The MPLS-OPS Archive

["M. ELK" <elkou141061@hotmail.com>]

Hi

As non educated opinion i guess that Multicast is only possible and scalable 
with the P2MP LSP
feature . For the P to get involved in multicast is a BAD idea .

Started to read the P2MP RSVP draft , but realized that reading such draft 
is not the job U do at the end of the working day (not so easy with many new 
confusing -at least for me -terminology) .

Though about this simple (naive) approah , what do U think ??



PE1-------P1--------P2-------P3---(toward PE2,PE3,PE4 )
                         !
                         !-----P4---(sub netw toward PE5,PE6,PE7)

The ingress PE (PE1) will initiate a seperate RSVP-TE LSP to each Egress 
(PE2,...PE7).
Total = 6 RSVP-TE .
All the 6 RSVP-TE will have an extra properties (new object) which function 
as an indication that
they belong to the same group . let us call it group-ID .
let say that L1 to L6 are the label recieved for the 6 LSP .
PE1 will send RSVP Group-request  msg (new msg to be defined) to P1 , the 
msg contain the Group-ID .
P1 will respond with Group-Rely msg with label "L7" .
which mean if U send me a packet  with top label "L7" i will replicate it as 
if i recieved 6 packet
with L1 to L6 as top label .

P1 could also send Group-request to P2 .
P2 will reply with Group-reply with label 200 .
Now ,P1 when recieve a packet with Top label 7 ,it will not replicate it  
just swap 7 with 200 and forward to P2.

P2 will send to P3 and P4 a Group-Request MSG , P3 reply with label 300 and 
P4 with label 400.
when P2 recieve a label with 200 , it will be replicated as : 1) with top 
label 300 to P3 .
and 2) with top label 400 to P4 .

..etc .

the above considered ordered mode ,but independent mode is also possible .
ex: P2 will notice that their 3 LSP going through P3 have the same Group-ID 
so it could initiate
   a Group-Request msg .

Let us say that PE1 in addition to sending a stream to the 6 PE's need also 
at the same time to send another stream to PE2 and PE5 only  .

PE1 send a group-Request with the Group-ID but it contain the label L2 and 
L5 .
P1 will repy with Group-reply and label 10.

P1 will send a grou-request to P2 with label L2 and L5 (assume same label 
advertized by P3 ,just
for simplicitly) ,P2 will reply with label 210 .

P2 will not send group-request with label L2 to P3 neither a Group-Request 
with Label L5 to P4 .
as it is a branching point and the nbr of label is just 1 .

For stream from PE1 to PE2 and PE5 , PE1 will send a packet with top label 
10 ,
P2 will swap label 10 with label 210 and forward to P3.
P3 will replicate the packet , one copy with label L2 toward P3 . other copy 
with label L5 to P4.


The advantage :
the same 6 LSP used to send to all the PE's or to any combination .
the RSVP-TE protocol is not changed must still it follow the rule of P2P .
the intermediate node do not get involved in the complexity of P2MP .

Pls comments.

Brgds

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