From: Radoslav Vasilev (deckland@gmail.com)
Date: Tue Jul 25 2006 - 09:32:55 ART
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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