[Xorp-users] Dynamic RP and other issues

[Pavlin Radoslavov]

> Rec≈R3---R1---R2--- rec
> 
> 
> 
> More specifically this:
> 
> 
> 
> Rec---(eth0 of  R3 | eth1 of R3)---(eth0 of  R1 | eth1 of R1)---
> 
> 
>   |
> 
>                                            Send---(eth0 of  R2 | eth1 of R2)
> ---
> addresses:
> 
> 
> (Rec: 10.0.80.12)---(R3: 10.0.80.10 | R3: 10.1.50.1)---(R1: 10.1.50.10 | R1:
> 10.1.200.1)---
> 
> 
>   |
> 
>                                               ( Send: 10.1.100.10)---(R2:
> 10.1.100.1 | R2: 10.1.200.10) ---
> 
> Rec=Receiver
> 
> Send=Sender
> 
> 
> 
> I have the above network and multicast worked well with static RP
> configuration. I have been setting VLC steaming video on sender and received
> it successfully on the receiver.
> 
> 
> 
> I am now trying to set up the bootsrap cand BSR/ cand RP but it can't find
> the RP. My config.boot files are at the end of the email.
> 
> I have a couple of questions about the dynamic RP configuration:
> 
> 1- how do you select the cand-bsr-by-vif-name and the cand-rp-by-vif-name? I
> 've selected them in a way that they point towards the sender. Is that right
> or it has nothing to do with it?

You can select any of the interfaces of a XORP router, as long as
this interface is enabled for multicast routing. In addition, all
other XORP routers must have Reverse-Path Forwarding information
toward the IP address of that interface. Typically that means that
you need to run an unicast routing protocol (or at least install the
appropriate static routes).

In your configuration I didn't see any static routes so you might
want to add them.

I see that inisde the Router 1 configuration you have the
"static-rps" section enabled.
If you want to use the Bootstrap mechanism you should delete all
static RPs (that overlap with the prefix(es) advertised by
Bootstrap), otherwise the result is unpredictable.

Note that if you want to use the Bootstrap mechanism, you don't have
to configure Bootstrap information in each XORP router. You need to
include the "bootstrap" section only if you want to configure a
router as a Cand-BSR and/or Cand-RP.

> 2- what is the minimum configuration for dynamic RP ?

You must have a Cand-BSR and a Cand-RP in at least one router, which
actually can be two different routers.
Then, again, you should not have any static RPs (in any multicast
router).

> On other topics:
> 
> 1-     what is the significance of the group-prefix 224.0.0.0? I know that
> after this address, the range of multicast addresses are found. Does it
> relate by anyway to the multicast group addresses used in the network?

The significance of group-prefix 224.0.0.0/4 is that with a single
configuration block you configure the Cand-RP or Cand-BSR for all
multicast groups. You can use any subprefix of the multicast address
space instead (except the link-local 224.0.0.0/8 which are not
routable).

> 2-     Do you have any information on SSM with XORP or SSM with VLC (other
> than enabling version 3 of IGMP?

Enabling IGMPv3 should be sufficient.
If you will be using ONLY SSM, then you don't need any RP-related
configuration (but it is better to keep the register_vif
interfaces).


> 3-     A stream is sent by multicast to a certain a multicast group address.
> It was received. What will happen if another stream was sent to the same
> multicast group address?

I presume the second stream is from a different source address.

Did the receiver use IGMPv1 or IGMPv2 to join the multicast group
(i.e., a group-specific (*,G) join).
If yes, then it should receive the second stream as well.

If the receiver used IGMPv3 to join the group address and a specific
source address (the address of the first sender) with a join like
(S1,G), then it will receive only the first stream. If it wants to
receive the second stream as well, then it needs to use another
IGMPv3 (S2,G) join.

Regards,
Pavlin