From: David Timmons (masterdt@yahoo.com)
Date: Tue Jul 25 2006 - 15:03:01 ART
I agree the mapping agent should resolve any conflicts when a RP-candidate is announced w/r to a group. I think the key with this is that you may have different RP's in an environment w/r to a group.The auto-RP feature offers redundancy over the BSR method. If an RP does not exist for a group, then dense mode will be used; the autorp listener command, when used with sparse mode interfaces, restricts dense mode flooding to 224.0.1.39 and 224.0.1.40. RP candidates will announce their existence on 224.0.1.39: ip pim send-rp-announce. All multicast routers listen on 224.0.1.40; hence, a mapping agent must be used to select the RP with the highest IP and advertise it to with the 224.0.1.40 group: ip pim send-rp-discovery. All RP filters must be performed on the mapping-agent.
In the original example, I don't see the ip pim send-rp-discovery command:assume it must be on another router. It is my understanding that all multicast routers listen to 224.0.1.40 to learn of the Auto-RP. So, in your example, you really have to look at the mapping agent. The deny in the ACL should impact what groups this RP candidate announces to the mapping agent; it does impact what the mapping agent tells the router is it's RP for a specific group. Just my thoughts, still trying to learn more about multicast.
dt
----- Original Message ----
From: Radoslav Vasilev <deckland@gmail.com>
To: Ivan <ivan@iip.net>
Cc: ccielab@groupstudy.com; Nick Davey <nicky.davey@gmail.com>
Sent: Tuesday, July 25, 2006 8:35:05 AM
Subject: Re: Multicast AutoRP
This is entirely incorrect statement.
Multiple C-RP may announce different group-ranges...
It is the Auto-RP mapping agent's duty to resolve conflicts and send the
result using the discovery multicast group.
Always help to test ;)
On 7/25/06, Ivan <ivan@iip.net> wrote:
>
> In AutoRP all mapping agents must announce the same information. In this
> case
> MA have not consistent information. I think to test this. Need have only
> one
> MA for all RP.
>
> Probably R4 get AutoRP-discovery from R1 after announce from itself. To
> see
> this situation more deeply need to debug all process RP-mapping.
>
> > Nick,
> >
> > When a negative group-range is received through Auto-RP, a group in the
> > range will be treated as dense mode group.
> > What's more important is that even if you had another RP advertising a
> > normal (positive) group-range, the negative one will override it across
> > your PIM domain.
> >
> > Here's my testing of the override process:
> >
> > R1 and R4 connected through a common ethernet segment:
> >
> > hostanme Rack1R1
> > ip multicast-routing
> >
> > interface Loopback0
> > ip address 150.1.1.1 255.255.255.0
> > no ip directed-broadcast
> > ip pim sparse-dense-mode
> > !
> > interface FastEthernet0/0
> > ip address 155.1.146.1 255.255.255.0
> > no ip directed-broadcast
> > ip pim sparse-dense-mode
> >
> > ip pim send-rp-announce Loopback0 scope 10 group-list 1
> > ip pim send-rp-discovery scope 10
> > !
> > access-list 1 deny 239.0.0.0 0.0.0.255
> > access-list 1 permit 224.0.0.0 7.255.255.255
> >
> >
> > hostname Rack1R4
> > ip multicast-routing
> >
> > interface Loopback0
> > ip address 150.1.4.4 255.255.255.0
> > ip pim sparse-dense-mode
> >
> > interface FastEthernet0/1
> > ip address 155.1.146.4 255.255.255.0
> > ip pim sparse-dense-mode
> > duplex auto
> > speed auto
> >
> > ip pim send-rp-announce Loopback0 scope 10 group-list 1
> > ip pim rp-candidate Loopback0 group-list 10 priority 1
> >
> > access-list 1 permit 239.0.0.0 0.0.0.255
> >
> >
> > As you see, Router1 announces 224/5 but also (negativelly) 239/8.
> > Router 4 announces 239/8 normally.
> >
> > Check R4's opinion on the group-to-rp mapping:
> > Rack1R4#sh ip pim rp mapping
> > PIM Group-to-RP Mappings
> > This system is an RP (Auto-RP)
> > This system is a candidate RP (v2)
> >
> > Group(s) 224.0.0.0/5
> > RP 150.1.1.1 (?), v2v1
> > Info source: 150.1.1.1 (?), elected via Auto-RP
> > Uptime: 00:04:45, expires: 00:02:11
> > Group(s) (-)239.0.0.0/24
> > RP 150.1.1.1 (?), v2v1
> > Info source: 150.1.1.1 (?), elected via Auto-RP
> > Uptime: 00:04:45, expires: 00:02:09
> > Rack1R4#
> >
> >
> > Although R4 announes 239/8 :
> >
> > Auto-RP(0): Build RP-Announce for 150.1.4.4, PIMv2/v1, ttl 10, ht 181
> > Auto-RP(0): Build announce entry for (239.0.0.0/24)
> > Auto-RP(0): Send RP-Announce packet on FastEthernet0/1
> >
> >
> > R1(the mapping agent) ignores and send the -239/8:
> >
> > Auto-RP(0): Build RP-Announce for 150.1.4.4, PIMv2/v1, ttl 10, ht 181
> > Auto-RP(0): Build announce entry for (239.0.0.0/24)
> > Auto-RP(0): Send RP-Announce packet on FastEthernet0/1
> >
> > On 7/25/06, Nick Davey <nicky.davey@gmail.com> wrote:
> > > Thanks Rado,
> > >
> > > So does that mean that this group does not have an RP ?
> > >
> > > Nick
> > >
> > > On 7/25/06, Radoslav Vasilev < deckland@gmail.com> wrote:
> > > > Hi Nick,
> > > >
> > > > What you've done is a negative announcement for the
> administrativelly
> > > > scoped range 239/8.
> > > > This happen when you have a deny statement in the standard ACL you
> use
> > > > on the RP.
> > > >
> > > > I think the "negative prefix" feauture for Auto-RP was addes
> somewhere
> > > > in 12.0
> > > >
> > > >
> > > > Cheers,
> > > > Rado
> > > >
> > > > On 7/25/06, Nick Davey < nicky.davey@gmail.com> wrote:
> > > > > Hi all,
> > > >
> > > > I configured autorp as follows:
> > > >
> > > > ip pim send-rp-announce Loopback0 scope 16 group-list MCast
> > > >
> > > > ip access-list standard MCast
> > > > deny 239.0.0.0 0.255.255.255
> > > > permit 232.0.0.0 7.255.255.255
> > > >
> > > >
> > > > When i do a show ip pim rp mapping i see the following
> > > >
> > > > Group(s) 232.0.0.0/5
> > > > RP 150.1.6.6 (?), v2v1
> > > > Info source: 150.1.6.6 (?), elected via Auto-RP
> > > > Uptime: 00:32:43, expires: 00:02:13
> > > > Group(s) (-)239.0.0.0/8
> > > > RP 150.1.6.6 (?), v2v1
> > > > Info source: 150.1.6.6 (?), elected via Auto-RP
> > > > Uptime: 00:32:43, expires: 00:02:16
> > > >
> > > >
> > > > Why is group 239.0.0.0 assigned an RP when it is denied in the ACL?
> > > >
> > > > And what does the (-) before 239.0.0.0/8 mean?
> > > >
> > > > Hope someone can answer this
> > > >
> > > > Regards,
> > > >
> > > > Nick
> > > >
> > > >
> _______________________________________________________________________
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>
> --
> Ivan
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