multicast

[rsys]

Hello,

I have a basic question on IP multicasting.

If I have a router (with two ethernet interfaces) connecting two internal networks (10.0.0.0/255.0.0.0 and 192.168.1.0/255.255.255.0), will the router allow multicast packets from one network to the other?.. I mean, is multicasting by default disabled on all routers?..

Also, the multicast IP range as I understand is entirely different from the above IP range?..So does this mean, there is no way I can have IP multicasting with the above setup?

Thanks a lot for your suggestions.

RM.

 

[gconnect]

although it is available on IP Plus and Enterprise IOS versions, it is disabled by default and you have to enable it with the global config command:


ip multicast-routing
ip multicast route-limit 10000 (or whatever limit you want)

then the interface config commands

int e0
ip pim dense-mode


this is especially useful in Netware 5 and 6 environments that advertise services via SLP (UDP) over IP instead of SAP and IPX.

 

[gconnect]

sorry i forgot to answer the 2nd part of your question


"Also, the multicast IP range as I understand is entirely different from the above IP range?..So does this mean, there is no way I can have IP multicasting with the above setup?"

actually as far as communicating outside of your LAN and the IP range of mcast addresses, in most instances it is up to the application that you are using



EXAMPLE
for instance with netware 5 and 6 using pure TCP-IP environment

the netware client for windows uses the multicast addresses of 239.0.0.45 (i think it's 45) to look for services (if you do not statically configure the directory server in the client app's properties). The servers also respond to that mcast address.


so say you have no netware server on your LAN but there is one on a remote LAN (in your domain), there are also printers and other file servers on that LAN you need access to. for completeness your IP address on your pc is 10.1.1.3

1
you boot up your client pc


2
the client application (netware client) sends Service Locator Request packets to 239.0.0.45

3
you type in your username and password credentials

4
the router forwards those packets out any interface that has mcast routing enabled (LAN and WAN)

5
the peer remote router with the Netware Server accepts these pkts and forwards them out all interfaces with mcast enabled (LAN and WAN)

6
the netware server 10.1.2.10 responds with the IP addresses of it's resources including the directory logon server (itself)

7
so now the client logs onto the network using Multicast AutoDiscovery and knows where all of the other network services are

it usually doesn't matter what the client's IP address (bound to the NIC) is, applications handle most of the discovery of services. forwarding of mcast pkts must be enabled on the router interfaces that have (LAN) or need access to (WAN) devices running the multicast-based applications



Get Connected - I.T.

 

[rsys]

Thanks a lot for your reply. That does clear up things.