Auto-rp in sparse-dense mode

[AnandJalawadi]

Hi,

Could anybody would put light on the fact that Juniper chooses Sparse-dense mode for auto-rp to work in mulicasting

thanks

Anand

[Harold Ritter]

Sparse-dense mode is generally required for auto-rp to work. The dense mode is only required for the auto-rp announce and discovery process.

With IOS, there is a command that allow auto-rp to be ran in sparse-mode only. It is called autorp listener. For more information on that command, please refer to the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fiprmc_r/mult/1rfmult2.htm#wp1090395

Hope this helps,

[AnandJalawadi]

Herold,

thanx for reply,however all our Cisco edge and core router are working in sparse mode without auto-rp listener. and still auto-rp is working

regards

Anand

[Harold Ritter]

Anand,

If autorp listener is not enabled only routers adjacent to the RP will receive the announce and discovery messages. These messages will not be relayed to the non-directly connected routers.

If all routers are not directly adjacent to the RP then you need to use autorp listener or to enable pim sparse-dense on all interfaces.

Hope this helps

[AnandJalawadi]

Herold,

thanx again,I completely agree with your explaination,but my routers are learning rp through auto-rp without auto-rp listener command .plz See the following output(IP address has been changed for security reasons) and RP is certainly not adjacent to this edge router and all interfaces are enabled in sparse mode.

cbt-rtr-pe-01#sh ip pim rp

Group: 225.0.0.1, RP: 192.168.1.1, v2, uptime 01:58:31, expires 00:02:54

cbt-rtr-pe-01#sh ip pim rp mapping

PIM Group-to-RP Mappings

Group(s) 224.0.0.0/4

RP 192.168.1.1 (?), v2v1

Info source: x.x.x.188 (?), elected via Auto-RP

Uptime: 01:54:55, expires: 00:02:44

regards

Anand

[Harold Ritter]

Anand,

I don't know enough about your network to comment but what I know for a fact is that you either need to be adjacent to the RP, have autorp listener enabled or have interfaces configured as sparse-dense for the RP discovery to work properly.

Hope this helps,

[markausten]

The AUTO-RP groups may be operating in sparse-mode resulting in shared trees for these groups. It may work in some cases but in a large network it would be nonderministic. You need to run sparse-dense or autorp-listener, I believe there may be some changes in recent IOS versions so Auto-RP can operate with the interface set as sparse only but Auto-RP will still operate in dense mode.