Why is there 5-10ms latency to the LAN port of the Cisco DPC3939b?

I might just have to get the Netgear back, this jitter is absurd. 😕

Hello pflog and welcome,

Could you share with us where you are actually performing these ping from?  Those ping timing values you posted are not shabby at all.  You must make sure that on your DPC that the WAN and LAN DNSs are programmed within their respective segements. If you can log into the DPC and have to WAN segment, then make sure the DNSs are programmed in. If you can't find it then call 800-391-3000, use technical high spped internet, and have a technical agent log in to set these up for you.

Could you also post your upstream and downstream DPC parameters and share with us what your business networking functionality is that these posted ping values would be negatively impacting.

Thanx and look forward to hearing from you.

This is running from a FreeBSD 10.1 box (the firewall/router/NAT device) attached directly to LAN port #1 of the Cisco device.

There is absolutely no reason why there should be 1ms latency, let alone spikes above 10ms to a device connected directly by cat 5e.

As a comparison, here's the ping from the same box on its LAN segment THROUGH a switch to another device:

PING 10.0.0.4 (10.0.0.4): 56 data bytes
64 bytes from 10.0.0.4: icmp_seq=0 ttl=64 time=0.213 ms
64 bytes from 10.0.0.4: icmp_seq=1 ttl=64 time=0.224 ms
64 bytes from 10.0.0.4: icmp_seq=2 ttl=64 time=0.200 ms
64 bytes from 10.0.0.4: icmp_seq=3 ttl=64 time=0.209 ms
64 bytes from 10.0.0.4: icmp_seq=4 ttl=64 time=0.205 ms

--- 10.0.0.4 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.200/0.210/0.224/0.008 ms

~100-200 micro seconds (.2 ms) is about what I would expect. Not 1ms and certainly not 10ms+.

Thanks!

I haven't used the Cisco box so I don't know if it has this capability, but have you tried setting both devices to manual duplex/speed selection? Usually this only works if both have manual, you don't want to set one to manual and the other to auto. But if you can, try setting both to manual 1000mbps/full duplex. I run pfsense which runs on FreeBSD and have an SMC Comcast gateway and both are capable of manual speed/duplex.

Unfortunately I don't see a place to set the duplex/speed settings.

FWIW, the Cisco reports the LAN port as "1 Gbps" and the FreeBSD box indicates auto-negotiation @ 1000baseT-FD:

media: Ethernet autoselect (1000baseT )

So I think the auto-negotiation is working properly.

Also I've spoken to a couple of other people with Ciscos and they see the same high latency to the LAN side of the Cisco.

*bump* Any ideas here?

Can others with a Cisco confirm the high latency to 10.1.10.1 (the LAN facing interface's IP)?