Re: More Multicast Understanding

Interesting, can you send me your configs and .net file? I am using
12.4(25a). I think you tried sending it before but I didn't get it. Thanks.

On Fri, Oct 16, 2009 at 1:01 PM, karim jamali <karim.jamali_at_gmail.com>wrote:

> Bryan,
>
> Thanx again for your support. I have labbed your scenario:
> R1----LAN1----R2/R3----LAN2----R4
>
> Just to confirm things R1 is the streamer and the RP. R2 has a preferred
> path to the the loopback of R1(source of the stream).
>
> R2#show ip route ospf
> 1.0.0.0/32 is subnetted, 1 subnets
> O 1.1.1.1 [110/3] via 123.0.0.1, 00:12:01, Ethernet0/0
>
> R3#show ip route ospf
> 1.0.0.0/32 is subnetted, 1 subnets
> O 1.1.1.1 [110/11] via 123.0.0.1, 00:09:58, Ethernet0/0
>
> R3 is the designated router on both subnets (R1,R2,R3) and (R2,R3) wich has
> the client of R4.
>
> R3#SHOW IP pim interface
> Address Interface Ver/ Nbr Query DR DR
> Mode Count Intvl Prior
> 123.0.0.3 Ethernet0/0 v2/S 2 30 1
> 123.0.0.3
> 23.0.0.3 Ethernet0/1 v2/S 1 30 1
> 23.0.0.3
>
> R2:
> *Mar 1 00:28:34.879: IP(0): s=1.1.1.1 (Ethernet0/0) d=239.1.1.1 id=176,
> ttl=253
> , prot=1, len=114(100), mroute olist null
> R3:
> *Mar 1 00:27:06.951: IP(0): s=1.1.1.1 (Ethernet0/0) d=239.1.1.1
> (Ethernet0/1) i
> d=173, ttl=253, prot=1, len=100(100), mforward
>
> ON R3:
> 1.1.1.1, 239.1.1.1), 00:00:12/00:02:50, flags: JT
> Incoming interface: Ethernet0/0, RPF nbr 123.0.0.1
> Outgoing interface list:
> Ethernet0/1, Forward/Sparse, 00:00:12/00:02:47
>
> This shows that in my scenario R3 is the one forwarding the traffic to the
> segment.
>
> Note that when on R2 I issued the command ip pim dr-priority 255. The
> behavior was reversed what I mean is:
> R2 is forwarding now:
> *Mar 1 00:34:08.707: IP(0): s=1.1.1.1 (Ethernet0/0) d=239.1.1.1
> (Ethernet0/1) i
> d=189, ttl=253, prot=1, len=100(100), mforward
> (1.1.1.1, 239.1.1.1), 00:01:33/00:02:00, flags: JT
> Incoming interface: Ethernet0/0, RPF nbr 123.0.0.1
> Outgoing interface list:
> Ethernet0/1, Forward/Sparse, 00:01:33/00:02:55, A
>
> R3 is not forwarding traffic anymore:
> *Mar 1 00:32:46.871: IP(0): s=1.1.1.1 (Ethernet0/0) d=239.1.1.1 id=192,
> ttl=253
> , prot=1, len=114(100), mroute olist null
> (1.1.1.1, 239.1.1.1), 00:04:20/00:00:43, flags: PJT
> Incoming interface: Ethernet0/0, RPF nbr 123.0.0.1
> Outgoing interface list: Null
>
> This is the model of the router as well as the image.
>
> Note that I am doing my simulation using dynamips.
>
> (C3640-JS-M), Version 12.4(17)
>
> Best Regards,
>
>
> On Fri, Oct 16, 2009 at 5:27 PM, Bryan Bartik <bbartik_at_ipexpert.com>wrote:
>
>> Karim,
>>
>> What IOS are you using? Look at my example and tell me if this is not what
>> you see.
>>
>> R1----LAN1----R2/R3----LAN2----R4
>>
>> R1 is RP and sender, sending from loopback at 1.1.1.1
>> R2's route metric is 3, R3's is 72 (manually manipulated cost)
>>
>> R2#sho ip route 1.1.1.1
>> Routing entry for 1.1.1.1/32
>> Known via "ospf 1", distance 110, metric 3, type intra area
>> Last update from 192.168.234.3 on FastEthernet1/0, 00:00:39 ago
>> Routing Descriptor Blocks:
>> * 192.168.234.3, from 1.1.1.1, 00:00:39 ago, via FastEthernet1/0
>> Route metric is 3, traffic share count is 1
>>
>> R3#sho ip rou 1.1.1.1
>> Routing entry for 1.1.1.1/32
>> Known via "ospf 1", distance 110, metric 72, type intra area
>> Last update from 192.168.234.2 on FastEthernet1/0, 00:00:01 ago
>> Routing Descriptor Blocks:
>> * 192.168.234.2, from 1.1.1.1, 00:00:01 ago, via FastEthernet1/0
>> Route metric is 72, traffic share count is 1
>>
>> Now on LAN2 connected to R4, R3 is the DR:
>>
>> R3#sho ip pim interface
>> Address Interface Ver/ Nbr Query DR DR
>> Mode Count Intvl Prior
>> 192.168.123.3 FastEthernet0/0 v2/S 2 30 1
>> 192.168.123.3
>> 192.168.234.3 FastEthernet1/0 v2/S 2 30 400
>> 192.168.234.3
>>
>> R2#sho ip pim int
>> Address Interface Ver/ Nbr Query DR DR
>> Mode Count Intvl Prior
>> 192.168.123.2 FastEthernet0/0 v2/S 2 30 1
>> 192.168.123.3
>> 192.168.234.2 FastEthernet1/0 v2/S 2 30 200
>> 192.168.234.3
>> R2#
>>
>> R4 has joined 239.1.1.1. When R1 sends traffic to 239.1.1.1, R2 is
>> forwarding it. We verify by looking at the mroute (you can also view mroute
>> counts to see that R3 is dropping, and R2 is forwarding).
>>
>> R1#ping 239.1.1.1 sou lo 0 re 100
>>
>> R2#sho ip mroute 1.1.1.1 239.1.1.1 | be \(
>> (1.1.1.1, 239.1.1.1), 00:00:37/00:03:27, flags: T
>> Incoming interface: FastEthernet0/0, RPF nbr 192.168.123.1
>> Outgoing interface list:
>> FastEthernet1/0, Forward/Sparse, 00:00:37/00:03:20
>>
>> R3#sho ip mroute 1.1.1.1 239.1.1.1 | be \(
>> (1.1.1.1, 239.1.1.1), 00:01:05/00:02:59, flags: PTX
>> Incoming interface: FastEthernet1/0, RPF nbr 192.168.234.2
>> Outgoing interface list: Null
>>
>> R2 is forwarding but R3 is the DR. Is this how you are testing?
>>
>>
>> On Fri, Oct 16, 2009 at 7:12 AM, karim jamali <karim.jamali_at_gmail.com>wrote:
>>
>>> Dear Experts,
>>>
>>> I understand that the DR from the server side, is the 1st router
>>> receiving
>>> the stream or in case of two routers one will be elected,and this router
>>> is
>>> the one that informs the RP that a stream exists (Register message),and
>>> the
>>> RP will send a register stop. On the client side,I understand that one of
>>> the two routers on the segment is supposed to communicate with the RP
>>> informing it that a client wants to listen to a certain group.
>>>
>>> The thing that is confusing me is from an article I read, I understood
>>> that
>>> the forwarder on a segment will be elected based on:
>>> 1)Best Administrative Distance to the souce
>>> 2)Best Metric to the source
>>> 3)Highest IP address.
>>>
>>>
>>> Scenario:
>>> PIM SPARSE MODE (RP on loopback of BB1)
>>> R1(STREAMER) -->LAN 1
>>> BB1-->LAN 1
>>> BB2-->LAN 1
>>>
>>> BB1-->LAN 2
>>> BB2-->LAN 2
>>> R4(CLIENT)-->LAN 2
>>>
>>> 1)When everything was left at its default.BB2 was the one forwarding on
>>> the
>>> segment,and this makes perfect sense since both BB1 and BB2 are connected
>>> to
>>> the stream (Same AD,Same Metric), so what determined the forwarder was
>>> the
>>> highest IP address (BB2).
>>>
>>> 2)When I used the command ip pim dr-priority <255> on BB1, the pim
>>> neighbor
>>> relationship was re-established and BB1 was the one forwarding on the
>>> segment. I used to think that the DR is only responsible for
>>> communicating
>>> with the RP and is not the one who will forward on the segment. I thought
>>> that the forwarder only depends on the 3 stated rules above. When I gave
>>> BB2
>>> a higher priority (ip pim dr-priority 256) it began forwarding again and
>>> BB1
>>> stopped forwarding.
>>>
>>> This is what is confusing me.
>>>
>>> I would be grateful if you can help me.
>>>
>>> Best Regards,
>>>
>>>
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>>>
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>>>
>>>
>>>
>>>
>>>
>>
>>
>> --
>> Bryan Bartik
>> CCIE #23707 (R&S), CCNP
>> Sr. Support Engineer - IPexpert, Inc.
>> URL: http://www.IPexpert.com <http://www.ipexpert.com/>
>>
>
>
>
> --
> KJ
>

-- 
Bryan Bartik
CCIE #23707 (R&S), CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com
Blogs and organic groups at http://www.ccie.net