Re: VLans and Multicast/IP forward protocol [7:49115]
Comments inline: ""Priscilla Oppenheimer"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Steven A. Ridder wrote: > > > > I just want to make sure I'm correct: A VLAN will contain > > multicast traffic > > unless ip multicast routing is on the router (or other l3 > > device) right? > > Yes. VLANs contain multicasts just like they contain broadcasts. Or maybe > constrain is a better verb. Actually, bound may be the best verb. Is there any way a switch can "bleed" multicast traffic from one port to another, even though they are both tagged with different VLANS? I have a customer that when the do multicast traffic in one VLAN, all the lights light up on all the ports, like it would in a STP loop or something. I'm just trying to figure out how that could happen, when I know multicast is turned off. It's driving me nuts. > > > So > > a whole switch (or stack of switches) will not be flooded with > > one VLAN's > > multicast traffic, right? > > Right. > > > > > Also, why is "ip forward-protocol" or Ip helper-address on vlan > > interfaces > > on a l2 switch such as a cat 3500? Shouldn't that be on the > > subinterface of > > the l3 device? > > I agree that ip forward-protocol and ip helper-address only have meaning on > a L3 switch. But for a 3524, the command is there, and it's a L2 switch, so can I assume the IOS developers just didn't remove it? > > > > Priscilla Oppenheimer > http://www.priscilla.com > > > > > > -- > > RFC 1149 Compliant Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=49148&t=49115 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: VLans and Multicast/IP forward protocol [7:49115]
Steven A. Ridder wrote: > > I just want to make sure I'm correct: A VLAN will contain > multicast traffic > unless ip multicast routing is on the router (or other l3 > device) right? Yes. VLANs contain multicasts just like they contain broadcasts. Or maybe constrain is a better verb. Actually, bound may be the best verb. > So > a whole switch (or stack of switches) will not be flooded with > one VLAN's > multicast traffic, right? Right. > > Also, why is "ip forward-protocol" or Ip helper-address on vlan > interfaces > on a l2 switch such as a cat 3500? Shouldn't that be on the > subinterface of > the l3 device? I agree that ip forward-protocol and ip helper-address only have meaning on a L3 switch. Priscilla Oppenheimer http://www.priscilla.com > > -- > RFC 1149 Compliant > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=49142&t=49115 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: VLans and Multicast/IP forward protocol [7:49115]
Comments inline. Steven A. Ridder wrote: > I just want to make sure I'm correct: A VLAN will contain > multicast traffic > unless ip multicast routing is on the router (or other l3 > device) right? So > a whole switch (or stack of switches) will not be flooded with > one VLAN's > multicast traffic, right? I think it depends on the type of multicast, right? I don't recall specifically enabling multicast, but EIGRP still works. But I'm not sure about other multicast traffic. Most of the time, can't you set the TTL = 1 on your multicast source so that it won't cross L3 boundaries? > Also, why is "ip forward-protocol" or Ip helper-address on vlan > interfaces > on a l2 switch such as a cat 3500? Shouldn't that be on the > subinterface of the l3 device? Which model 3500? AFAIK, the 3550s have full L3 capabilites, so evey port could be an L3 device (this is just my understanding but I could be mistaken). The older 3524 and 3548, since they are just L2, I guess you could put IP Helper on the VLAN interface, but I can't think of why. That VLAN interface is only used for the switch (as an IP device) to communicate with the rest of the network, not that the VLAN interface is actually doing anything at L3 with any of the traffic coming in on the switchports. That's about the best I can figure =) Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=49119&t=49115 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
