Cable Forum - View Single Post - 50M Think Broadband Ping Monitor Results (POST YOURS)

qasdfdsaq · 23-03-2012, 18:36

It's quite possible that modem mode would have slightly lower latency, but I wouldn't expect that much simply between the two modes. There's a lot of variables though, for example the Superhub's firmware may simply not be programmed to respond to pings at the highest priority, something that is quite common on carrier network equipment. Another example variable would be the SH needing to inspect the IP packet in router mode, determine if it is for itself or a device being NAT'ed behind it and then determine where to pass it to, a process that takes time, and something it doesn't have to do in "modem mode". Also, higher average CPU load in router mode, etc.

In the end I'd expect ~0.5-1ms difference between the two modes but larger differences are probably a result of different routing in other parts of the network.

If we wanted to make a direct comparison between the SH in modem and router mode, best thing would be to ping from something *behind* the SH rather than relying on the SH itself to respond to pings - i.e. use the same endpoints in both situations, and also to try obtain the SH's WAN MAC and clone that if so that the PC/router would get the same IP address from VM's network. That'd rule out any differences in routing based on IP address.

23-03-2012, 18:36	#1159
qasdfdsaq cf.mega poster Join Date: Aug 2004 Posts: 11,207	Re: Think Broadband Ping Monitor Results (POST YOURS) It's quite possible that modem mode would have slightly lower latency, but I wouldn't expect that much simply between the two modes. There's a lot of variables though, for example the Superhub's firmware may simply not be programmed to respond to pings at the highest priority, something that is quite common on carrier network equipment. Another example variable would be the SH needing to inspect the IP packet in router mode, determine if it is for itself or a device being NAT'ed behind it and then determine where to pass it to, a process that takes time, and something it doesn't have to do in "modem mode". Also, higher average CPU load in router mode, etc. In the end I'd expect ~0.5-1ms difference between the two modes but larger differences are probably a result of different routing in other parts of the network. If we wanted to make a direct comparison between the SH in modem and router mode, best thing would be to ping from something behind the SH rather than relying on the SH itself to respond to pings - i.e. use the same endpoints in both situations, and also to try obtain the SH's WAN MAC and clone that if so that the PC/router would get the same IP address from VM's network. That'd rule out any differences in routing based on IP address.