Re: Auto RP with sparse-mode and no dm-fallback..and its

Hi Mohamed
This info is partly based on my tests, so ppl feel free to disagree:

Any routers directly connected to a mapping agent that are PIM neighbors of
the mapping agent will receive the rp discovery messages regardless of pim
mode.
This is because the mapping agent floods the RP to group mapping out all pim
enabled interfaces (even out loopback ints).
As a result, directly connected routers will receive the group to rp
mapping.
However the directly connected routers will not send rp discovery messages
to any downstream routers unless:

The directly connected router has a downstream interface running
sparse-dense or dense mode
or
The directly connected router is running ip pim autorp listener

This explains why in your scenario, R2, which is directly connected to your
mapping agent, receives the rp discovery messages.
If you connect a downstream router off R2, and only run pim sparse mode on
the interface to the downstream router and keep ip pim autorp listener
disabled, you should observe the same behaviour outlined above.

Regards
Roy

The key is whether the router that is directly connected to the mapping
agent chooses to take any action based

2009/8/27 Mohamed El Henawy <m.henawy_at_link.net>

> so why we use BSR ...i thought we used it when we couldn't use Auto RP (
> no sparse dense mode )
>
>
>
> ----- Original Message -----
> *From:* Roy Waterman <roy.waterman_at_gmail.com>
> *To:* Mohamed El Henawy <m.henawy_at_link.net>
> *Cc:* Mark Matters <markccie_at_gmail.com> ; Keegan.Holley_at_sungard.com ; G2<farawayguy_at_gmail.com>; Cisco
> certification <ccielab_at_groupstudy.com> ; nobody_at_groupstudy.com
> *Sent:* Thursday, August 27, 2009 1:00 PM
> *Subject:* Re: Auto RP with sparse-mode and no dm-fallback..and its
> working
>
> Hi Mohamed
>
> Regarding your point:
>
> -------------
> Without any pings from R2 to this group there is maping ...Auto RP sent
> > the update via maping agent R0 to R2
> -------------
>
> Pinging a multicast group has no relevance to RP announce or discovery
> messages.
> R2 is automatically listening to group 224.0.1.40 when PIM was enabled on
> an interface.
> As R0 sends RP discovery messages to 224.0.1.40, R2 learns of the group to
> rp mappings.
>
>
> 2009/8/27 Mohamed El Henawy <m.henawy_at_link.net>
>
>> Hello Roy ,
>>
>> yes i configured both to use the loopback 10.10.10.10
>>
>>
>> here is the config
>>
>> > R1-----LAN-----R0-----FR------R2
>> > R1
>> > FastEthernet0/0 1.1.1.1 YES manual up up
>> > !
>> > interface FastEthernet0/0
>> > ip address 1.1.1.1 255.255.255.0
>> > ip pim sparse-mode
>> > ip igmp join-group 224.11.11.11
>> > duplex auto
>> > speed auto
>> >
>> > R0
>> > !
>> > interface FastEthernet0/0
>> > ip address 1.1.1.2 255.255.255.0
>> > ip pim sparse-mode
>> >
>> > end
>> >
>> > R0#sh run int s1/0
>> > ip address 2.2.2.1 255.255.255.0
>> > ip pim sparse-mode
>> > encapsulation frame-relay
>> > serial restart-delay 0
>> > frame-relay map ip 2.2.2.2 101 broadcast
>> > end
>> >
>> > R0#
>> >
>> > interface Loopback0
>> > ip address 10.10.10.10 255.255.255.0
>> > ip pim sparse-mode
>> > end
>> >
>> > ip pim send-rp-announce Loopback0 scope 10 group-list 10
>> > ip pim send-rp-discovery Loopback0 scope 10
>> >
>> > R0#sh access-lists 10
>> > Standard IP access list 10
>> > 10 permit 224.11.11.11
>> > R0#
>> >
>> > R2#
>> > !
>> > interface Serial1/0
>> > ip address 2.2.2.2 255.255.255.0
>> > ip pim sparse-mode
>> > encapsulation frame-relay
>> > serial restart-delay 0
>> > frame-relay map ip 2.2.2.1 202 broadcast
>> >
>> > ip route 10.10.10.10 255.255.255.255 2.2.2.1
>> >
>> >
>> > before this route was aded i get
>> >
>> > *Mar 1 00:16:39.427: IP(0): s=10.10.10.10 (Serial1/0) d=224.0.1.40
>> > id=166, ttl=9, prot=17, len=52(48), RPF lookup failed for source
>> >
>> >
>> >
>> > then i correct it and after that i noticed this debug on R2
>> >
>> > RP 10.10.10.10
>> > *Mar 1 00:19:35.375: MRT(0): Update (*,224.0.1.40), RPF /0.0.0.0
>> > *Mar 1 00:19:35.375: MRT(0): Update Serial1/0/224.0.1.40 in the olist
>> of
>> > (*, 224.0.1.40), Forward state - MAC built
>> > *Mar 1 00:19:37.051: MRT(0): Update (*,224.0.1.39), RPF /0.0.0.0
>> > *Mar 1 00:19:37.051: MRT(0): Update Serial1/0/224.0.1.39 in the olist
>> of
>> > (*, 224.0.1.39), Forward state - MAC not built
>> > *Mar 1 00:19:38.527: IP(0): s=10.10.10.10 (Serial1/0) d=224.0.1.40
>> > id=229, ttl=9, prot=17, len=52(48), mroute olist null
>> > *Mar 1 00:19:38.531: Auto-RP(0): Received RP-discovery, from
>> 10.10.10.10,
>> > RP_cnt 1, ht 181
>> > *Mar 1 00:19:38.531: Auto-RP(0): Update (224.11.11.11/32,
>> > RP:10.10.10.10), PIMv2 v1(?), v2v1 ===========================>
>> > Info source: 10.10.10.10 (?), elected via Auto-RP
>> > Uptime: 00:00:54, expires: 00:02:02
>> > R2#
>> >
>> > R2#sh ip pim rp map
>> > PIM Group-to-RP Mappings
>> >
>> > Group(s) 224.11.11.11/32
>> > RP 10.10.10.10
>> >
>> > Without any pings from R2 to this group there is maping ...Auto RP sent
>>
>> > the update via maping agent R0 to R2
>> >
>> >
>> >
>>
>> ----- Original Message -----
>> *From:* Roy Waterman <roy.waterman_at_gmail.com>
>> *To:* Mohamed El Henawy <m.henawy_at_link.net>
>> *Cc:* Mark Matters <markccie_at_gmail.com> ; Keegan.Holley_at_sungard.com ; G2<farawayguy_at_gmail.com>; Cisco
>> certification <ccielab_at_groupstudy.com> ; nobody_at_groupstudy.com
>> *Sent:* Thursday, August 27, 2009 12:50 AM
>> *Subject:* Re: Auto RP with sparse-mode and no dm-fallback..and its
>> working
>>
>> Hi Mohammed
>>
>> Looks like RP = mapping agent = 10.
>>
>> *Mar 1 00:36:16.159: Auto-RP(0): Received RP-discovery, from *
>> 10.10.10.10*, <-- received from mapping agent
>> RP_cnt 1, ht 181
>>
>> Have you configured both ip pim send rp announce & send rp discovery on
>> 10.10.10.10?
>> You should expect to see the mappings on your routers as they start
>> automatically listening to 224.0.1.40 as soon as u configured pim...
>>
>> As Keegan mentioned, please post the configs...
>>
>> Regards
>> Roy
>>
>> 2009/8/26 Mohamed El Henawy <m.henawy_at_link.net>
>>
>>> What i dont understand is how come we are enabling only sparse and yet we
>>> can
>>> see the maping on all the routers...why use BSR then
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>> ------------------------------
>>
>>
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>> 12:16:00
>>
>>
>
>
> --
> Regards
> Roy
>
> ------------------------------
>
>
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> Checked by AVG - www.avg.com
> Version: 8.5.409 / Virus Database: 270.13.69/2328 - Release Date: 08/26/09
> 12:16:00
>
>

-- 
Regards
Roy
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