Multicast Lab Auto-RP

[ftermine83]

Hi ALL,

I have setup a lab in CML for testing multicast using Auto-RP but I cant see traffic flowing from the source to the receivers . I can see the (S,G) entry in the first hop router and the (*,G) entry in the RP .

Appreciate any feedback 

Thanks,

Francesco

[MHM Cisco World]

Do below changes 

1- R2 and R4

Ip pim send-rp- discover <using it loopack as source and ttl as 10>

2-R3 

Ip pim send-rp- announce 

3- all routers config it interface with 

Ip pim spare-dense-mode 

After that check multicast from source to receiver.

Thanks for waiting 

MHM

[ftermine83]

@MHM Cisco World : I have tried that and it didn't work . I have configured "ip pim auto-rp listener" which is the same as pim sparse-dense-mode under the interface configuration

I did a packet capture on R1 and I cant see the Register message leaving the router and then I found this article.  After  replacing  R1 with a NX-OS it started working as expected . Maybe it is an issue with CML  with ios-v nodes

 https://learningnetwork.cisco.com/s/question/0D56e0000CiJDGLCQ4/issues-with-multicast-in-cmlp-with-iosv?t=1713521909409

[MHM Cisco World]

ip pim auto-rp listener is not same as ad using

Ip pim spare-dense mode

Use exactly what I mentioned above, if it work then i will explain to you why you need it.

Use Routet not nexus 

MHM

[ftermine83]

@MHM Cisco World : I tried but you suggested in the previous post and it didnt work 

[MHM Cisco World]

Share the config of R3 R1 R2 after changing 

MHM

[ftermine83]

here are the config 

[ftermine83]

@MHM Cisco World : latest config here

[MHM Cisco World]

In R3

Ip pim send-rp- announce loopback <- this missing 

In R1 and R2

Ip pim autorp listening <- this missing 

MHM

[ftermine83]

@MHM Cisco World : in R3 I have already this config

R3# show running-config | i rp
ip pim send-rp-announce Loopback0 scope 10 interval 10

For R1 and R2 you mean to add ip pim autorp listener ? I did and still it doesnt work . anyway I already have dense-sparse mode configured in all interfaces

[Ramblin Tech]

Somewhat off topic: why use an RP at all? Why not use PIM-SSM instead? Do you need to support/model a legacy PIM-SM network or application?

[ftermine83]

yes I need to work on sparse mode network 

[hunnufisher]

How a multicast source comes to existence ? An IP host starts sending IP frames out with the multicast IP destination address. That's it... The story with rp election, sparse/dense mode, IGMP and so on - is not about multicast source at all - but about subsequest forwarding/routing of these multicast frames sent by said source. Multicast is connectionless UDP traffic.

[ftermine83]

@hunnufisher : exactly as you said , the source will start transmitting to a mcast group and then it is up to the network to deliver the stream . there is no signalling between source and first hop router

[MHM Cisco World]

If you see 

Show ip mroute 

There are three groups

One your multicast group

Other are .39 and .40

These last two groups is for announce and discovery of RP since you use auto-RP.

The R1 is not direct connect to R3 (auto-RP) this make R1 missing know the RP and hence the R1 can not forward multicast.

If you can do direct connect between R1 and R3 and check the multicast.

MHM

[ftermine83]

@MHM Cisco World : I have tried the option to connect R1 to R3 directly and it also didnt work. 

R1  is learning about the  RP from R2 which is configured as MA  

R1#show ip pim rp mapping
PIM Group-to-RP Mappings

Group(s) 224.0.0.0/4
RP 3.3.3.3 (?), v2v1
Info source: 2.2.2.2 (?), elected via Auto-RP
Uptime: 2d23h, expires: 00:00:29