mroute questions

[gongya001]

On R5, I can ping 239.1.1.1

R5(config)#do ping 239.1.1.1

Type escape sequence to abort.

Sending 1, 100-byte ICMP Echos to 239.1.1.1, timeout is 2 seconds:

Reply to request 0 from 1.1.1.1, 1 ms

But the mroute table does not have the route

R5#show ip mroute

IP Multicast Routing Table

Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,

       L - Local, P - Pruned, R - RP-bit set, F - Register flag,

       T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,

       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,

       U - URD, I - Received Source Specific Host Report,

       Z - Multicast Tunnel, z - MDT-data group sender,

       Y - Joined MDT-data group, y - Sending to MDT-data group,

       G - Received BGP C-Mroute, g - Sent BGP C-Mroute,

       N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,

       Q - Received BGP S-A Route, q - Sent BGP S-A Route,

       V - RD & Vector, v - Vector, p - PIM Joins on route,

       x - VxLAN group

Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join

 Timers: Uptime/Expires

 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.0.1.40), 00:06:06/00:02:40, RP 0.0.0.0, flags: DCL

  Incoming interface: Null, RPF nbr 0.0.0.0

  Outgoing interface list:

    Ethernet0/0, Forward/Dense, 00:06:06/stopped

On R4, I have

R4#show ip mroute

IP Multicast Routing Table

Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,

       L - Local, P - Pruned, R - RP-bit set, F - Register flag,

       T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,

       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,

       U - URD, I - Received Source Specific Host Report,

       Z - Multicast Tunnel, z - MDT-data group sender,

       Y - Joined MDT-data group, y - Sending to MDT-data group,

       G - Received BGP C-Mroute, g - Sent BGP C-Mroute,

       N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,

       Q - Received BGP S-A Route, q - Sent BGP S-A Route,

       V - RD & Vector, v - Vector, p - PIM Joins on route,

       x - VxLAN group

Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join

 Timers: Uptime/Expires

 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.1.1.1), 00:06:13/stopped, RP 0.0.0.0, flags: D

  Incoming interface: Null, RPF nbr 0.0.0.0

  Outgoing interface list:

    Ethernet0/2, Forward/Dense, 00:06:13/stopped

    Ethernet0/0, Forward/Dense, 00:06:13/stopped

    Ethernet0/1, Forward/Dense, 00:06:13/stopped

(172.31.1.5, 239.1.1.1), 00:00:59/00:02:00, flags: T

  Incoming interface: Ethernet0/2, RPF nbr 172.31.1.5

  Outgoing interface list:

    Ethernet0/1, Prune/Dense, 00:00:59/00:02:00

    Ethernet0/0, Forward/Dense, 00:00:59/stopped

(*, 224.0.1.40), 00:08:53/00:02:56, RP 0.0.0.0, flags: DCL

  Incoming interface: Null, RPF nbr 0.0.0.0

  Outgoing interface list:

    Ethernet0/2, Forward/Dense, 00:07:24/stopped

    Ethernet0/0, Forward/Dense, 00:08:53/stopped

    Ethernet0/1, Forward/Dense, 00:08:53/stopped

Anything  have I missed here ? 

thanks !!

[Jon Marshall · Accepted solution]

R5 is acting as the source for the multicast stream so it is not routing it, that only happens when the packets are received by R4. 

I think the confusion is due to the fact you are using a router as a source as a test but usually the source would be a server and you would not expect that to participate in multicast routing. 

Jon

[gongya001]

thanks ! 

When R5 ping 239.1.1.1, does it use routing table or it send ping as multicast ?  if R5 has multiple interfaces, how does it decide which interface it should use to send ping ?

[gongya001]

thanks so much !!