[c-nsp] MSDP and my limited knowledge question

Tue Sep 4 04:12:12 EDT 2012

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

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?)
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

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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>> >
>>
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>
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