topic Re: DHCP Relay issue with 5420F-24S-4XE switch in ExtremeSwitching (EXOS/Switch Engine)

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

WAJDI-S — Tue, 11 Jun 2024 09:52:38 GMT

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

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

Stefan_K_ — Tue, 11 Jun 2024 13:26:02 GMT

IP-Forwarding enabled on the VLANs?
DHCP Relay enabled on both VLANs (Client- + Server-VLAN)?

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

Gabriel_G — Tue, 11 Jun 2024 13:53:25 GMT

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

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

WAJDI-S — Wed, 12 Jun 2024 09:59:06 GMT

thank you for reply ,

IP forwarding is enabled

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

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

Stefan_K_ — Wed, 12 Jun 2024 10:36:48 GMT

Can you share the output of:

show configuration nettools

show bootprelay

show bootprelay configuration

Can you ping the DHCP-Server from the switch?

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

WAJDI-S — Wed, 12 Jun 2024 12:45:06 GMT

# 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

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

Stefan_K_ — Wed, 12 Jun 2024 13:32:34 GMT

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

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

WAJDI-S — Wed, 12 Jun 2024 13:54:52 GMT

#show bootprelay
Bootprelay : Disabled on virtual router "VR-Default", but enabled on some VLANs
Include Secondary : Disabled
DHCP Relay Agent Information Option : Enabled on virtual router "VR-Default"
DHCP Relay Agent Information Check : Enabled on virtual router "VR-Default"
DHCP Relay Agent Information Policy : Replace
DHCP Relay Agent Information Remote-ID : "default"

DHCP/BOOTP relay statistics for virtual router "VR-Default"
Received from client = 49420 Received from server = 660
Requests relayed = 942 Responses relayed = 660
DHCP Discover = 48993 DHCP Offer = 293
DHCP Request = 379 DHCP Ack = 362
DHCP Decline = 0 DHCP NAck = 5
DHCP Release = 0
DHCP Inform = 48

DHCP Information Option 82 packets statistics for virtual router "VR-Default"
Received from client = 0 Received from server = 507
Requests replaced = 0 Responses dropped = 0
Opt82 added to Requests = 678

Note: Default Remote-ID : System MAC Address