Sorry I still do not get it, this is not an added capability from IOS, this is stated in RFC. In your early email, you questioned:
>>>With IGMP version 2 it > > > seems you do not need it. But what happen then if you have both IGMP v2 > > and > > > PIM DR's ?? Do they both query the hosts ? I am not sure what the question means, the interface either runs IGMP v2 or v1, if it is running v1, the DR selected by the PIM sends IGMP query messages. If it is running v 2, the lower ip is the querier, in v 2 it does not matter who the DR is. It is also a bit confusing the way Routing TCP/IP Volume II describes DR ( I have not checked with the book, just based on your quote), it first says PIM-DM does not need a DR, this is right, but it also says: " This is the role of the PIM-DM (and PIM-SM) designated router ", IMHO, this is not very accurate, the role of DR in DM is for IGMP v1 but in SM, as you mentioned in your yesteardy's email is mainly responsible for forwarding the join/prune messages to the RP, of course, it is also useful for IGMP, if v1 is running. Kent ----- Original Message ----- From: "richard dumoulin" To: "Kent Yu" ; Sent: Friday, August 16, 2002 2:10 PM Subject: Re: Multicast DR and IGMP querier [7:51458] > Ok, > > " PIM-DM elects a designated router on multiaccess networks. The protocol > itself does not need a DR, but recall that IGMPv1 does not have a querier > process and relies on the routing protocol to elect a DR to manage IGMP > queries. This is the role of the PIM-DM (and PIM-SM) designated router " > > Chapter 5 page 484 of Routing TCP/IP Volume II > > > Regards. > > Note: Scott is right, Multicast is wonderfully explained in this book. I > just have to find time to read all that books ;)) > ----- Original Message ----- > From: "Kent Yu" > To: "richard dumoulin" ; > Sent: Friday, August 16, 2002 7:06 PM > Subject: Re: Multicast DR and IGMP querier [7:51458] > > > > If that's the case, I am confused too, could you show us the link from > cisco > > explaining this > > added capability you mentioned? From reading your email, I am not even > clear > > what this added capability it is about. > > > > > > Thanks > > Kent > > > > ----- Original Message ----- > > From: "richard dumoulin" > > To: > > Sent: Friday, August 16, 2002 11:29 AM > > Subject: Re: Multicast DR and IGMP querier [7:51458] > > > > > > > Here it is !! That was my confusion, because it seems that this > > capability > > > was added in order to query IGMP version 1 hosts. With IGMP version 2 it > > > seems you do not need it. But what happen then if you have both IGMP v2 > > and > > > PIM DR's ?? Do they both query the hosts ? > > > > > > Any Multicast expert right there ? > > > > > > Regards. > > > ----- Original Message ----- > > > From: "Kent Yu" > > > To: "richard dumoulin" ; > > > Sent: Friday, August 16, 2002 4:42 PM > > > Subject: Re: Multicast DR and IGMP querier [7:51458] > > > > > > > > > > Do you mean that in IOS if a router is running PIM and is a DR, it > will > > > > query even if it sees IGMP query messages from another router with > lower > > > ip > > > > address? > > > > > > > > Kent > > > > > > > > ----- Original Message ----- > > > > From: "richard dumoulin" > > > > To: "Kent Yu" ; > > > > Sent: Friday, August 16, 2002 10:34 AM > > > > Subject: Re: Multicast DR and IGMP querier [7:51458] > > > > > > > > > > > > > RFC's are great, but have to look also at how Cisco IOS implements > the > > > > rfc. > > > > > PIM DR's use IGMP to query the hosts too !! > > > > > > > > > > Regards. > > > > > ----- Original Message ----- > > > > > From: "Kent Yu" > > > > > To: "richard dumoulin" ; > > > > > Sent: Friday, August 16, 2002 4:20 PM > > > > > Subject: Re: Multicast DR and IGMP querier [7:51458] > > > > > > > > > > > > > > > > Richard, > > > > > > > > > > > > As we mentioned yesterday, only routers speak PIM, I am not sure > > where > > > > you > > > > > > got the impression that PIM DRs query the hosts, routers only use > > IGMP > > > > to > > > > > > query the hosts. > > > > > > > > > > > > I think as many have suggested, nothing is better than reading the > > > > specs, > > > > > in > > > > > > this case, RFC 2117 should explain this pretty well. > > > > > > > > > > > > HTH > > > > > > Kent > > > > > > > > > > > > ----- Original Message ----- > > > > > > From: "richard dumoulin" > > > > > > To: > > > > > > Sent: Friday, August 16, 2002 3:47 AM > > > > > > Subject: Re: Multicast DR and IGMP querier [7:51458] > > > > > > > > > > > > > > > > > > > Raj Santiago wrote: > > > > > > > > > > > > > > > > Hi Richard, > > > > > > > > > > > > > > > > > > > > > > > > Okay your question is basically what is a "IGMP querier and > > > > > > > > Multicast Designated Router" > > > > > > > > > > > > > > > > > > > > > > > > Igmp querier is the router in charge to see if any hosts want > > > > > > > > to listen to a multicast stream. > > > > > > > > > > > > > > > > Designated Router is the router is charge to facilitate pim > > > > > > > > join, prune and register messages(This also depends on the > > > > > > > > mode of pim your running, im being very abstract here); > > > > > > > > Basically the multicast routing part. > > > > > > > > > > > > > > But it seems to me that the DR will also query the hosts!! > > > > > > > > > > > > > > > > > > > > > > > > Under IGMP version 1, the router with the highest ip address > > > > > > > > was BOTH the IGMP querier and Designated Router. > > > > > > > > > > > > > > > > Under IGMP version 2, the router with highest ip address is > the > > > > > > > > DR and the router with the lowest ip address is the IGMP > > querier. > > > > > > > > > > > > > > If I am right, both the DR and the querier will query the hosts > ?? > > > > > > > > > > > > > > > > > > > > > Cheers. > > > [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=51538&t=51458 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
