit

vlan 2

name "VLAN2”

untagged 1-15

ip address 192.168.20.201 255.255.255.0

exit

vlan 3

name "VLAN3"

untagged 16-30

ip address 192.168.30.201 255.255.255.0

ip helper-address 192.168.20.200

exit

 

There isn´t any connectivity problem. For example, I can ping from a workstation in VLAN 3 (static IP address 192.168.30.30) to DHCP Server (192.168.20.200) and from DHCP server (192.168.20.200) to any workstation in VLAN 3 (192.168.30.30, for example). But DHCP isn´t working for VLAN 3 (only works for VLAN 2)

 

Could someone please help me?.

 

Best Regards

 

2 REPLIES
erManue
Occasional Visitor

Re: Problem with DHCP beetween subnets/VLAN in HP 2530-48G

This is a capture with Wireshark. It seens like DHCP server gives 192.168.30.3.

No.     Time        Source                Destination           Protocol Length Info
      1 0.000000    0.0.0.0               255.255.255.255       DHCP     342    DHCP Discover - Transaction ID 0x61cd03c

Frame 1: 342 bytes on wire (2736 bits), 342 bytes captured (2736 bits)
Ethernet II, Src: DellInc_af:34:52 (00:15:c5:af:34:52), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Internet Protocol Version 4, Src: 0.0.0.0 (0.0.0.0), Dst: 255.255.255.255 (255.255.255.255)
User Datagram Protocol, Src Port: 68 (68), Dst Port: 67 (67)
Bootstrap Protocol (Discover)
    Message type: Boot Request (1)
    Hardware type: Ethernet (0x01)
    Hardware address length: 6
    Hops: 0
    Transaction ID: 0x061cd03c
    Seconds elapsed: 0
    Bootp flags: 0x0000 (Unicast)
        0... .... .... .... = Broadcast flag: Unicast
        .000 0000 0000 0000 = Reserved flags: 0x0000
    Client IP address: 0.0.0.0 (0.0.0.0)
    Your (client) IP address: 0.0.0.0 (0.0.0.0)
    Next server IP address: 0.0.0.0 (0.0.0.0)
    Relay agent IP address: 0.0.0.0 (0.0.0.0)
    Client MAC address: DellInc_af:34:52 (00:15:c5:af:34:52)
    Client hardware address padding: 00000000000000000000
    Server host name not given
    Boot file name not given
    Magic cookie: DHCP
    Option: (53) DHCP Message Type (Discover)
        Length: 1
        DHCP: Discover (1)
    Option: (116) DHCP Auto-Configuration
        Length: 1
        DHCP Auto-Configuration: AutoConfigure (1)
    Option: (61) Client identifier
        Length: 7
        Hardware type: Ethernet (0x01)
        Client MAC address: DellInc_af:34:52 (00:15:c5:af:34:52)
    Option: (50) Requested IP Address
        Length: 4
        Requested IP Address: 169.254.168.171 (169.254.168.171)
    Option: (12) Host Name
        Length: 8
        Host Name: D1MBXN2J
    Option: (60) Vendor class identifier
        Length: 8
        Vendor class identifier: MSFT 5.0
    Option: (55) Parameter Request List
        Length: 11
        Parameter Request List Item: (1) Subnet Mask
        Parameter Request List Item: (15) Domain Name
        Parameter Request List Item: (3) Router
        Parameter Request List Item: (6) Domain Name Server
        Parameter Request List Item: (44) NetBIOS over TCP/IP Name Server
        Parameter Request List Item: (46) NetBIOS over TCP/IP Node Type
        Parameter Request List Item: (47) NetBIOS over TCP/IP Scope
        Parameter Request List Item: (31) Perform Router Discover
        Parameter Request List Item: (33) Static Route
        Parameter Request List Item: (249) Private/Classless Static Route (Microsoft)
        Parameter Request List Item: (43) Vendor-Specific Information
    Option: (43) Vendor-Specific Information
        Length: 2
        Value: dc00
    Option: (255) End
        Option End: 255
    Padding

No.     Time        Source                Destination           Protocol Length Info
      2 0.001156    192.168.20.200         192.168.30.201         DHCP     342    DHCP Offer    - Transaction ID 0x61cd03c

Frame 2: 342 bytes on wire (2736 bits), 342 bytes captured (2736 bits)
Ethernet II, Src: HewlettP_16:ce:8e (00:24:81:16:ce:8e), Dst: HewlettP_0a:f1:c0 (38:63:bb:0a:f1:c0)
Internet Protocol Version 4, Src: 192.168.20.200 (192.168.20.200), Dst: 192.168.30.201 (192.168.30.201)
User Datagram Protocol, Src Port: 67 (67), Dst Port: 67 (67)
Bootstrap Protocol (Offer)
    Message type: Boot Reply (2)
    Hardware type: Ethernet (0x01)
    Hardware address length: 6
    Hops: 0
    Transaction ID: 0x061cd03c
    Seconds elapsed: 0
    Bootp flags: 0x0000 (Unicast)
        0... .... .... .... = Broadcast flag: Unicast
        .000 0000 0000 0000 = Reserved flags: 0x0000
    Client IP address: 0.0.0.0 (0.0.0.0)
    Your (client) IP address: 192.168.30.3 (192.168.30.3)
    Next server IP address: 192.168.20.200 (192.168.20.200)
    Relay agent IP address: 192.168.30.201 (192.168.30.201)
    Client MAC address: DellInc_af:34:52 (00:15:c5:af:34:52)
    Client hardware address padding: 00000000000000000000
    Server host name not given
    Boot file name not given
    Magic cookie: DHCP
    Option: (53) DHCP Message Type (Offer)
        Length: 1
        DHCP: Offer (2)
    Option: (1) Subnet Mask
        Length: 4
        Subnet Mask: 255.255.255.0 (255.255.255.0)
    Option: (58) Renewal Time Value
        Length: 4
        Renewal Time Value: (345600s) 4 days
    Option: (59) Rebinding Time Value
        Length: 4
        Rebinding Time Value: (604800s) 7 days
    Option: (51) IP Address Lease Time
        Length: 4
        IP Address Lease Time: (691200s) 8 days
    Option: (54) DHCP Server Identifier
        Length: 4
        DHCP Server Identifier: 192.168.20.200 (192.168.20.200)
    Option: (3) Router
        Length: 4
        Router: 192.168.30.1 (192.168.30.1)
    Option: (82) Agent Information Option
        Length: 12
        Option 82 Suboption: (1) Agent Circuit ID
            Length: 2
            Agent Circuit ID: 001c
        Option 82 Suboption: (2) Agent Remote ID
            Length: 6
            Agent Remote ID: 3863bb0af1c0
    Option: (255) End
        Option End: 255
    Padding

 

16again
Respected Contributor

Re: Problem with DHCP beetween subnets/VLAN in HP 2530-48G

On the relay, play around with option 82 setting.  You also might look for option so dhcp relay uses broadcast L3 address instead of offered IP address in DHCP-Offer packet header