Re: PIM DR vs IGMP Querier

Hi Jorge,

DR is a PIM function relevant to SM, used to elect a router on a multi
access network responsible for sending register
/prune messages toward the RP
Election based on
1)Highest Priority
2)Highest IP address

IGMP Querying Router is the router on a multi access network that is
responsible for sending IGMP host queries
Election:
The router with the lowest IP address is elected

PIM Assert:on a multi access network where two or more routers exist the
decision on who will forward the multicast packets on the segment is based
on the election of a forwarder:
-Admin Distance of the routers to the group source (lowest wins)
-Routing Protocol metric to the group source (lowest wins)
-Router with the highest IP address wins.

Hope this helps!

Best Regards,

On Mon, Jun 14, 2010 at 7:08 PM, Jorge Cortes
<jorge.cortes.cano_at_gmail.com>wrote:

> Hi,
>
> Thank you all for looking at this.
>
> This is getting more confusing, so let's try to clear things up.
>
> When the senders are on a shared media and there is more than one multicast
> capable router on the segment, the router that will register the source or
> sources with the RP is the DR, which, by default is the router with the
> highest IP address on the segment. There is no Assert procedure on the
> segment where there are only senders located. Assert only takes place for
> shared segments where there are receivers located -note there can be
> senders
> as well.
>
> Now, the confusion arises on shared segments where there are receivers. In
> a
> previous mail you said:
>
> "The one who receive IGMP messeges and send the join message towards RP
> (signalling) is always the same router. "
>
> Hosts signal IGMP messages asynchronously, and all multicast capable
> routers
> on the segment process these messages and respond to these messages at the
> beginning, thus IGMP Querier election process needs to take place as well
> as
> PIM DR election process. However both election processes use different
> criteria. IGMP Querier uses lowest IP address and PIM DR uses highest IP
> address, this is why without any parameter modification (i.e. altering
> priorities) the PIM DR and the IGMP Querier cannot be the same router.
>
> Now, back to my original doubt, is it true that both the PIM DR and IGMP
> Querier help receivers build RPT trees towards the RP? Or is it just the
> PIM
> DR who can do this?
> If both PIM DR and IGMP Querier can signal RPT Trees towards the RP and
> these two are different routers, how is this ultimately handled? Will
> multicast traffic from sources be initially sent to both the PIM DR and
> IGMP
> Querier? Then both routers will forward this multicast traffic on to the
> shared segment forcing assert procedure to take place and finally the
> assert
> loser will prune its LAN interface from the OIL?
>
> Is this the correct order of operations?
>
>
> Thanks!
> Jorge
>
> On Sun, Jun 13, 2010 at 10:25 AM, <kebramccie_at_gmail.com> wrote:
>
> > Outgoing interface list and incoming interface list I guess
> > Sent from my BlackBerry wireless device from MTN
> >
> > -----Original Message-----
> > From: F H <sol3a1_at_gmail.com>
> > Sender: nobody_at_groupstudy.com
> > Date: Sun, 13 Jun 2010 10:57:44
> > To: Cisco certification<ccielab_at_groupstudy.com>
> > Reply-To: F H <sol3a1_at_gmail.com>
> > Subject: Re: PIM DR vs IGMP Querier
> >
> > Please forgive my ignorance, but what are the terms IIL and OIL?
> >
> >
> > Thanks
> >
> > On Sun, Jun 13, 2010 at 10:21 AM, masroor ali <masror.ali_at_gmail.com>
> > wrote:
> >
> > > As per my understanding about these terms, DR is the one who signals
> > > towards
> > > to RP so that RPT build (R2), and the assert forwarder would be R4 or
> R5.
> > > because the traffic is moving from sender--->
> R4/R5--->RP---->R2---->G1,
> > > and
> > > the router who unicast the multicast traffic to RP is the assert
> > forworder
> > > (if AD is low,metric is low,or higest IP address in that segment),
> > >
> > > On Sun, Jun 13, 2010 at 6:47 PM, Muzammil Malick <malickmuz_at_gmail.com
> > > >wrote:
> > >
> > > > Masroor.
> > > >
> > > > Would you also agree that R1 and R2 also send PIM Assert messages to
> > each
> > > > other to decide who is the Designated Forwarder TO the receiver?
> > > >
> > > >
> > > > On 12 June 2010 12:32, masroor ali <masror.ali_at_gmail.com> wrote:
> > > >
> > > >> Hi,
> > > >>
> > > >> G1(receiver)(Multicast group)
> > > >> |
> > > >> |
> > > >> ---------------------------------
> > > >> | |
> > > >> |(192.168.1.1) | f0/0 (OIL)
> > > >> R1 R2 (192.168.1.2)
> > > >> | | f0/1 (IIL)
> > > >> --------------------------------
> > > >> |
> > > >> |
> > > >> R3 (RP)
> > > >> |
> > > >> |
> > > >> ---------------------------------
> > > >> | |
> > > >> | |
> > > >> R4 R5
> > > >> | |
> > > >> --------------------------------
> > > >> |
> > > >> |
> > > >> source(S1)(sender)
> > > >>
> > > >>
> > > >> lets assume G1 is the IGMP group, who wants to receive the multicast
> > > >> traffic. G1 1st send the IGMP host membership to join the
> group(which
> > is
> > > >> also called signaling).As there are multiple routers R1, R2 in the
> > > >> segment,
> > > >> DR election process occur, the heighest IP address router (R2) wins
> > and
> > > >> create OIL(f0/0) . the DR (R2) send a join messege to RP, RP recieve
> > the
> > > >> jon
> > > >> messege, in this way RPT occur.
> > > >> note that untill the multicast reciver G1 signal nothing would
> happen.
> > > >>
> > > >> This is one part of the story. ((G1) IGMP reciever ---------> RP)
> > > >>
> > > >> The second part remains to discuss. ((S1)source------------> RP)
> > > >>
> > > >> The first hop route (R4, R5) encapsulate the multicast traffic into
> > > >> register
> > > >> message and unicast to RP, here two routers are the first-hop
> routers,
> > > now
> > > >> the PIM-assert come into play and now 1st check the AD, then metric,
> > > then
> > > >> heighest router IP become the forwarder and unicast the encapsulated
> > > >> multicast traffic into the register message to RP. then RP
> > > de-encapsulate
> > > >> the register message and forward to reciever.
> > > >>
> > > >> note: The 1st hop router keep on encapsulating the packet unless the
> > RP
> > > >> send
> > > >> a register-stop message.
> > > >>
> > > >>
> > > >>
> > > >> On Thu, Jun 10, 2010 at 10:33 PM, Jorge Cortes
> > > >> <jorge.cortes.cano_at_gmail.com>wrote:
> > > >>
> > > >> > I apologize I hit send button before finishing with the email.
> > > >> >
> > > >> > Although both protocols are used for different purposes, it is my
> > > >> > understanding that both, PIM DR and IGMP Querier, can signal SPT
> > > Trees
> > > >> > on behalf of the multicast receivers on a shared medium when PIM
> SM
> > > >> > is in use. Is this
> > > >> > correct?
> > > >> >
> > > >> > If this is correct, the following question arises. Lets assume
> the
> > > >> > following scenario
> > > >> >
> > > >> >
> > > >> >
> > > >> > ------------------------------
> > > >> > | |
> > > >> > R1 R2
> > > >> > \ /
> > > >> > \ /
> > > >> > \ /
> > > >> > \ /
> > > >> > \ /
> > > >> > \ /
> > > >> > RP
> > > >> >
> > > >> > If all IGMP and PIM parameters are left to the default, one of
> this
> > > >> > routers will become the IGMP Querier, lets say R1, and the other
> one
> > > >> > will become the PIM DR, lets say R2, so both will signal the SPT
> > Trees
> > > >> > for the groups on the shared segment. Since both routers signaled
> > the
> > > >> > SPT Tree, then both routers will forward the same multicast data
> on
> > > >> > the segment and the assert procedure will take place. Assuming R2
> > has
> > > >> > a better metric to the source it will become the assert winner and
> > R1
> > > >> > will prune its LAN interface from the OIL.
> > > >> >
> > > >> > Is this understanding correct?
> > > >> > Am I missing anything here?
> > > >> >
> > > >> > I appreciate your inputs.
> > > >> >
> > > >> > Thanks,
> > > >> > Jorge
> > > >> >
> > > >> >
> > > >> > Blogs and organic groups at http://www.ccie.net
> > > >> >
> > > >> >
> > > _______________________________________________________________________
> > > >> > Subscription information may be found at:
> > > >> > http://www.groupstudy.com/list/CCIELab.html
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >>
> > > >>
> > > >> --
> > > >> Regards,
> > > >> Masroor Ali
> > > >>
> > > >>
> > > >> Blogs and organic groups at http://www.ccie.net
> > > >>
> > > >>
> > _______________________________________________________________________
> > > >> Subscription information may be found at:
> > > >> http://www.groupstudy.com/list/CCIELab.html
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >
> > >
> > >
> > > --
> > > Regards,
> > > Masroor Ali
> > >
> > >
> > > Blogs and organic groups at http://www.ccie.net
> > >
> > > _______________________________________________________________________
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> >
> >
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> >
> > _______________________________________________________________________
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> >
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>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
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-- 
KJ
Blogs and organic groups at http://www.ccie.net