OK, here's my situation.

This is on the internet. The 6224 is the router in this picture and physically resides in Kanata.

Both VLAN 1697 and 3994 are provided by an internet service provider. These VLANs are provided through a single 1Gb ethernet wire.

The Kanata hosts are directly attached to the 6224; the other two sites are remote.

VLAN 3994 is a single IP address space, so theoretically it shouldn't matter physically where the hosts on that subnet are.

Here's the problem.

I have a monitoring system which is connected further into the internet, so probes from the monitor would come in to this diagram on the 1697 VLAN.

When I ping hosts at Albert or Bells Corners from the internet, there is 0 loss. The connection looks perfect.

When I ping hosts at Kanata, I lose anywhere from 10 to 40% of the pings. The loss is not predictable, but: when I do lose them, I always lose at least 3, usually 4, rarely more, pings in a bunch.

I have attached a monitor directly to the 6224 in Kanata on 3994..

When the monitor pings the 6224 routing interface, I see exactly the same loss pattern -- but NOT at the same time as the loss from the remote system. Ping time is around 1ms.

When the monitor pings another system directly attached to the 6224, there is 0 loss. Ping time is about 0.1ms, one-tenth of the time to ping the router.

Anyone know what is going on here?