Multicast Question

ITtech2010

Hi all,

I have a question on Multicast. My environment is using Dense mode to receive multicast traffic. We have for example a A-Feed (binary data) source coming from Carlstadt and a B-Feed (ascii data) coming from Philly. I think eventually my company wants to go into Sparse Mode.

I know with Dense mode the traffic floods to all of our customers that want to receive the data. My question is how would this work with Sparse Mode?

Would I have to configure a router (or 2) as a RP and configure it to allow the A+B feed to distribute the data to our customers?

I guess the part I am stuck at is how would I configure a router to receive data from both A+B feed customers to distribute the data.

Thanks for your help.

SubnetZero

In Sparse mode there are 3 methods of specifying the RP

- Static Assignment
- Auto-RP (Cisco Proprietary)
- Bootstrap Router (BSR - IETF standard)

Configuration for these methods are as follows (with static being the easiest if there aren't many PIM enabled routers)

Static RP - Choose your RP and configure it on all of your multicast enabled routers

ip pim rp-address 12.12.12.12 (acl)

Auto-RP - Auto-RP is a very old protocol originally designed for dense-mode operations!! If you want to run auto-rp you need to run in ether dense-mode or sparse-dense-mode. There actually is a way to get it to work in sparse mode however this protocol was designed for dense mode!

Note: Although I don't recommend it you can use it in PIM-SM networks but enabling the "ip pim autorp listener" command on all of your PIM enabled routers

On the router to be the RP

ip pim send-rp-announce (src-intf) scope (ttl) group-list (acl)

On the router to be the Mapping Agent (MA)

ip pim send-rp-discovery scope (ttl)

the MA is needed somewhere on the network and can be on the same router as your RP commands, doesn't matter.

BSR - IETF (open standard) which is their way of dynamically learning RP information

RP candidates are configured

ip pim rp-candidate (intf) (ttl)(pri) [group-list]

The PRI is for priority. Highest priority wins. If tied highest IP address

BSR config

ip pim bsr-candidate (intf) (hash) (pri)

Don't forget to go around to all your PIM enabled interfaces and switch them from dense-mode to sparse-mode (or sparse-dense-mode) and test it this in a lab environment before rolling it out into production!

SubnetZero

I would also highly recommend you consult the IP Multicast configuration guide from Cisco

This documentation has been moved - Configuring Basic IP Multicast  [Support] - Cisco Systems

I also highly recommend you consider reading the Routing TCP/IP Volume 2 (Doyle)

http://www.amazon.com/Routing-TCP-CCIE-Professional-Development/dp/1578700892

This book is a great reference for IP Multicast!

Cheers!

ITtech2010

Thanks for your input Subzero! I appreciate you taking the time to explain it. I have the multicast book from Beau Williamson from 1999. People say it's still a great reference so i'll look into that and the tcp ip book you recommended.:)

Now that I have an understanding of how sparse mode will work i'll on a lab to see how it would come across. My co-workers are purchasing a powerful server so we can run gns3 on it. This will be perfect to implement in the lab.