[c-nsp] multicast on layer 2

[Andrew K Ho]

Yes, I'm aware of the fact that every frame will be broadcast, but our 
"planners" have "decided" it should be "that way."  I better stop there or 
else everything I say will be in quotes :)  I'll pursue the PIM route but 
as far as I was guessing, the server would have taken care of that, 
otherwise, how would it work without a router interface or on a purely 
layer 2 setup--i.e. using a hub only?

Thx again.

Andy



"Tantsura, Jeff" <jtantsura at ugceurope.com> 
06/27/2005 10:14 AM

To
"'Andrew K Ho'" <aho at yorku.ca>, Tim Stevenson <tstevens at cisco.com>
cc
cisco-nsp at puck.nether.net
Subject
RE: [c-nsp] multicast on layer 2






Presence of layer 3 interface on the same VLAN could change the picture.
Since sources and receivers would register on it enabling PIM could help.
Could you test it with PIM enabled and let me know whether it helped?

BTW without IGMP snooping there's no point in using multicast, in fact
switch will broadcast every multicast frame.

--
Jeff Tantsura  CCIE# 11416
Senior IP Network Engineer


-----Original Message-----
From: Andrew K Ho [mailto:aho at yorku.ca] 
Sent: 27 June 2005 15:28
To: Tim Stevenson
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] multicast on layer 2

I'm afraid this setup is just on layer 2.  Two directly connected switches 

on trunk links, both allowing the same vlan.  Although there is a vlan 
interface on the router, the traffic shouldn't be processed by the router. 

 Hence no need for PIM (as Jeff pointed out).  For reasons I can't fathom, 

IGMP snooping is always off on our network, and as our planners want it to 

remain this way, the IGMP querier feature would not make any difference.

Thx for all the replies.

Andy



Tim Stevenson <tstevens at cisco.com> 
06/24/2005 03:57 PM

To
Andrew K Ho <aho at yorku.ca>, cisco-nsp at puck.nether.net
cc

Subject
Re: [c-nsp] multicast on layer 2






You might try:
* enabling PIM on an SVI in that VLAN
* enabling the IGMP querier feature
* disabling IGMP snooping (not really advisable, floods to all ports)

For IGMP snooping to work properly, an IGMP querier MUST be present in the 


VLAN.

See:
http://www.cisco.com/warp/public/473/38.html

HTH,
Tim

At 12:28 PM 6/24/2005, Andrew K Ho declared:
>Hi, I was hoping someone could help me on this.
>
>I'm having a problem with an application on our network called Drive 
Image
>Pro (used to push pc images to build client machines), which purports to
>be a multicast application, but which is only being used at layer 2 as 
all
>traffic btn server and client  is contained in 1 vlan, hence is working
>essentially the same as broadcasts.  Howevever, the server and client 
send
>multicast packets to a multicast address to send packets.
>
>The server is connected to  Model / Serial cisco WS-C6509  OS / Version
>ios / 12.1(22)E2 on a 100m connection and the client is connected to a
>100m port on  Model / Serial cisco 4506  OS / Version ios / 12.2(20)EW .
>They are connected directly through a trunk link, running at gig on 
fiber.
>  The server and  client are pingable from either side so there is no
>reachability issue.
>
>If the server and client are both on the 4506, it works fine, but won't
>work if connected as described above.  There are no configs affecting
>multicast packets.
>
>Has anyone come across a problem like this or have any clue as to why it
>may not be working?
>
>Thx in advance
>
>Andy
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Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Technical Marketing Engineer, Catalyst 6500
Cisco Systems, http://www.cisco.com
IP Phone: 408-526-6759
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