PIM Dense Mode & 224.0.1.40

v.vasilev · ‎06-11-2009

Hello!

I have a pure dense mode network without any active senders/receivers.

Despite

this I have the following in the mroute table (on all routers).

(*, 224.0.1.40), 01:55:45/00:02:27, RP 0.0.0.0, flags: DCL

B Incoming interface: Null, RPF nbr 0.0.0.0

B Outgoing interface list:

B B B Ethernet0/0, Forward/Dense, 01:55:15/00:00:00

B B B Ethernet0/1, Forward/Dense, 01:55:40/00:00:00

B B B Serial0/0.1, Forward/Dense, 01:55:45/00:00:00

Is this normal?

Thank you!

Regards,

V.Vasilev

Harold Ritter · ‎06-12-2009

Hi Vladislav,

This is indeed normal behavior. All cisco routers subscribe to the multicast group address 224.0.1.40 automatically when configured for multicast. This group address is used to get RP information from the mapping agent(s).

Regards

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

shivlu jain · ‎06-15-2009

Hi Vasilev

224.0.1.40 and 39 is being used by auto-rp. This only comes when you configure ip pim sparse-dense mode.

regards

shivlu jain

Harold Ritter · ‎06-15-2009

Shivlu,

In fact, you will have the 224.0.1.40 entry in the multicast routing table regardless whether sparse-mode, dense-mode or sparse-dense-mode is configured.

Regards

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Hemant Kumar · ‎12-24-2012

Yes..This is a normal behaviour.This is because of autoRP which is on by default