Saturday, January 17, 2009

IE Vol1 PIM Sparse Mode Complete

My rustiness with multicast is evident in the amount of time it's taking me to troubleshoot silly issues. The fundamental difference in configuring sparse mode vs. dense mode is that an RP is required. When given the option, don't bother messing with dynamic protocols and just assign a static RP.

No problem there. I throw the static RP on each router, verify pim neighbors, see the 224.0.1.40 flow--everything seems to be working great. One problem, the flow from R7 didn't appear anywhere. Debugs don't seem to be telling me anything special.

And then it dawns on me. Do the routers actually have a route to the RP? No! I used R2's loopback, but never actually assigned the loopback into OSPF. I fix that and bam! everything comes up as expected.

Bottom line, I still don't have any sort of troubleshooting methodology for multicast. Most likely because I simply haven't spent enough time troubleshooting multicast issues. Hopefully by time I get through the rest of the volume I exercises I'll be more comfortable.

1 comment:

Andrey Tsadikov said...

HI, its looks like we have a sane situation :)

I like your posts, its very usefull to summarize the subjects.

Good luck.