Extreme Networks

WAJDI-S · a week ago

Hi all,

I have recently migrated two switch extreme network 5420F-24S-4XE in Stack for our customer,
I have encountered an issue concerning DHCP functionality,

Specifically,Although DHCP Relay has been enabled on the switches ,DHCP client are unable to obtain an IP address.

It is pertinent to mention that our client had been utilizing a Cisco switches for several years prior to this transition and without having any problem with DHCP

please note that I have verified that the configuration is configured correctly, from the switch and from the DHCP server side,

I tried to capture the traffic using wire shark , the traffic stop in the switch ,

we request your assistance for this problem, given the critical nature of the DHCP service in the network

thank you for return

Gabriel_G · a week ago

As Stefan mentioned:

Most Cisco folks forget to enable DHCP-Relay and IP-Forwarding on the VLAN in the direction of the DHCP server (rtlookup <DHCP Server IP>).

Be sure that you've enabled both bootprelay and IP Forwarding on the server VLAN.

https://extreme-networks.my.site.com/ExtrArticleDetail?an=000083193

View solution in original post

WAJDI-S · Wednesday

thank you for reply ,

IP forwarding is enabled

dhcp relay is enabled too on both vlans (client + server)

Stefan_K_ · Wednesday

Can you share the output of:

show configuration nettools

show bootprelay

show bootprelay configuration

Can you ping the DHCP-Server from the switch?

WAJDI-S · Wednesday

# Module netTools configuration.:

enable bootprelay ipv4 vlan server
enable bootprelay ipv4 vlan user
configure bootprelay vlan user add 10.X.X.252(server IP)

show bootprelay configuration
DHCPv4 BOOTP Relay : Disabled on virtual router "VR-Default", but enabled on sos
Include Secondary : Disabled
BOOTP Relay Servers :
DHCP Relay Agent Information Option: Disabled
DHCP Relay Agent Information Check : Disabled
DHCP Relay Agent Information Policy: Replace
DHCP Relay Agent Source VLAN : None

VLAN DHCPv4 BOOTP Relay
------------------------ ------------------
VLAN "Default":
BOOTP Relay : Disabled
VLAN "user":
BOOTP Relay : Enabled
BOOTP Relay Servers : 10.10.0.252
DHCP Relay Agent Information Option: Disabled
DHCP Relay Agent Information Check : Disabled
DHCP Relay Agent Information Policy: Replace
VLAN "server":
BOOTP Relay : Enabled

please note : if I configure a PC with a static IP , I can ping the rest of the network and the DHCP server

Stefan_K_ · Wednesday

This looks good I think. I'm still curious about the "show bootprelay" command as this shows statistics, e.g.:

DHCP/BOOTP relay statistics for virtual router "VR-Default"
    Received from client =      63559  Received from server =      61023
    Requests relayed     =     190677  Responses relayed    =      61023
    DHCP Discover        =      10855  DHCP Offer           =       8857
    DHCP Request         =      51498  DHCP Ack             =      49729
    DHCP Decline         =         11  DHCP NAck            =       2437
    DHCP Release         =          3
    DHCP Inform          =       1192

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DHCP Relay issue with 5420F-24S-4XE switch

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