From: Edison Ortiz (edisonmortiz@gmail.com)
Date: Sun Mar 25 2007 - 16:49:06 ART
Without ip pim nbma-mode, R2 forwards mcast traffic out of all PVCs. It
doesn't know the serial interface is shared by multiple PVCs.
With ip nbma-mode, pim will acknowledge the PVCs independently.
You can see the differences on the 'show ip mroute' command with and without
ip nbma-mode. With ip nbma-mode, it shows each neighbors
ip address. Without ip nbma-mode, it just shows in the interface.
----- Original Message -----
From: "Bit Gossip" <bit.gossip@chello.nl>
To: "ccielab" <ccielab@groupstudy.com>
Sent: Sunday, March 25, 2007 11:37 AM
Subject: Re: multicast very fundamental
>I agree that the only explanation is that r2 somehow forwards multicast
> prune from r3 to r1
> But this is against all my understanding so far ....:-(
>
> Do you mind to expand on your explanation?
>
> Thanks,
> Luca.
>
> ----- Original Message -----
> From: "Edison Ortiz" <edisonmortiz@gmail.com>
> To: "Bit Gossip" <bit.gossip@chello.nl>; "ccielab"
> <ccielab@groupstudy.com>
> Sent: Sunday, March 25, 2007 4:12 PM
> Subject: Re: multicast very fundamental
>
>
>> You need to enable pim nbma mode in R2's serial interface to avoid the
>> flooding from spoke to spoke.
>>
>> ----- Original Message -----
>> From: "Bit Gossip" <bit.gossip@chello.nl>
>> To: "ccielab" <ccielab@groupstudy.com>
>> Sent: Sunday, March 25, 2007 6:54 AM
>> Subject: multicast very fundamental
>>
>>
>> > Group I am stuck for days on this very fundamental multicast
>> > mechanics...
>> > I noticed this strange thing while playing with the multicast task of
>> > IEWB4-LAB02 and couldn't get to the bottom of it; then I gave up.
>> > Now I have reproduced it in a very simple scenario, and the pb is still
>> > there.
>> >
>> > r1
>> > |
>> > |
>> > r2 ----<
>> > |
>> > |
>> > r3
>> >
>> > *) Frame relay hub'n'spoke with r2=hub, only serial physical interfaces
>> > *) Full reachability via OSPF
>> > *) PIM-SM with r2=RP; multicast source=132.1.26.8 attached to r2 f1/0
>> > for group 228.28.28.28; receivers attached to r1 and r3
>> > *) it works fine, all receivers get the group
>> >
>> > And now the funny part !!
>> > *) there is no layer 2 connectivity between r1 and r3 as you can see
>> > below; but still r1 HEARS the prune from r3 and OVERRIDES it !!!!!!!!
>> > How is it possible ??????
>> >
>> > When r3 leaves the group this is the pim debug on r1:
>> >
>> > PIM(0): Received v2 Join/Prune on Serial0/0 from 132.1.0.3, not to us
>> > PIM(0): Prune-list: (*, 228.28.28.28) RP 150.1.2.2
>> > PIM(0): Set join delay timer to 1000 msec for (150.1.2.2/32,
>> > 228.28.28.28) on Serial0/0
>> > PIM(0): Building Periodic (*,G) Join / (S,G,RP-bit) Prune message for
>> > 228.28.28.28
>> > PIM(0): Insert (*,228.28.28.28) join in nbr 132.1.0.2's queue
>> > PIM(0): Building Join/Prune packet for nbr 132.1.0.2
>> >
>> >
>> >
>> > This one is a classical example mentioned in Cisco doc, where PIM-SM
>> > goes into trouble because one spoke cannot hear the prune from another
>> > one and then override it; but in my lab it doesn't seem to happen....
>> >
>> > Below this line config and show's
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > r1
>> >
>> > ip multicast-routing
>> > interface Loopback0
>> > ip address 150.1.1.1 255.255.255.0
>> > ip pim sparse-dense-mode
>> > ip igmp join-group 228.28.28.28
>> > !
>> > interface FastEthernet0/0
>> > ip address 132.1.17.1 255.255.255.0
>> > ip pim sparse-mode
>> > speed 100
>> > full-duplex
>> > !
>> > interface Serial0/0
>> > ip address 132.1.0.1 255.255.255.0
>> > ip pim sparse-mode
>> > encapsulation frame-relay
>> > ip ospf network point-to-multipoint
>> > no fair-queue
>> > clock rate 64000
>> > frame-relay map ip 132.1.0.2 102 broadcast
>> > no frame-relay inverse-arp
>> > !
>> > router ospf 1
>> > router-id 150.1.1.1
>> > log-adjacency-changes
>> > passive-interface default
>> > no passive-interface Serial0/0
>> > network 132.1.0.1 0.0.0.0 area 0
>> > network 132.1.17.1 0.0.0.0 area 0
>> > network 150.1.1.1 0.0.0.0 area 0
>> > !
>> > ip pim rp-address 150.1.2.2
>> > ip pim spt-threshold infinity
>> >
>> > --------
>> >
>> > r1#show frame-relay map
>> > Serial0/0 (up): ip 132.1.0.2 dlci 102(0x66,0x1860), static,
>> > broadcast,
>> > CISCO, status defined, active
>> > r1#ping 224.0.0.2
>> >
>> > Type escape sequence to abort.
>> > Sending 1, 100-byte ICMP Echos to 224.0.0.2, timeout is 2 seconds:
>> >
>> > Reply to request 0 from 132.1.17.7, 4 ms
>> > Reply to request 0 from 132.1.0.2, 88 ms
>> > Reply to request 0 from 150.1.1.1, 4 ms
>> >
>> > r1#show ip mroute 228.28.28.28
>> > IP Multicast Routing Table
>> >
>> > (*, 228.28.28.28), 00:49:48/00:02:58, RP 150.1.2.2, flags: SCL
>> > Incoming interface: Serial0/0, RPF nbr 132.1.0.2
>> > Outgoing interface list:
>> > Loopback0, Forward/Sparse-Dense, 00:47:47/00:02:39
>> >
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >
>> > r2
>> >
>> > ip multicast-routing
>> > !
>> > interface Loopback0
>> > ip address 150.1.2.2 255.255.255.0
>> > ip pim sparse-mode
>> > !
>> > interface FastEthernet1/0
>> > ip address 132.1.26.2 255.255.255.0
>> > ip pim sparse-mode
>> > no ip mroute-cache
>> > duplex full
>> > !
>> > interface Serial4/0
>> > ip address 132.1.0.2 255.255.255.0
>> > ip pim sparse-mode
>> > encapsulation frame-relay
>> > ip ospf network point-to-multipoint
>> > no ip mroute-cache
>> > serial restart-delay 0
>> > frame-relay lmi-type cisco
>> > !
>> > router ospf 1
>> > router-id 150.1.2.2
>> > log-adjacency-changes
>> > passive-interface default
>> > no passive-interface Serial4/0
>> > network 132.1.0.2 0.0.0.0 area 0
>> > network 132.1.26.2 0.0.0.0 area 0
>> > network 150.1.2.2 0.0.0.0 area 0
>> > !
>> > ip pim rp-address 150.1.2.2
>> >
>> > --------
>> >
>> > r2#show frame-relay map
>> > Serial4/0 (up): ip 132.1.0.1 dlci 201(0xC9,0x3090), dynamic,
>> > broadcast,
>> > CISCO, status defined, active
>> > Serial4/0 (up): ip 132.1.0.3 dlci 203(0xCB,0x30B0), dynamic,
>> > broadcast,, status defined, active
>> > r2#ping 224.0.0.2
>> >
>> > Type escape sequence to abort.
>> > Sending 1, 100-byte ICMP Echos to 224.0.0.2, timeout is 2 seconds:
>> >
>> > Reply to request 0 from 150.1.2.2, 1 ms
>> > Reply to request 0 from 132.1.0.1, 76 ms
>> > Reply to request 0 from 132.1.0.3, 64 ms
>> >
>> > r2#show ip mroute 228.28.28.28
>> > IP Multicast Routing Table
>> >
>> >
>> > (*, 228.28.28.28), 01:01:35/00:03:10, RP 150.1.2.2, flags: S
>> > Incoming interface: Null, RPF nbr 0.0.0.0
>> > Outgoing interface list:
>> > Serial4/0, Forward/Sparse, 00:50:51/00:03:10
>> >
>> > (132.1.26.8, 228.28.28.28), 00:01:18/00:03:22, flags: T
>> > Incoming interface: FastEthernet1/0, RPF nbr 0.0.0.0
>> > Outgoing interface list:
>> > Serial4/0, Forward/Sparse, 00:01:18/00:03:10
>> >
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >
>> > r3
>> >
>> > ip multicast-routing
>> > !
>> > interface Loopback0
>> > ip address 150.1.3.3 255.255.255.0
>> > !
>> > interface FastEthernet3/0
>> > ip address 132.1.33.3 255.255.255.0
>> > ip pim sparse-mode
>> > ip policy route-map T8.2
>> > duplex full
>> > !
>> > interface Serial4/0
>> > bandwidth 512
>> > ip address 132.1.0.3 255.255.255.0
>> > ip pim sparse-mode
>> > encapsulation frame-relay
>> > ip ospf network point-to-multipoint
>> > serial restart-delay 0
>> > frame-relay map ip 132.1.0.2 302 broadcast
>> > no frame-relay inverse-arp
>> > !
>> > router ospf 1
>> > router-id 150.1.3.3
>> > log-adjacency-changes
>> > passive-interface default
>> > no passive-interface Serial4/0
>> > network 132.1.0.3 0.0.0.0 area 0
>> > network 132.1.3.3 0.0.0.0 area 0
>> > network 132.1.33.3 0.0.0.0 area 0
>> > network 150.1.3.3 0.0.0.0 area 0
>> > !
>> > ip pim rp-address 150.1.2.2
>> > ip pim spt-threshold infinity
>> >
>> > -----------
>> >
>> > r3#show frame-relay map
>> > Serial4/0 (up): ip 132.1.0.2 dlci 302(0x12E,0x48E0), static,
>> > broadcast,
>> > CISCO, status defined, active
>> > r3#ping 224.0.0.2
>> >
>> > Type escape sequence to abort.
>> > Sending 1, 100-byte ICMP Echos to 224.0.0.2, timeout is 2 seconds:
>> >
>> > Reply to request 0 from 132.1.0.2, 116 ms
>> >
>> > r3#show ip mroute 228.28.28.28
>> > IP Multicast Routing Table
>> >
>> > (*, 228.28.28.28), 00:02:13/00:02:59, RP 150.1.2.2, flags: SCL
>> > Incoming interface: Serial4/0, RPF nbr 132.1.0.2
>> > Outgoing interface list:
>> > FastEthernet3/0, Forward/Sparse, 00:02:13/00:02:33
>> >
>> > _______________________________________________________________________
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>
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