rivc1982

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About rivc1982

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  1. Originally posted in CCNP section and no response yet: From all the studying I have done I have interpreted that when an interface in a cisco router is configured for one mode or the other, that is the way it will handle multicast traffic. As I read and try to fully grasp multicasting I usually run into a wall where things just don't make any sense. Here is my situation: Router A has fa0/0 interface to Router B fa0/0 (both ends configured in PIM sparse-mode). Router A has a static join for a multicast group 239.192.10.100. Router B is the BSR and the RP for the group. Router B has one link to another router with it configured in stricly PIM dense-mode. Why is it that when I perform a show ip mroute on router B it shows the (*,G) with an outgoing interface of both the sparse and the dense mode interface? From all my reading (which doesn't really talk about operating multiple router interfaces in different modes in depth) I figured if there was an RP then the shared tree would extend from the receiver toward the RP and stop. Why does it also list the dense mode interface in the outgoing interface list? Anybody know where I can find an explanation in writing? Please note I did this in GNS3. Is it a bug? Below are my configs and findings. Router A ip multicast-routing ! interface FastEthernet0/0 Description Link to Router 2 ip address 192.168.12.1 255.255.255.0 ip pim sparse-mode ip igmp join-group 239.192.10.100 duplex auto speed auto ! router ospf 1 log-adjacency-changes network 0.0.0.0 255.255.255.255 area 0 ! Router B ip multicast-routing ! interface Loopback0 ip address 1.1.1.1 255.255.255.255 ip pim sparse-mode ! interface FastEthernet0/0 Description Link to Router A ip address 192.168.12.2 255.255.255.0 ip pim sparse-mode duplex auto speed auto ! interface FastEthernet1/0 ip address 192.168.23.2 255.255.255.0 ip pim bsr-border ip pim dense-mode duplex auto speed auto ! router ospf 1 log-adjacency-changes network 0.0.0.0 255.255.255.255 area 0 ! ip forward-protocol nd ! ! ip pim bsr-candidate Loopback0 0 ip pim rp-candidate Loopback0 group-list 10 priority 20 ! access-list 10 permit 239.192.10.101 Router A#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, 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 Outgoing interface flags: H - Hardware switched, A - Assert winner Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode (*, 239.192.10.100), 00:00:01/00:02:58, RP 1.1.1.1, flags: SJPL Incoming interface: FastEthernet0/0, RPF nbr 192.168.12.2 Outgoing interface list: Null (*, 224.0.1.40), 00:00:01/00:02:58, RP 0.0.0.0, flags: DPL Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: Null Router B#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, 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 Outgoing interface flags: H - Hardware switched, A - Assert winner Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode (*, 239.192.10.100), 00:00:03/00:02:56, RP 1.1.1.1, flags: SJC Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: FastEthernet1/0, Forward/Dense, 00:00:03/00:00:00 FastEthernet0/0, Forward/Sparse, 00:00:03/00:02:56 (*, 224.0.1.40), 00:00:51/00:02:53, RP 0.0.0.0, flags: DCL Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: FastEthernet1/0, Forward/Dense, 00:00:52/00:00:00 FastEthernet0/0, Forward/Sparse, 00:00:52/00:02:52 Loopback0, Forward/Sparse, 00:00:52/00:02:42
  2. From all the studying I have done I have interpreted that when an interface in a cisco router is configured for one mode or the other, that is the way it will handle multicast traffic. As I read and try to fully grasp multicasting I usually run into a wall where things just don't make any sense. Here is my situation: Router A has fa0/0 interface to Router B fa0/0 (both ends configured in PIM sparse-mode). Router A has a static join for a multicast group 239.192.10.100. Router B is the BSR for the segment and the RP for the group. Router B has one link to another router with it configured in stricly PIM dense-mode. Why is it that when I perform a show ip mroute on router B it shows the (*,G) with an outgoing interface of both the sparse and the dense mode interface? From all my reading (which doesn't really talk about operating multiple router interfaces in different modes in depth) I figured if there was an RP then the shared tree would extend from the receiver toward the RP and stop. Why does it also list the dense mode interface in the outgoing interface list? Anybody know where I can find an explanation in writing? Please note I did this in GNS3. Is it a bug? Below are my configs and findings. Router A ip multicast-routing ! interface FastEthernet0/0 Description Link to Router 2 ip address 192.168.12.1 255.255.255.0 ip pim sparse-mode ip igmp join-group 239.192.10.100 duplex auto speed auto ! router ospf 1 log-adjacency-changes network 0.0.0.0 255.255.255.255 area 0 ! Router B ip multicast-routing ! interface Loopback0 ip address 1.1.1.1 255.255.255.255 ip pim sparse-mode ! interface FastEthernet0/0 Description Link to Router A ip address 192.168.12.2 255.255.255.0 ip pim sparse-mode duplex auto speed auto ! interface FastEthernet1/0 ip address 192.168.23.2 255.255.255.0 ip pim bsr-border ip pim dense-mode duplex auto speed auto ! router ospf 1 log-adjacency-changes network 0.0.0.0 255.255.255.255 area 0 ! ip forward-protocol nd ! ! ip pim bsr-candidate Loopback0 0 ip pim rp-candidate Loopback0 group-list 10 priority 20 ! access-list 10 permit 239.192.10.101 Router A#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, 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 Outgoing interface flags: H - Hardware switched, A - Assert winner Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode (*, 239.192.10.100), 00:00:01/00:02:58, RP 1.1.1.1, flags: SJPL Incoming interface: FastEthernet0/0, RPF nbr 192.168.12.2 Outgoing interface list: Null (*, 224.0.1.40), 00:00:01/00:02:58, RP 0.0.0.0, flags: DPL Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: Null Router B#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, 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 Outgoing interface flags: H - Hardware switched, A - Assert winner Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode (*, 239.192.10.100), 00:00:03/00:02:56, RP 1.1.1.1, flags: SJC Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: FastEthernet1/0, Forward/Dense, 00:00:03/00:00:00 FastEthernet0/0, Forward/Sparse, 00:00:03/00:02:56 (*, 224.0.1.40), 00:00:51/00:02:53, RP 0.0.0.0, flags: DCL Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: FastEthernet1/0, Forward/Dense, 00:00:52/00:00:00 FastEthernet0/0, Forward/Sparse, 00:00:52/00:02:52 Loopback0, Forward/Sparse, 00:00:52/00:02:42
  3. I'd recommend picking up a study guide to go along with the cert guide. IMO the cert guide roughly covers the topics within. I am always looking for further details on the internet because of this. The study guides are more in depth. GNS3 is the best simulator I have used. For labs I used Cisco PEC that I have access through my company and just trial and error from testing the information I have read.
  4. Look at the diagram. Because RTE is directly connected to RTB. The dotted line in the middle indicates that RTB and RTA are iBGP neighbours. However, for two routers to be iBGP neighbours they do NOT need to be directly connected; they can rely on an IGP (such as OSPF, EIGRP, RIP, etc) to route traffic between each other. So in order for RTB to reach 170.10.0.0 the traffic is sent to RTE, then to RTA then finally on to RTC. Now the next hop advertised for 170.10.0.0 is 2.2.2.1, RTB will recieve the update about 170.10.0.0 with next hop 2.2.2.1. Unless RTB knows how to get to the next hop address 2.2.2.1 it will not put this route into the Routing table. It will however store the router in its BGP table as inaccessible (If someone reads this please confirm for me). So if RTE, RTA & RTB are running an IGP and RTA includes interface 2.2.2.1 in its updates RTB will see the next hop of the BGP route in its routing table thus meeting the synchronization rule. IF NOT you can add a static route to 2.2.2.1 pointing at RTE and meet the synchronization rule Hope that makes sense. Ahh... my mistake. I though the dotted line was a physical connection not logical.. Thanx!
  5. Hi guys, I was going over the synchronization rule on the Cisco website and I understand the reasoning behind the rule for the transit AS but I was confused by something else. Your assistance would greatly appreciated. http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c95bb.shtml#synch The first sentance says: Before the discussion of synchronization, look at this scenario. RTC in AS300 sends updates about 170.10.0.0. RTA and RTB run iBGP, so RTB gets the update and is able to reach 170.10.0.0 via next hop 2.2.2.1. Remember that the next hop is carried via iBGP. In order to reach the next hop, RTB must send the traffic to RTE. Why must RTB send traffic to 170.10.0.0 via RTE? Why can't it just send it via the direct iBGP connection?