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Help with L3 DHCP Routing on M4300 series
Hey guys,
I am currently trying to set up L3 DHCP routing on our Netgear M4300-series switches and I am struggeling a bit. Main problem: our core switches M4300-12x12f (as can bee seen on my attach...
- On an asymmetrical link, where the upload rate is a fraction of the download rate it’s possible to choke the network with upload data. So for example with a large TCP download where packets are acknowledged by the receiving computer then there can be a corresponding high upload of data, and if the upload rate limit is significantly lower that the download rate limit then the Internet connection can grind to a halt. The first few paragraphs of this .pdf might explain better than I can; http://www.sigcomm.org/sites/default/files/ccr/papers/2012/January/2096149-2096158.pdf
Hi Agsy,
Welcome to NETGEAR community!
M4300 support the function "UDP Relay" could resolve your concern that relay DHCP service cross different VLAN.
Please check following screenshot and user manual to deploy it.
May the solution help you:smileyhappy:
Thanks,
Daniel.
Cheers Daniel,
thanks a lot for your detailed instructions.
I tried to setup our Core switches as described by you, however, without great success... Here's what I did so far:
- Assigned VLAN 20 to a port for testing (Access mode)
- setup VLAN routing for VLANs 20 (client network) and 100 (Server network, where DHCP server is located)
- Configured UDP relay for VLAN 20 (tried both 192.168.100.3 (DHCP server address) and 192.168.100.254 (routing interface of router) as destination address:
What I can see is the hit counter increasing for UDP packets in VLAN 20, as soon as I connect a device in DHCP mode. However, when I mirror that VLAN 20 port and check with Wireshark, I still see the DHCP Discover packets bradcasting to 255.255.255.255.
In case it might help troubleshooting, here is the current routing table of our core switches:
What am I missing?
Thanks again for your help!
Cheers
SaschaDanielZhang wrote:
Hi Agsy,
Welcome to NETGEAR community!M4300 support the function "UDP Relay" could resolve your concern that relay DHCP service cross different VLAN.
Please check following screenshot and user manual to deploy it.May the solution help you:smileyhappy:
Thanks,
Daniel.
Hi Agsy,
Could you please check the Server IP is available(pingable) on network?
M4300 will try to get ARP(IP/MAC) for server IP before relay packets.(Usually use a ping for it)
Because M4300 need to know the actual IP address and MAC address of server
So if your server IP is behind firewall or not pingable.
We need to add static ARP for it that M4300 will forward correctly with DHCP L3 relay.
Let me know if you have further concern.:smileyhappy:
Thanks,
Daniel.
Hi Daniel,
sorry for my late response to your last suggestion. We finally got everything up and running, thanks to your valuable input.
In the end it was just a missing modification to the Windows routing table on our Windows-DHCP server. UDP relaying was working all the time, but the return packets were just mis-routed ;)
I marked your first reply as a solution for my problem.
Cheers
Sascha
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