From: lhall@setnine.com
Date: Fri Mar 21 2008 - 01:03:15 ART
> This is always the case;
Actually its not, if it was I wouldn't have asked the question.
Heres an example to demonstrate:
R6#sh ip multicast
Multicast Routing: disabled
Multicast Multipath: disabled
Multicast Route limit: No limit
Multicast Triggered RPF check: enabled
Multicast Fallback group mode: Dense
R6#sh ip pim interface
Address Interface Ver/ Nbr Query DR DR
Mode Count Intvl Prior
R6#sh run int e1/1
interface Ethernet1/1
ip address 150.1.56.6 255.255.255.0
ip igmp join-group 230.5.5.5
half-duplex
end
R5#ping 230.5.5.5
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 230.5.5.5, timeout is 2 seconds:
Reply to request 0 from 150.1.56.6, 8 ms
Got a reply with no pim or multicast routing running on R6, this is not
possible to do on a 3750/3560.
> Isn't responding to your pings multicast routing????
No its not, running a protocol stack is not the same as routing. In this
case its acting as a host joining a group so multicast routing isn't
necessary.
> Doesn't processing the group with the join-group command require igmp be
> running (and how do we enable igmp??? By turning on pim!!!)
The router/switch that runs the join-group command does not 'process the
group'. Hosts or those devices acting as hosts do not enable igmp by
turning on pim, I'm not sure where you got that from...
Routers with the join-group command act as expected, these switches 3750's
and 3560's do not.
> -joe
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> lhall@setnine.com
> Sent: Thursday, March 20, 2008 7:00 PM
> To: ccielab@groupstudy.com
> Subject: ip igmp join-group 3750
>
> I'm doing some labs using 3750's, for a reason I cannot figure out,
> these will not respond to pings if on physical port (no switchport)
> you configure `ip igmp join-group X` _unless_ you also enable PIM on the
> on the interface and enable `ip multicast-routing distributed`.
> Does anyone know why this is?
>
> Wont work:
>
> interface FastEthernet1/0/3
> no switchport
> ip address 12.2.40.5 255.255.255.0
> ip igmp join-group 225.1.1.1
> no ip mroute-cache
>
> Will work:
>
> ip multicast-routing distributed
> !
> interface FastEthernet1/0/3
> no switchport
> ip pim dense-mode (or sparse etc)
> ip address 12.2.40.5 255.255.255.0
> ip igmp join-group 225.1.1.1
> no ip mroute-cache
>
> They are all WS-C3750-24TS running 12.2(25)SEE C3750-ADVIPSERVICESK.
>
>
> Luca
>
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