Multicast Lab
Overview
Multicast routing is a networking method for efficient distribution of one-to-many traffic. A multicast source, such as a live video conference, sends traffic in one stream to a multicast group. The multicast group contains receivers such as computers, devices, and IP phones.
Common uses include these technologies:
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Voice over IP (VOIP)
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Video on demand (VOD)
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Video conferencing
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IP television (IPTV)
Base Configuration
Address the network as per topology above, configure loopbacks on each of the backbone routers, run and IGP to advertise everything everywhere, disable "ip routing" on the MCAST-SRC and the Receiver and configure default-gateways to establish IP connectivity between Receiver and MCAST-SRC
Multicast Common
PIM Sparse Mode
PIM Dense Mode
on each router that is participating in multicast, configure;
ip multicast-routing
on each routers interface that is participating in multicast, configure;
interface range gi0/0-2
ip pim dense-mode
Send and Receive traffic
On MCAST-SRC - ping a multicast address
MCAST-SRC#ping 239.1.1.1 repeat 99999999
On Receiver - join the group!
Receiver(config-if)#ip igmp join-group 239.1.1.1
TIP:Check the ip mroute table on R3 to confirm the entry
on each router participating in multicast, statically configure the RV address (R2s Loopback)
ip pim rp-address 2.2.2.2
Then change the interface pim mode to sparse-mode;
interface range gi0/0-2
ip pim sparse-mode
in addition, on the lo0 of the RV, enable it too;
int lo0
ip pim sparse-mode
PIM Sparse-Dense Mode
on each router, remove the RV reference
no ip pim rp-address 2.2.2.2
on each router interface participating in multicast, change the pim mode to sparse-dense mode
interface range gi0/0-2
ip pim sparse-dense mode
in addition, on the lo0 of the RV, change it too;
int lo0
ip pim sparse-dense mode
now again, on the RV, announce to the world that it is the RV!
ip pim send-rp-announce lo0 scope 16
And set as the mapping agent;
ip pim send-rp-discover scope 16
Verification
show ip mroute
Notes
224.0.0.0 239.255.255.255 - Multicast Range of address space
224.0.0.0 224.0.0.255 - reserved for link local addresses
224.0.1.0 238.255.255.255 - globally scoped addresses
232.0.0.0 232.255.255.255 - source specific addresses
233.0.0.0 233.255.255.255 - GLOP Addresses tied to AS Number
239.0.0.0 239.255.255.255 - Limited Scope Addresses - private use
IGMP (internet group management protocol)
igmpv1 rcv - no proactive means to cancel subscription - the upstream IGMP router will poll it every 60 seconds - do you still want to join?
igmpv2 rcv - can proactivly leave subscription
An intermediate switch needs to run IGMP snooping so it can maintain a db similar to dhcp snooping
igmpv3 you can request a join from a multicast group, but mandate that it must come from a specific IP (normal IP)
Reverse Path Forwarding - prevents duplicate packets by rcv checks routing table to see what interfaces it should recieve replies from
PIM - protocol independant multicast
DM - dense mode - source distribution tree - flood and prune model - prunes off unnecessary links - grafts are sent to join again
SM - sparce mode - best practice - shared distribution tree - RV - join requests sent to RV - initial traffic sent to RV and relayed, then direct join with source address of sender - then the IGMP router prunes connection to RV - shortest path tree switchover