Multicast: DVMRP

How to locate in DocCD ?
Configuration Guide -->Cisco IOS IP Multicast Configuration Guide, Release 12.4T-->Configuring DVMRP Interoperability

Two things to remember
1) Create a Tunnel from Router to the Unix host, use source int = directly connected int = fasx/x
tunnel dest = unix server IP

2) Advertise the directly connected subnet ( or for that matter any subnet) via ACL and this cmd
ip dvmrp metric 2 list 10

10 = ACL for the subnet to be adv
2 = metric

Multicast: ip multicast ttl-threshold x

Trackback

Some references in Blogs here

basically, the TTL of packet received should be higher than the TTL threshold configured

So if the config is as follows
PE3(config)#int f0/0.13
PE3(config-subif)#ip mul
PE3(config-subif)#ip multicast tt
PE3(config-subif)#ip multicast ttl-threshold 9
PE3(config-subif)#

Then any incoming multicast packet with TTL=10 or greater will be forwarded.
Any incoming multicast packet with TTL=9 or lesser will be discarded.

Multicast: Rate Limit Multicast Traffic

Nice GroupStudy Observation

Some references in the blog here and here


PE1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
PE1(config)#int f0/0.21
PE1(config-subif)#ip multicast rate-limit out 200
PE1(config-subif)#^Z
PE1#
5d20h: %SYS-5-CONFIG_I: Configured from console by console
PE1#sh ip mro
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
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

(*, 224.0.1.39), 01:45:58/stopped, RP 0.0.0.0, flags: DC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
FastEthernet0/0.31, Forward/Sparse-Dense, 01:45:58/00:00:00
FastEthernet0/0.21, Forward/Sparse-Dense, 01:45:58/00:00:00, Int limit 200 kbps

(10.1.1.1, 224.0.1.39), 01:45:10/00:02:49, flags: T
Incoming interface: Loopback0, RPF nbr 0.0.0.0
Outgoing interface list:
FastEthernet0/0.21, Forward/Sparse-Dense, 01:45:10/00:00:00, Int limit 200 kbps
FastEthernet0/0.31, Forward/Sparse-Dense, 01:45:10/00:00:00

Multicast: ip pim accept-register list

SSM : Source Specific Multicast
=> Allow only certain sources to register with RP.

Trackback

Merge this with the allowing access only to Even Multicast Group via modifying this ACL
and you get following.

ip access-list extended SSM
deny ip host 10.23.1.1 229.0.0.1 0.0.0.254
permit ip any any

ip pim accept-register list SSM

This way 10.23.1.1 will not be able to register with RP for odd groups in 229.0.0.x multicast groups. Rest (even and anything else) is allowed

Multicast: ip pim neighbor-filter : Stub Multicast Routing:

Stub Multicast Routing
Why ?
1) Save Upstream Router's Resources as the downstream Router doesnt participate in PIM anymore.....
2) Save RP's Resources as the downstream Router doesnt participate in PIM anymore.....
3) Security: Downstream Router now unaware of your RPs, Cannot advertise his groups to RP.
4) Security: Downstream Router cannot be the DR as well, since DR is elected via PIM. So you control who becomes the DR on a broadcast segment.

How ?

Receivers<--(f0/1)CE8 (f0/0)--(f0/0.82)PE2-->RP
PE2#sh run int f0/0.82
Building configuration...

Current configuration : 148 bytes
!
interface FastEthernet0/0.82
encapsulation dot1Q 82
ip address 10.82.1.2 255.255.255.0
ip pim neighbor-filter 3
ip pim sparse-dense-mode
end

PE2#

PE2#sh access-l 3
Standard IP access list 3
10 deny 10.82.1.1 (89 matches) --> This is the IP address of the CE8 interface f0/0
20 permit any
PE2#

By filtering off CE8, we no more have PIM neighborship with him on interface f0/0.82
Now CE8 cannot communicate with the Upstream Multicast Senders.

To enable this we have to conf following on CE8 where receivers are located ( int f0/1)
CE8 now communicates with PE2 via PIM Dense mode.
All traffic in CE8 is dense.

CE8#sh run int f0/1
Building configuration...

Current configuration : 349 bytes
!
interface FastEthernet0/1
ip igmp helper-address 10.82.1.2
CE8#

Multicast: sh ip pim rp output

Sh ip pim rp output
PE3#sh ip pim rp
Group: 235.235.235.235, RP: 10.1.1.3, v2, v1, next RP-reachable in 00:00:28
Group: 224.2.2.2, RP: 10.1.1.3, next RP-reachable in 00:00:34
Group: 225.2.2.2, RP: 10.1.1.3, v2, v1, next RP-reachable in 00:01:28
PE3#

the ones with v2,v1,next RP-reachable are the entries for which we are the RP.
But to tell if this was via static or Auto-RP, we have to do sh ip pim rp mappings

PE3#sh ip pim rp ma
PIM Group-to-RP Mappings
This system is an RP (Auto-RP)

Group(s) 225.2.2.2/32
RP 10.1.1.3 (?), v2v1
Info source: 10.1.1.2 (?), elected via Auto-RP
Uptime: 00:11:30, expires: 00:02:26
Group(s) 225.8.8.8/32
RP 10.1.1.2 (?), v2v1
Info source: 10.1.1.2 (?), elected via Auto-RP
Uptime: 00:15:24, expires: 00:02:26
Group(s) 229.0.0.1/32
RP 10.1.1.2 (?), v2v1
Info source: 10.1.1.2 (?), elected via Auto-RP
Uptime: 00:15:24, expires: 00:02:26
Group(s) 235.0.0.0/8
RP 10.1.1.3 (?), v2v1
Info source: 10.1.1.2 (?), elected via Auto-RP
Uptime: 00:06:30, expires: 00:02:27
Acl: 1, Static
RP: 10.1.1.3 (?)
PE3#
PE3#sh access-l 1
Standard IP access list 1
10 permit 224.2.2.2 (39514 matches)
PE3#

Multicast: ip pim query-interval and ip igmp query-inerval

ip igmp query-interval is used to query the reports to find out if any receivers are still active on the LAN segment

ip pim query-interval is used to send PIM Hello updates

Multicast: Hosts that dont support IGMP

If there are hosts that dont support IGMP on a LAN Segment.
The router connecting that LAN segment can join IGMP group statically on their behalf

int f0/0
ip igmp static-group 235.1.1.1

Here if we ran a ping 235.1.1.1 from the source, the Router will not respond only the receivers ( End Hosts) will respond.

Whereas in the igmp join-group, even the router's interface responds.

Also (*,G) entry for join-group will have flags C (Connected) & L(Local)
The static-group will have flags C (Connected) only..

address-family ipv4 multicast

AS per CCO

https://www.cisco.com/en/US/docs/ios/12_1/iproute/command/reference/1rdmbgp.pdf

TO enable Multicast BGP (MBGP)

router bgp 200
address-family ipv4 multicast
neighbor 20.6.26.2 activate
network 20.6.5.5 mask 255.255.255.255

How to verify
sh ip bgp ipv4 multicast

MSDP

ip msdp peer connect-source lo0
ip msdp default-peer

ip pim accept-rp

From CCO

http://www.cisco.com/en/US/docs/ios/12_2/ipmulti/command/reference/1rfmult2.html#wp1019380

ip pim accept-rp

To configure a router to accept join or prune messages destined for a specified rendezvous point (RP) and for a specific list of groups, use the ip pim accept-rp command in global configuration mode. To remove that check, use the no form of this command.

rp-address

RP address of the RP allowed to send join messages to groups in the range specified by the group access list.