12-20-2010 04:44 AM - edited 03-06-2019 02:37 PM
Hi all, I'm reading about proprietary uplinkfast function and it's saying that when switch will switch to blocked port, it will send some "dummy" multicast packets to "advertise" that mac addresses are now reachable on this previously-blocked-port. I checked this function in lab, but I didn't noticed any multicast packets. After I unplug the cable it's very quick - 1 ping is lost, not more. But how does it know where to send pings after blocked port is unblocked? Without that multicast packet, I assume it's broadcasted on all active ports and 1 will reply... Correct?
12-21-2010 12:17 PM
Hello Ziga,
In your lab, are you looking for dummy packets to 01-00-0c-cd-cd-cd ?
12-21-2010 12:41 PM
Hello,
Yes, that's the one ... I was trying a little more and noticed that when I unplug the "working cable" (and second switch quickly switch to prevoiusly-blocked-port), first ping will be broadcasted on all ports on the first switch, because it doesn't know where the mac address is. So it's anohter proof that second switch never sent any "dummy multicast" packet. I'm using 3550 swithes, maybe the IOS or hardware is a problem
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide