[c-nsp] MSDP and my limited knowledge question

Wed Sep 5 04:03:00 EDT 2012

Hello and sorry for the delay in answering.
Tons of messages and all very helpful; now the issue makes sense.

On 9/4/12 10:12 AM, Adam Vitkovsky wrote:
> As Paul said IGMP register messages are supposed to be handled by the router
> elected as designated querier for the local subnet
> Though AFAIK IGMP register process is only used by the m-cast receivers not
> the sources
> To my knowledge sources just start streaming the m-cast traffic and omit the
> IGMP register process -the router on a local subnet elected as designated
> forwarder would pick up the stream and begin the PIM register process
> towards the RP -encapsulating the m-cast packets into unicast packets
> towards the RP (assuming Sparse Mode)
>
> Mihai
> Is the below output created only after you start streaming from the source
> please?
>   (10.10.10.1, 233.224.26.1), 00:00:05/00:02:57, flags: PT
>       Incoming interface: GigabitEthernet1/48, RPF nbr 192.168.1.2
>       Outgoing interface list: Null
Yes, it is created after I start streaming from the source.
>
> I'm not really sure what fails here why the c4900 doesn't originate the SA
> msg after the source has registered with the RP (try what debug pim says)
> I'm wondering whether the Linux box picks up the m-cast stream sourced from
> loopback and acts as first-hop router with directly connected source (but I
> guess you don't have PIM enabled on the box right?)
right, no pim enabled.

> Or it just simply routes/forwards the m-cast stream  sourced by loopback out
> the LAN interface towards the c4900 acting as pure host/source
Linux simply sends a multicast stream into the C4900 configured as RP 
and yes, seems there's no one doing the PIM register (linux acts like a 
pure multicast source).
I'm wondering if I can trick this process to work without installing 
another box as a middle man between the Linux and the C4900.

--
mihai
>
>
> adam
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Paul Cosgrove
> Sent: Monday, September 03, 2012 11:07 PM
> To: David Prall
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] MSDP and my limited knowledge question
>
> Oops think i misread there... thought you were fixing it with a static to
> the interface (a method which it just occurred to me may not work). Your
> indirect static means the c4900 RP will not be DR. If you are using a router
> as a test source, with no other intermediate router acting as DR, adding the
> RP definition to that is worth a try but may not help if the SRC IP is local
> . The source IP will probably need to be within a connected range of the
> incoming interface for the register to be sent.
> On 3 Sep 2012 21:18, "Paul Cosgrove" <paul.cosgrove.lists at gmail.com> wrote:
>
>> Msdp source active messages are sent to peers in response to pim
>> registers the router receives.
>>
>> Pim registers are the responsibility of the DR on the same subnet as
>> the source.
>>
>> When you have the static route the c4900 sees the source as directly
>> attached, making it both the RP and the DR responsible for sending the
>> registers (to itself). Without the static route the router receives
>> the data stream, but doesn't know that it should be the router
>> advertising it to the RP, and the RP doesn't know the stream originates in
> its domain.
>> Paul.
>> On 3 Sep 2012 20:55, "David Prall" <dcp at dcptech.com> wrote:
>>
>>> PIM is running between the two systems or you have a static mroute
>>> configured. What does "sh ip rpf 10.10.10.1"
>>>
>>> David
>>>
>>> --
>>> http://dcp.dcptech.com
>>>
>>>
>>> -----Original Message-----
>>> From: Mihai Tanasescu [mailto:mihai at duras.ro]
>>> Sent: Monday, September 03, 2012 3:32 PM
>>> To: David Prall
>>> Cc: cisco-nsp at puck.nether.net
>>> Subject: Re: [c-nsp] MSDP and my limited knowledge question
>>>
>>> On 9/3/12 9:02 PM, David Prall wrote:
>>>> You're using a GLOP group, so you are AS number 57370?
>>>>
>>>> You do have "ip pim rp-address 192.168.1.2" configured? I am
>>>> assuming
>>> the
>>>> 192.168.1.2 is the MSDP source-address and the BGP source-address.
>>> Yes, that's configured.
>>> This issue only happens when that subnet is not directly connected on
>>> the interface toward the source and when I have a static route toward it.
>>> I can also see that my source is sending the stream (it is a Linux
>>> that I use for testing and as such I can easily do a tcpdump).
>>>
>>>> David
>>>>
>>>> --
>>>> http://dcp.dcptech.com
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: cisco-nsp-bounces at puck.nether.net
>>>> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Mihai
>>>> Tanasescu
>>>> Sent: Monday, September 03, 2012 2:13 PM
>>>> To: cisco-nsp at puck.nether.net
>>>> Subject: [c-nsp] MSDP and my limited knowledge question
>>>>
>>>> Hi all,
>>>>
>>>> I have a simple test setup where I'm most likely failing to do
>>>> something right.
>>>>
>>>> It basically looks like this:
>>>>
>>>> My PC --- CPE --- L3 transport network not under my control  --
>>>> their router (MSDP + BGP + RP here) ---- ( MSDP+ BGP + RP here)
>>>> C4900
>>>> (192.168.1.1) -- (192.168.1.2) - multicast source (S)
>>>>
>>>> I announce (and originate on the C4900) through BGP the multicast
>>>> sources subnet let's call it: 10.10.10.0/29 which I send to my
>>>> provider (along with the RP/MSDP IP).
>>>> MSDP peers are up, everything seems ok.
>>>>
>>>> a) if I put the 10.10.10.0/29 class as directly connected (between
>>> C4900
>>>> and S) instead of the 192.168.1.1 and 192.168.1.2 from above -> all
>>>> works ok and I can view the stream on my PC with VLC.
>>>>
>>>> I also see:
>>>>
>>>> (10.10.10.1, 233.224.26.1), 00:00:09/00:02:58, flags: PTA
>>>>      Incoming interface: GigabitEthernet1/48, RPF nbr 0.0.0.0
>>>>      Outgoing interface list: Null
>>>>
>>>> b) if I put:
>>>> 10.10.10.1/29 or /32 configured on S on a Loopback interface and on
>>>> C4900:
>>>> ip route 10.10.10.0 255.255.255.240 192.168.1.2
>>>>
>>>> then I only have:
>>>>
>>>> (10.10.10.1, 233.224.26.1), 00:00:05/00:02:57, flags: PT
>>>>      Incoming interface: GigabitEthernet1/48, RPF nbr 192.168.1.2
>>>>      Outgoing interface list: Null
>>>>
>>>> the A flag - MSDP Adv candidate is missing and if I do a: show ip
>>>> msdp peer <peer ip> advertise-sa, then I see
>>> nothing.
>>>> What am I missing ?
>>>> Am I running into any check that I am failing ?
>>>>
>>>> Can you help me out ?
>>>> This subject is quite new to me.
>>>>
>>>> Thanks,
>>>> Mihai
>>>>
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