Can dhcp across wan cause excessive broadcasts and latency issues (voip)

[hmc2500]

e had configured a site to obtain dhcp address from the hub site about 2 months ago. 

we have had no reported issues the weeks immediately thereafter. However about a month later we have been experiencing voice latency issues. I'm just wondering can having dhcp across the WAN cause broadcast or latency issues? how can you troubleshoot this? 

WE have ip helper-address configured on the WAN facing interface on the L3 switch in the remote site.

We have this configured for about six /24 subnets.

[Richard Burts]

We do not have much detail to work with here and that impacts our ability to give good advice. As a general statement the more traffic you send over the WAN the more opportunity there is for it to impact performance. If something were happening at the remote site that generated  LOT of requests for DHCP it could potentially impact performance. 

Do you have any management tools that monitor your WAN link? Do they show increase in traffic level? Do you get any management reports from the provider about the WAN link? Do those reports show any potential issues?

I am a bit puzzled at your statement that you have helper addresses on the WAN facing interfaces. The helper address should be applied to the interfaces where the clients are connected. I would not expect much client connection on the WAN interface.

[LanDownUnda]

The IP-Helper commands I expect to only work when used within a SVI or sub interface where you have clients connected to. the WAN Interface wouldn't be engaged to handle DHCP requests? the WAN Interface is the merely the exit point for DHCP queries and the entry point for DHCP answers.

I run a WAN that cators for about ..35-40 sites which all talk to a centralized DHCP server and haven't had any WAN performance issues. 

HTH

[hmc2500]

Yes, we have it set on the SVI's toward the WAN. It works however I'm not really sure if the broadcasts are excessive or are causing an issue. 

How can you monitor or verify this on a switch? and what are the ranges you would consider excessive?

We have solarwinds tools and altouhgh it's quick and useful I'm not sure if I can always rely on it. 

[Joseph W. Doherty]

It's a bit unlikely that DHCP across a WAN is causing your VoIP latency issues, but not, at Rick notes, impossible. If you don't have QoS configured to insure VoIP gets first priority to bandwidth, any transient data burst can disrupt VoIP. I.e. doesn't matter as much what the other traffic is, just that VoIP isn't "protected" or guaranteed the service level performance it requires.

Further, on "purchased" WAN (under-the-covers "shared") circuits, it's also possible that there's either transient congestion within the provider's infrastructure or perhaps the provider recently made a configuration error. (Provider issues can be harder to ascertain than a problem on your side and almost always a provider won't find their own error until you "rub their nose in it". [To be fair to providers, probably 99 times out of a 100, it's your network that's the problem, not theirs.])