Lab Objective:
The focus of this lab is to understand IP Multicast Sparse Mode forwarding in Cisco IOS routers. Additional technologies include Internet Group Management Protocol (IGMP).
Lab Topology:
The lab network topology is illustrated below:
|
IMPORTANT NOTE If you are using the www.howtonetwork.net racks, please bring up the LAN interfaces connected to the routers by issuing the no shutdown command on the connected switches. If you are using a home lab with no interface fastethernet 0/0 Alternately, you can simply connect the interfaces to a hub or switch if you have one available in your own lab. |
Task 1
Configure the hostnames, IP addressing on all routers as illustrated in the network topology.
Task 2
Enable EIGRP on all routers as illustrated in the topology. Verify your EIGRP configuration.
Task 3
Enable Internet Group Management Protocol on the LAN interfaces of R1 and R4. These LAN interfaces are connected to legacy hosts that only understand basic IGMP. Configure the version that provides the most basic services. Finally, enable Sparse Mode forwarding on the router LAN interfaces. Verify your solution using the appropriate commands.
Task 4
Enable Sparse Mode forwarding on all router WAN interfaces. Verify your configuration using the appropriate commands.
Task 5
Configure R1 so that its LAN interface is joined to Multicast group 227.1.1.1. Configure R4 so that its LAN interface is joined to Multicast group 227.4.4.4. Verify that R1 can ping R4s Multicast group and that R4 can ping R1s Multicast group.
Task 6
Given that the network will be running Sparse Mode, configure R2 as the Rendezvous Point, or RP. Configure a Loopback 0 interface with the IP address 2.2.2.2/32 on this router. This Loopback address should be configured as the RP for all routers in the network. HINT: Use the ip pim rp-address <address> command on all routers. Verify your configuration and test you solution by pinging 227.4.4.4 from R1 and 227.1.1.1 from R4.
Lab Validation
Task 1
Please refer to previous tasks for basic VLAN and IP addressing configuration. These will not be included in this section for brevity and to avoid being redundant.
Task 2
Please refer to previous labs for basic EIGRP configuration. Following this, verify your EIGRP configuration using the show ip eigrp neighbors andshow ip route commands. Following this configuration, your route tables should show the following route information:
| R1#show ip route eigrp 10.0.0.0/30 is subnetted, 3 subnets D 10.0.0.8 [90/2681856] via 10.0.0.2, 00:00:12, Serial0/0 D 10.0.0.12 [90/21536000] via 10.0.0.2, 00:00:12, Serial0/0 150.4.0.0/24 is subnetted, 1 subnets D 150.4.4.0 [90/21538560] via 10.0.0.2, 00:00:12, Serial0/0 |
| R2#show ip route eigrp 10.0.0.0/30 is subnetted, 3 subnets D 10.0.0.12 [90/21024000] via 10.0.0.10, 00:00:22, Serial0/1 150.1.0.0/24 is subnetted, 1 subnets D 150.1.1.0 [90/2172416] via 10.0.0.1, 00:00:17, Serial0/0 150.4.0.0/24 is subnetted, 1 subnets D 150.4.4.0 [90/21026560] via 10.0.0.10, 00:00:22, Serial0/1 |
| R3#show ip route eigrp 10.0.0.0/30 is subnetted, 3 subnets D 10.0.0.0 [90/21024000] via 10.0.0.9, 00:00:25, Serial1/1 150.1.0.0/24 is subnetted, 1 subnets D 150.1.1.0 [90/21026560] via 10.0.0.9, 00:00:20, Serial1/1 150.4.0.0/24 is subnetted, 1 subnets D 150.4.4.0 [90/20514560] via 10.0.0.14, 00:00:31, Serial1/2 |
| R4#show ip route eigrp 10.0.0.0/30 is subnetted, 3 subnets D 10.0.0.8 [90/21024000] via 10.0.0.13, 00:00:34, Serial0/0 D 10.0.0.0 [90/21536000] via 10.0.0.13, 00:00:28, Serial0/0 150.1.0.0/24 is subnetted, 1 subnets D 150.1.1.0 [90/21538560] via 10.0.0.13, 00:00:23, Serial0/0 |
Task 3
The core requirement of this task is straightforward. IGMPv1 provides the most basic services. Given this understanding, this task is completed as follows:
| R1(config)#ip multicast-routing R1(config)#interface fastethernet 0/0 R1(config-if)#ip igmp version 1 R1(config-if)#ip pim sparse-mode R1(config-if)#exit |
| R4(config)#ip multicast-routing R4(config)#interface fastethernet 0/0 R4(config-if)#ip igmp version 1 R4(config-if)#ip pim sparse-mode R4(config-if)#exit |
Next, verify your configuration using the show ip igmp interface command:
| R1#show ip igmp interface fastethernet 0/0 FastEthernet0/0 is up, line protocol is up Internet address is 150.1.1.1/24 IGMP is enabled on interface Current IGMP host version is 1 Current IGMP router version is 1 IGMP query interval is 60 seconds Inbound IGMP access group is not set IGMP activity: 0 joins, 0 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is 150.4.4.4 IGMP querying router is 150.4.4.4 (this system) No multicast groups joined by this system |
| R4#show ip igmp interface fastethernet 0/0 FastEthernet0/0 is up, line protocol is up Internet address is 150.4.4.4/24 IGMP is enabled on interface Current IGMP host version is 1 Current IGMP router version is 1 IGMP query interval is 60 seconds Inbound IGMP access group is not set IGMP activity: 0 joins, 0 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is 150.4.4.4 (this system) IGMP querying router is 150.4.4.4 (this system) No multicast groups joined by this system |
Notice that unlike Dense Mode, the interfaces are NOT automatically joined to any Multicast groups. This is because Sparse mode forwarding operates in a manner that is opposite to dense mode forwarding. That is, while dense mode assumes that all Multicast-enabled interfaces are interested in receiving Multicast packets unless explicitly configured otherwise, sparse mode assumes that no Multicast interfaces are interested in receiving Multicast packets unless explicitly configured otherwise; that is to say, unless a PIM join message is received on the interface. As such, routers in a sparse-mode network must explicitly request that the data stream be forwarded to them.
Task 4
The requirements of this task are straightforward. This task is completed as follows:
| R1(config)#interface serial 0/0 R1(config-if)#ip pim sparse-mode R1(config-if)#exit |
| R2(config)#ip multicast-routing R2(config)#interface serial 0/0 R2(config-if)#ip pim sparse-mode R2(config-if)#exit R2(config)#interface serial 0/1 R2(config-if)#ip pim sparse-mode R2(config-if)#exit |
| R3(config)#ip multicast-routing R3(config)#interface serial 1/1 R3(config-if)#ip pim sparse-mode R3(config-if)#exit R3(config)#interface serial 1/2 R3(config-if)#ip pim sparse-mode R3(config-if)#exit |
| R4(config)#interface serial 0/0 R4(config-if)#ip pim sparse-mode R4(config-if)#exit |
Next, verify PIM Sparse Mode parameters using the show ip pim interface command:
| R1#show ip pim interface serial 0/0 detail Serial0/0 is up, line protocol is up Internet address is 10.0.0.1/30 Multicast switching: fast Multicast packets in/out: 667/1 Multicast TTL threshold: 0 PIM: enabled PIM version: 2, mode: sparse PIM DR: 0.0.0.0 PIM neighbor count: 1 PIM Hello/Query interval: 30 seconds PIM Hello packets in/out: 61/63 PIM State-Refresh processing: enabled PIM State-Refresh origination: disabled PIM NBMA mode: disabled PIM ATM multipoint signalling: disabled PIM domain border: disabled Multicast Tagswitching: disabled |
Task 5
To configure a router interface to join a Multicast group, a technique commonly used to test the Multicast configuration, use the ip igmp join-group <group> interface command:
| R1(config)#interface fastethernet 0/0 R1(config-if)#ip igmp join-group 227.1.1.1 R1(config-if)#exit |
| R4(config)#interface fastethernet 0/0 R4(config-if)#ip igmp join-group 227.4.4.4 R4(config-if)#exit |
Next, verify your configuration using the show ip igmp interface command:
| R1#show ip igmp interface fastethernet 0/0 FastEthernet0/0 is up, line protocol is up Internet address is 150.1.1.1/24 IGMP is enabled on interface Current IGMP host version is 1 Current IGMP router version is 1 IGMP query interval is 60 seconds Inbound IGMP access group is not set IGMP activity: 2 joins, 0 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is 150.4.4.4 IGMP querying router is 150.4.4.4 Multicast groups joined by this system (number of users): 227.1.1.1(1) |
| R4#show ip igmp interface fastethernet 0/0 FastEthernet0/0 is up, line protocol is up Internet address is 150.4.4.4/24 IGMP is enabled on interface Current IGMP host version is 1 Current IGMP router version is 1 IGMP query interval is 60 seconds Inbound IGMP access group is not set IGMP activity: 3 joins, 0 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is 150.4.4.4 (this system) IGMP querying router is 150.4.4.4 (this system) Multicast groups joined by this system (number of users): 227.4.4.4(1) |
Task 6
When sparse-mode is enabled, one of the routers in the network performs a special function as a connection point between the source and the receiver. This router is referred to as the Rendezvous Point, or RP. The RP combines knowledge of the group source with the requests from the receiver. The RP is where the sender and the receiver first meet before the shortest-path tree is established. In other words, once the sender and receiver are aware of each other via the use of the RP, they use the shortest path between sender and receiver, based on routing protocol metric, to send and receive Multicast packets.
Once the Multicast traffic from the source and the requests from the receivers connect at the RP, the traffic is forwarded through the network. This shared tree has the RP at the top of the forwarding tree with the network segments and receivers as the branches and leaves, respectively. This is often referred to as the Rendezvous Point Tree (RPT). The shared-tree used by sparse mode is represented with the (*, G) notation. The * is used as a wildcard because the actual source of the Multicast stream is never known until registered with the RP.
In Cisco IOS Software, there are three ways in which the location of the RP can be specified:
- By statically configuring the router or switch with the RP IP address
- Automatically, using the Cisco Auto-RP mechanism
- Automatically, using the Bootstrap Router mechanism with PIMv2
This task requires that you statically configure the RP address on all routers using the ip pim rp-address <address> command. This task is completed as follows:
| R1(config)#ip pim rp-address 2.2.2.2 |
| R2(config)#interface loopback 0 R2(config-if)#ip address 2.2.2.2 255.255.255.255 R2(config-if)#ip pim sparse-mode R2(config-if)#exit R2(config)#ip pim rp-address 2.2.2.2 R2(config)#exit |
NOTE: You MUST advertise the Loopback 0 interface via EIGRP. If you enabled EIGRP for all networks using the network 0.0.0.0 command, no additional configuration is necessary. However, if you explicitly enabled EIGRP for specific subnets, you need to also advertise the configured Loopback 0 interface via EIGRP; otherwise, no other router can reach this address.
| R3(config)#ip pim rp-address 2.2.2.2 |
| R4(config)#ip pim rp-address 2.2.2.2 |
Next, verify static RP configuration using the show ip pim rp command:
| R1#show ip pim rp Group: 227.4.4.4, RP: 2.2.2.2, uptime 00:02:09, expires never Group: 227.1.1.1, RP: 2.2.2.2, uptime 00:00:47, expires never Group: 224.0.1.40, RP: 2.2.2.2, uptime 00:02:09, expires never |
| R2#show ip pim rp Group: 227.4.4.4, RP: 2.2.2.2, next RP-reachable in 00:00:52 Group: 227.1.1.1, RP: 2.2.2.2, next RP-reachable in 00:00:16 Group: 224.0.1.40, RP: 2.2.2.2, next RP-reachable in 00:01:21 |
| R3#show ip pim rp Group: 227.4.4.4, RP: 2.2.2.2, uptime 00:02:18, expires never Group: 227.1.1.1, RP: 2.2.2.2, uptime 00:01:24, expires never Group: 224.0.1.40, RP: 2.2.2.2, uptime 00:02:21, expires never |
| R4#show ip pim rp Group: 227.4.4.4, RP: 2.2.2.2, uptime 00:02:30, expires never Group: 227.1.1.1, RP: 2.2.2.2, uptime 00:01:36, expires never Group: 224.0.1.40, RP: 2.2.2.2, uptime 00:02:30, expires never |
In addition to the two statically defined Multicast groups, also notice that group 224.0.1.40 is also listed in the output of this command. This is the group address used for RP Discovery messages. This group is enabled by default as is used for RP Discovery. Finally, complete the task by pinging 227.4.4.4 from R1 and 227.1.1.1 from R4:
| R1#ping 227.4.4.4
Type escape sequence to abort. Reply to request 0 from 10.0.0.14, 32 ms |
| R4#ping 227.1.1.1
Type escape sequence to abort. Reply to request 0 from 10.0.0.1, 48 ms |
Final Router Configurations
R1
|
R1#term len 0 Current configuration : 1014 bytes R1# |
R2
|
R2#term len 0 Current configuration : 1012 bytes R2# |
R3
|
R3#term len 0 Current configuration : 1275 bytes R3# |
R4
|
R4#term len 0 Current configuration : 983 bytes R4# |