Summary Statement: 
I'm pleased to see this work combining PIM domains and Bier domains. 
The one technical issue is how operators tell if things go wrong.  


Technical Issue:  This is one document that needs a manageability section. 
Can you include answers to the following question an operator might ask
before deployment? 

1) How do I detect if the PLI interface is misconfigured or has an error in the 
following cases:
a) DR election error 
b) packet duplication 
c) unexpected repeated drops 
d) failures in PIM domains. 

Editorial issues: 
1. Section 3.2.2, paragraph 2, sentences 1, and 2. 
Error: Run-on sentence with errors in comma usage 

Old text:/ 
   For instance, in a BIER domain connecting two PIM networks, a PLI can
   be used between BIER edge routers solely for multicast state
   communication, transmitting only PIM Join/Prune messages.  To prevent
   multicast stream duplication, PIM routers on either side of the BIER
   domain should establish PIM adjacency as per [RFC7761] to ensure DR
   election at the edge of BIER domain, as an example DR election
   between router D and F in above figure. /

New text:/
   For instance, in a BIER domain connecting two PIM networks, a PLI can
   be used between BIER edge routers solely for multicast state
   communication and transmit only PIM Join/Prune messages.  To prevent
   multicast stream duplication, PIM routers on either side of the BIER
   domain should establish PIM adjacency as per [RFC7761] to ensure DR
   election at the edge of BIER domain. An example of this DR election
   could be DR election between router D and F in above figure./

2. Section 3.3, sentence 2, lack of logic clarity 

If the PLI is enabled on an interface and Join/Prune message arrive, 
what other options exist except to process the message or to drop the message? 
If there are others, then this sentence needs to be changed.  

3. section 3.4 paragraph 3, starting In another example, grammar error. 

Old text:/
   In another example, if PLI is configured automatically, as an example
   in BIER case, when the downstream BIER Edge Router (DBER) is no
   longer reachable, the upstream BIER Edge Router (UBER) which is also
   a PIM Light Router can prune the <S,G> advertised toward the source
   on the PIM domain to stop the transmission of the multicast stream./

 The commas and the run-on sentence make this paragraph unclear. 
 Due to the text's unclear nature, I cannot understand the technical point. 

4. Section 3.5, paragraph 4, sentence 1, wrong use of active verb (lacking) 

Old text:/
   PIM Light lacking Hello messages, the PLI can be configured with the
   Connection ID IPv4 or IPv6 addresses used to establish the SCTP or
   TCP connection. /

New text: 

   PIM Light lacks Hello messages, the PLI can be configured with the
   Connection ID IPv4 or IPv6 addresses used to establish the SCTP or
   TCP connection./