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New Member

Understand output from "show ip mroute" - Help

Hi,

This is quite basic, can some one please explain what the output below shows. Why do I see NULL in outgoing and incoming? Is there a problem here?

sh ip mroute 239.48.181.10
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,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report, Z - Multicast Tunnel
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.48.181.10), 3w3d/stopped, RP 10.239.45.1, flags: SP
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list: Null

(10.44.80.31, 239.48.181.10), 00:00:07/00:02:52, flags: P
  Incoming interface: GigabitEthernet1/4, RPF nbr 10.10.51.145, Partial-SC
  Outgoing interface list: Null

(10.45.180.38, 239.48.181.10), 1w0d/00:02:59, flags: PT
  Incoming interface: Vlan180, RPF nbr 0.0.0.0, RPF-MFD
  Outgoing interface list: Null

show ip mroute count:

Group: 239.48.181.10, Source count: 4, Packets forwarded: 0, Packets received: 31325457
  RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0
  Source: 10.44.80.31/32, Forwarding: 0/0/0/0, Other: 18/18/0
  Source: 10.45.180.38/32, Forwarding: 0/-229/0/281, Other: 31325425/0/31325425

Thanks in advance

Dan

Everyone's tags (3)
6 REPLIES
New Member

Re: Understand output from "show ip mroute" - Help

dan_track wrote:

Hi,

This is quite basic, can some one please explain what the output below shows. Why do I see NULL in outgoing and incoming? Is there a problem here?

sh ip mroute 239.48.181.10
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,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report, Z - Multicast Tunnel
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.48.181.10), 3w3d/stopped, RP 10.239.45.1, flags: SP
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list: Null

(10.44.80.31, 239.48.181.10), 00:00:07/00:02:52, flags: P
  Incoming interface: GigabitEthernet1/4, RPF nbr 10.10.51.145, Partial-SC
  Outgoing interface list: Null

(10.45.180.38, 239.48.181.10), 1w0d/00:02:59, flags: PT
  Incoming interface: Vlan180, RPF nbr 0.0.0.0, RPF-MFD
  Outgoing interface list: Null

show ip mroute count:

Group: 239.48.181.10, Source count: 4, Packets forwarded: 0, Packets received: 31325457
  RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0
  Source: 10.44.80.31/32, Forwarding: 0/0/0/0, Other: 18/18/0
  Source: 10.45.180.38/32, Forwarding: 0/-229/0/281, Other: 31325425/0/31325425

Thanks in advance

Dan

Hi Dan,

Is this output taken from the RP itself. If so than that is probably the reason why the Incoming interface is null on the *,G entry. The reason the S,G entry might be null is probably because you do not have any receivers that are requesting the traffic.

Disclaimer: I am definetly no multicast expert hence I apologize if this might be incorrect and would appreciate if some of the experts on the forum could confirm this as well.

Thx

New Member

Re: Understand output from "show ip mroute" - Help

Thanks,

This was done on the RP itself. Can someone please clarify this.

Thanks

Dan

Hall of Fame Super Silver

Re: Understand output from "show ip mroute" - Help

Hello Dan,

until the code P is part of the state of the mroute it is correct to see outgoing interface = null.

>>sh ip mroute 239.48.181.10
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,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report, Z - Multicast Tunnel
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.48.181.10), 3w3d/stopped, RP 10.239.45.1, flags: SP
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list: Null

(10.44.80.31, 239.48.181.10), 00:00:07/00:02:52, flags: P
  Incoming interface: GigabitEthernet1/4, RPF nbr 10.10.51.145, Partial-SC
  Outgoing interface list: Null

(10.45.180.38, 239.48.181.10), 1w0d/00:02:59, flags: PT
  Incoming interface: Vlan180, RPF nbr 0.0.0.0, RPF-MFD
  Outgoing interface list: Null

>> end of show

according to the point of view of this device no one in other IP subnets has showed interest in receiving traffic for group 239.48.181.10.

However, there are two sources in two different subnets sending traffic using this group address.

Traffic is dropped that means it is not routed to other IP subnets.

if a PC joins the group the node should start to route for the group

Hope to help

Giuseppe

New Member

Understand output from "show ip mroute" - Help

Hi Giuseppe,

It would be great if you can advise what the word "stopped" in the first entry mean & why the RPF neighbor is 0.0.0.0 in the last entry?

Thanks a lot

Pradeep H A

New Member

Understand output from "show ip mroute" - Help

Hi,

i have the same issue is there any solution for the this?

HAL-HPSDC01-B01-CSW01#sh ip mroute 239.1.1.1

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

       V - RD & Vector, v - Vector

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

Timers: Uptime/Expires

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

(*, 239.1.1.1), 02:21:00/stopped, RP 10.10.10.1, flags: SP

  Incoming interface: Null, RPF nbr 0.0.0.0

  Outgoing interface list: Null

(10.23.1.250, 239.1.1.1), 02:21:00/00:02:06, flags: PT

  Incoming interface: Vlan301, RPF nbr 0.0.0.0

  Outgoing interface list: Null

thanks

New Member

Re: Understand output from "show ip mroute" - Help

It's NULL because route through RP was pruned due to SPT switchover from shared stree. That happens after first few packets then source starts sending packets to receivers via their own SPT, that makes the SPT via RP unnecessary then it is pruned (marked as P)

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