Multicast Routing -Part 4 (Lab )
Priyanka Shyam
Network Geek with a robust skill set | CCDE (Written) | CCIE | CWNA | Cisco SCOR | Cisco SD-WAN Expert | Technical Writer | Multitasker | Considerate & Empathic Communicator
Hello Friends,
This is a continuation of my previous article Multicast Routing Part-3 and also the last part of the multicast where I would be doing a very simple lab to demonstrate the multicast traffic.
So below is my topology:
Where I am using 2 Cisco CAT 3850 Switch and 1 Cisco CAT 6880 switch which I am using as a router.
As this is a small setup so I will use one of my switches as the source and the other switch as the receiver.
Multicast Configuration
Below is the prerequisite for the multicast configuration :
Fully converged unicast routing it means there should be reachability among all the devices in the network. So first the unicast reachability should be there then multicast will come into the picture.
I can show you the same, you can see from below output that I have the reachability among my devices.
F340.04.02-3800-2#ping 192.168.2.4 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.2.4, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms F340.04.02-3800-2#ping 192.168.2.5 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.2.5, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/2 ms F340.04.02-3800-2# F340.04.02-3800-1#ping 192.168.1.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.3, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/2 ms F340.04.02-3800-1# F340.04.02-3800-1# F340.04.02-3800-1#ping 192.168.2.4 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.2.4, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms F340.04.02-3800-1# Router#ping 192.168.2.5 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.2.5, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms Router#ping 192.168.1.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms Router#
>>Enable multicast routing on the relevant routers
Router#show running-config | inc routing
ip multicast-routing
F340.04.02-3800-2#show running-config | inc routing ip multicast-routing F340.04.02-3800-1#show running-config | inc routing ip multicast-routing
>>Enable PIM on the relevant interfaces
If unrestricted enable PIM on all
>>RP configuration (Peer to peer communication can be through static, BSR or auto RP).
>>If you have given a choice then use BSR its open-source pool
>>Join groups where needed and test (IP IGMP join-group)using the ping group address.
F340.04.02-3800-2#show running-config interface gigabitEthernet 2/0/1 Building configuration... Current configuration : 121 bytes ! interface GigabitEthernet2/0/1 no switchport ip address 192.168.1.2 255.255.255.0 ip igmp join-group 239.1.1.1 end
Again I am pointing out the very first point that is fully converged unicast routing. Now this is going to be the number one issue you are going to face the issue you think that you have a multicast problem but there will be a unicast problem Because the unicast routing table will be used by the RP (Rezendous Point) for the Verification.
Configuration of the different used components in the above diagram:
Router#show running-config interface TenGigabitEthernet5/1 Building configuration... Current configuration : 111 bytes ! interface TenGigabitEthernet5/1 ip address 192.168.1.3 255.255.255.0 ip pim dense-mode no cdp enable end Router#show running-config interface tenGigabitEthernet 5/3 Building configuration... Current configuration : 111 bytes ! interface TenGigabitEthernet5/3 ip address 192.168.2.4 255.255.255.0 ip pim dense-mode no cdp enable end F340.04.02-3800-1#show running-config interface gigabitEthernet 2/0/4 Building configuration... Current configuration : 110 bytes ! interface GigabitEthernet2/0/4 no switchport ip address 192.168.2.5 255.255.255.0 ip pim dense-mode end F340.04.02-3800-1#show running-config interface gigabitEthernet 2/0/3 Building configuration... Current configuration : 110 bytes ! interface GigabitEthernet2/0/3 no switchport ip address 192.168.3.6 255.255.255.0 ip pim dense-mode end F340.04.02-3800-2#show running-config interface gigabitEthernet 2/0/1 Building configuration... Current configuration : 121 bytes ! interface GigabitEthernet2/0/1 no switchport ip address 192.168.1.2 255.255.255.0 ip igmp join-group 239.1.1.1 end Router#show ip interface brief | inc up TenGigabitEthernet5/1 192.168.1.3 YES manual up up TenGigabitEthernet5/3 192.168.2.4 YES manual up up mgmt0 unassigned YES NVRAM up up Router# F340.04.02-3800-1#show ip interface brief | inc up GigabitEthernet0/0 unassigned YES NVRAM up up GigabitEthernet2/0/3 192.168.3.6 YES manual up up GigabitEthernet2/0/4 192.168.2.5 YES manual up up Tunnel0 unassigned YES unset up down F340.04.02-3800-1# F340.04.02-3800-2#show ip interface brief | inc up Vlan3 10.0.0.2 YES NVRAM up down GigabitEthernet0GigabitEthernet0/0 10.122.161.40 YES DHCP up up GigabitEthernet2/0/1 192.168.1.2 YES manual up up F340.04.02-3800-2#
Everything is done all the configuration. So let me ping the multicast IP from the source
F340.04.02-3800-1#ping 239.1.1.1 Type escape sequence to abort. Sending 1, 100-byte ICMP Echos to 239.1.1.1, timeout is 2 seconds:
Now let's checks the show ip mroute on the router.
Router#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, 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, G - Received BGP C-Mroute, g - Sent BGP C-Mroute, N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed, Q - Received BGP S-A Route, q - Sent BGP S-A Route, V - RD & Vector, v - Vector, p - PIM Joins on route, x - VxLAN group, c - PFP-SA cache created entry Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode (*, 239.1.1.1), 00:25:55/stopped, RP 0.0.0.0, flags: DC Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: TenGigabitEthernet5/1, Forward/Dense, 00:25:55/stopped TenGigabitEthernet5/3, Forward/Dense, 00:25:55/stopped (192.168.2.5, 239.1.1.1), 00:01:05/00:01:54, flags: T Incoming interface: TenGigabitEthernet5/3, RPF nbr 192.168.2.5 Outgoing interface list: TenGigabitEthernet5/1, Forward/Dense, 00:01:05/stopped (*, 224.0.1.40), 00:26:44/00:02:08, RP 0.0.0.0, flags: DCL Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: TenGigabitEthernet5/3, Forward/Dense, 00:26:44/stopped
We can see s.g entry that is nothing but the source-specific and we have also *, G entry that is for any source which belongs to that multicast group.
For every s,g entry there will the corresponding *, G entry.
We can also look into this output and check what is the ingress port for the multicast traffic. We can see that the incoming interface for the (S,G )entry is Te 5/3.We can also see our outgoing interface is Te 5/4.And finally, notice the flags T on (S,G )entry just notice that we don’t have J flag set. The J flag says that we have joined the shortest path tree. We are using a shortest-path tree but because we are using dense mode we started that with the shortest path tree we did not have to join it.