[c-nsp] Multicast Questions - New Setup

[Brant I. Stevens]

On 12/7/06 3:19 PM, "Paul Stewart" <pstewart at nexicomgroup.net> wrote:

> Hi there...
> 
> I've never setup multicast routing before so here goes..;)  This is for
> an Occum device that requires IGMP for it's T1 interfaces for
> clocking....
> 
> Layout of devices:
> 
> Cisco 6509 (MSFC2)
> Local Occum equipment on VLAN2 (192.168.0.10)
> |
> |
> VLAN104 Lan Extension (10.1.1.1)
> |
> |
> Cisco 6503E (MSFC2) - switching only
> |
> |
> Cisco 2950 Switch - switching only
> |
> |
> Cisco 7206VXR Interface (10.1.1.2)
> |
> |
> Remote Occum equipment (172.16.10.10)
> 
> 
> The remote equipment 172.16.10.10 needs to talk to local equipment
> 192.168.0.10
> 
> The 6503E and 2950 "in the middle" are purely transporting the VLAN on
> layer2
> 
> Here's what I have setup so far:
> 
> Cisco 6509
> 
> ip multicast-routing
> 
> interface Vlan2
>  description Occum Voice/Management
>  ip address 192.168.0.10 255.255.255.128
>  ip access-group 104 out
>  ip pim dense-mode
> 
> interface Vlan104
>  description 100 Meg LAN
>  ip address 10.1.1.1 255.255.255.248
>  ip pim dense-mode
> 
> 

Using dense mode is generally considered Not a Good Thing.  It will flood,
then periodically prune,  multicast traffic out all interfaces, regardless
if there aren't any recipients interested in the traffic on an interface.

You should definitely use PIM Sparse mode, which will require configuring an
RP per group, as well as setting the interfaces to sparse mode.

> Cisco 7206VXR
> 
> ip multicast-routing
> 
> interface GigabitEthernet0/1
>  description 100 Meg
>  ip address 10.1.1.2 255.255.255.248
>  ip pim dense-mode
>  duplex full
>  speed 100
>  media-type rj45
>  no negotiation auto
>  no clns route-cache
> 
> interface GigabitEthernet0/3
>  description Occum Voice/Management
>  ip address 172.16.10.10 255.255.255.192
>  ip access-group 104 out
>  ip pim dense-mode
>  duplex full
>  speed 1000
>  media-type rj45
>  no negotiation auto
>  no clns route-cache
> 
> 
> 
> As I have said, I'm completely new to multicast/IGMP etc.... so any help
> would be appreciated... I've read some docs etc. but I'm sure something
> is missing in this equation....
> 
> I've been reading about Multicast Extensions to OSPF and we use OSPF
> everywhere in our networks pretty much including this link.... would
> this solve my problem?

Do you know what group number this device is using?  You will need to add
these groups to ACL 104 as well.

I've never used mOSPF, but I could swear reading that it isn't supported in
IOS.  You'll want to use PIM  (Protocol Independent Multicast), which relies
on the unicast routing table for RPF checks.  The "protocol independence"
comes from the fact that you can use RIP/OSPF/BGP/EIGRP/Whatever for your
unicast routing table.

You may want to provide the output of show ip mroute to get an idea of what
groups may be running at the moment.
> 
> Thanks, appreciate any responses ;)
> 
> Paul
> 
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