Hi, Actually with this setup i dont think there will be a problem no matter how many pings are initiated.
As Ben pointed out the register message is unicasted to the RP. The RP (which itself is a receiver) then "pulls the source" toward itself with a SPT. Building the SPT is simply a matter of sending Joins toward R5 in this case. So R9 has no need for a RP (in this case) since everything is based off either A) Unicast Register Message or B) SPT initiated from R6. Kim On Mon, Apr 23, 2012 at 5:44 AM, Ben Hughes <[email protected]> wrote: > > Hi James, > > The register message is unicast so it it routed direct to R6 address > 215.0.0.6. Where this will break is when the routers try to switch over to > the shortest path tree. Try doing a ping with a repeat of 5. You'll > probably find that only the first ping gets a reply and the rest timeout. > > cheers, > Ben. > > > > From: James Roc <[email protected]<mailto:[email protected]>> > Date: Monday, 23 April 2012 12:32 PM > To: "[email protected]<mailto:[email protected]>" > <[email protected]<mailto:[email protected]>> > Subject: [OSL | CCIE_RS] PIM sparse-mode tree built through router with no RP > configuration > > Hi Everyone, > > Im playing around with multicast and found an interesting issue where I > have the following setup: > > r6 -- r1 --- r9 --- r5 > > I'm running pim sparse mode on all interfaces and ospf for unicast > connectivity. > > I have R6 setup as the RP with a static command on R6, R1 and R5 'ip pim > rp-address 215.0.0.6'. > > R9 has *no* RP configuration. > > I join a group on R6s loopback and ping from R5. The ping is successful. > > This is confusing to me as the way I understand PIM, R5 would send a group > 'Register' to the RP via R9. R9 would receive this but having no knowledge > of the RP, would simply drop the packet and respond back with a Register > Stop. > > However, somehow the group register is making its way to the RP, SPT is > built and pings flow. > > How/why is R9 forwarding the PIM register message if it does not know where > the RP is? > > Thanks > James > > > PIM Debugs below show the tree being built. > > r5 > ---- > > R5(config)#do ping 232.8.8.8 > > Type escape sequence to abort. > Sending 1, 100-byte ICMP Echos to 232.8.8.8, timeout is 2 seconds: > > *Mar 1 01:20:28.727: PIM(0): Check RP 215.0.0.6 into the (*, 232.8.8.8) > entry > *Mar 1 01:20:28.727: PIM(0): Send v2 Register to 215.0.0.6 for 215.0.0.5, > group 232.8.8.8 > *Mar 1 01:20:28.727: IP(0): s=215.0.0.5 (Loopback0) d=232.8.8.8 id=187, > ttl=254, prot=1, len=100(100), mroute olist null > *Mar 1 01:20:28.751: PIM(0): Received v2 Join/Prune on FastEthernet0/1.59 > from 215.5.9.9, to us > *Mar 1 01:20:28.751: PIM(0): Join-list: (215.0.0.5/32, 232.8.8.8), S-bit > set > *Mar 1 01:20:28.755: PIM(0): Add FastEthernet0/1.59/215.5.9.9 to > (215.0.0.5, 232.8.8.8), Forward state, by PIM SG Join. > R5(config)#do un all > All possible debugging has been turned off > R5(config)#do ping 232.8.8.8 > > Type escape sequence to abort. > Sending 1, 100-byte ICMP Echos to 232.8.8.8, timeout is 2 seconds: > > Reply to request 0 from 215.1.6.6, 28 ms > R5(config)# > > r9 > --- > > R9(config-subif)# > *Mar 1 01:20:26.907: PIM(0): Received v2 Join/Prune on FastEthernet0/1.19 > from 215.1.9.1, to us > *Mar 1 01:20:26.907: PIM(0): Join-list: (215.0.0.5/32, 232.8.8.8), S-bit > set > *Mar 1 01:20:26.907: PIM(0): Add FastEthernet0/1.19/215.1.9.1 to > (215.0.0.5, 232.8.8.8), Forward state, by PIM SG Join > *Mar 1 01:20:26.907: PIM(0): Insert (215.0.0.5,232.8.8.8) join in nbr > 215.5.9.5's queue > *Mar 1 01:20:26.907: PIM(0): Building Join/Prune packet for nbr 215.5.9.5 > *Mar 1 01:20:26.907: PIM(0): Adding v2 (215.0.0.5/32, 232.8.8.8), S-bit > Join > *Mar 1 01:20:26.907: PIM(0): Send v2 join/prune to 215.5.9.5 > (FastEthernet0/1.59) > R9(config-subif)# > > R9(config-subif)#do sh ip mroute > > (*, 232.8.8.8), 00:01:40/stopped, RP 0.0.0.0, flags: SP > Incoming interface: Null, RPF nbr 0.0.0.0 > Outgoing interface list: Null > > (215.0.0.5, 232.8.8.8), 00:01:40/00:02:33, flags: T > Incoming interface: FastEthernet0/1.59, RPF nbr 215.5.9.5 > Outgoing interface list: > FastEthernet0/1.19, Forward/Sparse, 00:01:40/00:02:48 > > R9(config-subif)# > > r1 > --- > > R1(config)# > *Mar 1 01:20:27.907: PIM(0): Received v2 Join/Prune on FastEthernet0/0.16 > from 215.1.6.6, to us > *Mar 1 01:20:27.907: PIM(0): Join-list: (215.0.0.5/32, 232.8.8.8), S-bit > set > *Mar 1 01:20:27.907: PIM(0): Check RP 215.0.0.6 into the (*, 232.8.8.8) > entry > *Mar 1 01:20:27.907: PIM(0): Add FastEthernet0/0.16/215.1.6.6 to > (215.0.0.5, 232.8.8.8), Forward state, by PIM SG Join > *Mar 1 01:20:27.907: PIM(0): Insert (215.0.0.5,232.8.8.8) join in nbr > 215.1.9.9's queue > *Mar 1 01:20:27.907: PIM(0): Building Join/Prune packet for nbr 215.1.9.9 > *Mar 1 01:20:27.907: PIM(0): Adding v2 (215.0.0.5/32, 232.8.8.8), S-bit > Join > R1(config)# > *Mar 1 01:20:27.907: PIM(0): Send v2 join/prune to 215.1.9.9 > (FastEthernet0/0.19) > R1(config)# > > r6 > --- > > R6(config)# > *Mar 1 01:20:28.439: PIM(0): Received v2 Register on FastEthernet0/0.16 > from 215.5.9.5 > *Mar 1 01:20:28.439: for 215.0.0.5, group 232.8.8.8 > *Mar 1 01:20:28.447: PIM(0): Insert (215.0.0.5,232.8.8.8) join in nbr > 215.1.6.1's queue > *Mar 1 01:20:28.447: PIM(0): Forward decapsulated data packet for > 232.8.8.8 on Loopback0 > *Mar 1 01:20:28.447: PIM(0): Building Join/Prune packet for nbr 215.1.6.1 > *Mar 1 01:20:28.447: PIM(0): Adding v2 (215.0.0.5/32, 232.8.8.8), S-bit > Join > *Mar 1 01:20:28.447: PIM(0): Send v2 join/prune to 215.1.6.1 > (FastEthernet0/0.16) > R6(config)#do un all > All possible debugging has been turned off > R6(config)# > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > > http://onlinestudylist.com/mailman/listinfo/ccie_rs > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > > http://onlinestudylist.com/mailman/listinfo/ccie_rs -- // Freedom Matters // CCIE #29189 // www.packet-forwarding.net _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
