DHCP issue IOS-XE 9300

[medharrak]

I have an issue with DHCP in  IOS-XE C9300 version 17.03.03.

VLANs are configured with ip-helper-address X.X.X.X, the configuration was working fine in the old switch C3850, But now clients take a long time to get an ip address , and sometimes  they disconnect.

Any idea what should be an issue?

[MHM Cisco World · Accepted solution]

because the Queue is share between the ICMP and DHCP you need to find which traffic full this Queue 
link below show you many solution you can reduce the traffic to this Queue.
https://www.cisco.com/c/en/us/support/docs/switches/catalyst-9300-series-switches/217429-troubleshoot-slow-or-intermittent-dhcp-o.html

[Richard Burts]

There are some things that we do not know about this environment that might be helpful. Am I correct in understanding that the clients getting DHCP addresses are connected to this 9300? What is providing the DHCP? Is it configured on the 9300? Or is there a separate DHCP server?

It is interesting that clients usually get an address but it is slow. Is it always slow? Or do clients sometimes get an address more quickly and sometimes very slowly? Are there any messages in syslog about issues that might impact DHCP? If DHCP is on another device are there any log messages on that device that might relate to the slowness? Are there any other signs of slowness in the network?

It might be helpful if you would post the config of the 9300.

[medharrak]

the 9300 is the core-Switch , the clients are connected on the Access-switches , but we did test with the clients directly connected to the Core-Switch and it's the same issue, it's very slow can take a minutes , sometimes more than 10min.

The DHCP server is configured on the Windows Server.

As I mentioned the same setup was working fine before with C3850, the issue appears when We change it by the 9300.

And i'm sure that it is related to the 9300 switch because recently we did migrate another site to 9300 and it's the same issue with the DHCP.

interface Vlan55
descriptionVLAN55
ip address 10.213.35.1 255.255.255.0
ip helper-address 10.213.33.111
end

[MHM Cisco World]

show my comment above it is Queue full issue. 
MHM 

[medharrak]

seems ICMP redirect and broadcast queue issue

[MHM Cisco World]

as I mention before, check link there are many solution you can use to reduce traffic in this queue.
MHM