Rare project developers

[mc36 <>]

hi,
after applying the attached config, i see the following:

sid(cfg-if)#show ipv4 srindex v2
index  prefix      peers  bytes
2      ::/0               0
3      1.1.1.3/32  2 4 5  0
4      1.1.1.4/32  3      0
5      1.1.1.5/32  3      0

sid(cfg-if)#show ipv4 srindex v3
index  prefix      peers  bytes
2      1.1.1.2/32  3      0
3      ::/0               0
4      1.1.1.4/32  3      0
5      1.1.1.5/32  3      0

sid(cfg-if)#show ipv4 srindex v4
index  prefix      peers  bytes
2      1.1.1.2/32  3      0
3      1.1.1.3/32  2 4 5  0
4      ::/0               0
5      1.1.1.5/32  3      0

sid(cfg-if)#show ipv4 srindex v5
index  prefix      peers  bytes
2      1.1.1.2/32  3      0
3      1.1.1.3/32  2 4 5  0
4      1.1.1.4/32  3      0
5      ::/0               0

sid(cfg-if)#
sid(cfg-if)#show mpolka routeid tunnel2
iface      hop      routeid
hairpin11  2.2.2.2  00 00 00 00 00 00 00 00 00 00 74 90 0f 96 e9 fd

index  coeff     poly   crc    equal
0      0001046a  13101  13101  true
1      0001046b  1732   1732   true
2      0001046d  2031   2031   true
3      00010473  6      6      true
4      00010475  1      1      true
5      0001047f  1      1      true
6      00010483  13881  13881  true
7      00010489  55145  55145  true
8      00010491  38366  38366  true
9      0001049d  11451  11451  true

sid(cfg-if)#

the topology is the following:

      v3
v2-v3<
      v4

the tunnel is configured to point to v3 and v4

for the encoding, i reserved bit0 indicating that local processing is needed 
(end of tunneling, decapping, etc)
the rest of the bits indicate the need to forward to the peer in the srindex 
table, which, as an ordered list of
peers, must be identical on all the nodes executed the shortest path first...

the routeid seems to be correctly encoded as we find 6 (1st and 2nd 
neighbors) for nodeid 3, and 1 (decap) for nodeid 4 and 5...

next steps will be the forwarding to happen, then some test cases, and 
finally the dataplanes...

any opinion?

thanks,
cs




On 2/16/22 15:44, mc36 wrote:
> hi,
>
> On 2/16/22 15:22, Cristina Klippel Dominicini wrote:
> > Hi Csaba,
> >
> > Thanks for the feedback! We believe M-PolKA can tackle interesting use cases, 
> > and would be great to have it running on FreeRouter.
>
> yeahh, saw some in the paper and i'm also interested.... :)
>
> > > > my first impression was that after the mod operation, it's basically do what 
> > > > bier does, that is, we take the result, and interpret it as an outport 
> > > > bitmap, don't we?
> > Yes, exactly! We just changed the meaning of the portid polynomial and the pipeline for cloning the packets according to the bitmap. It will be really great if we can reuse part 
> > of the bier implementation for that end. Do you think we can do that for both freeRouter and Tofino? Then, we could run some experiments comparing BIER with m-PolKA :-)
>
> hopefully you'll able to do that...
>
>
> > > > and this is where we hit a limitation, depending on the size of crc is in 
> > > > use, we can only describe 16 output ports, which is clearly not enough...
> > Is it possible to use CRC32 for M-PolKA's implementation in FreeRouter?
>
> surely yess, we can use crc32, that one was also made parameterizable back 
> when polka was introduced... :)
> but that would reduce the core nodes expressable in the routeid by half...
>
>
> > > > my idea to overcome the above, what if we interpret mpolka mod result as a bitmap to this index table? it then raises the limitation to 16 igp neighbors per core node, which is 
> > > > more friendly...
> >
> > As we are already bound to the SR indexes, I think it is a reasonable 
> > reinterpretation.
> > Another simple way would be to have two nodeids per switch (or more), for example. Then, with the same routeid we could address half of the ports with nodeid1 and the other half 
> > with nodeid2. This would incur in two CRC operations to generate the bitmap.
> > We could also explore some other encoding techniques for the bitmap. Today is our weekly meeting at Ufes, so we will discuss with the group about the possibilities, and we give 
> > you a feedback on this subject.
>
> imho absolutely this is the way to follow instead of doing crc32,
> and one can easily have two loopbacks if one have more than 16 igp peers...
>
>
> > > > an other implementation idea is to use a different ethertype for mpolka to 
> > > > not confuse the unicast or multicast packets on the wire as they'll differ on 
> > > > handling...
> > Agreed! We also have some other ideas for failure protection and chaining 
> > that would change the header, and consequently, would need a different 
> > version code.
>
> fine... then i'll wait until you discuss with your colleges and then i'll 
> proceed with adding mpolka...
> since then i've done some digging into the code and imho mpolka will use 
> bier-id instead of srid because
> that beast already populates a thing bfrlist, which is the per node peer 
> index table we need for mpolka
> to interpret the bitmap over... it's just a config thing like the regular 
> polka and sr case...
> after this, the initial version will be able to address the multihoming use 
> case you discuss
> in your paper, moreover it'll be able to do the (iptv) headend usecase from 
> bier tests...
>
> regards,
> cs
>
>
> > Best regards,
> > Cristina
> >
> > ________________________________________
> > De: mc36 <>
> > Enviado: quarta-feira, 16 de fevereiro de 2022 03:21
> > Para: Cristina Klippel Dominicini; Rafael Silva Guimar   es
> > Cc: 
> > Assunto: mpolka in rare
> >
> > hi,
> > i went through your mpolka paper, first of all, congrats, nice work!
> > my first impression was that after the mod operation, it's basically do what 
> > bier
> > does, that is, we take the result, and interpret it as an outport bitmap, 
> > don't we?
> > and this is where we hit a limitation, depending on the size of crc is in use,
> > we can only describe 16 output ports, which is clearly not enough...
> > in freerouter, polka is bound to segment routing ids, and the result of the 
> > mod
> > is not a port but an sr index... my idea to overcome the above, what if we 
> > interpret
> > mpolka mod result as a bitmap to this index table? it then raises the 
> > limitation to
> > 16 igp neighbors per core node, which is more friendly...
> > an other implementation idea is to use a different ethertype for mpolka to not
> > confuse the unicast or multicast packets on the wire as they'll differ on 
> > handling...
> > afterall, i found it feasible both for software and dataplane implementations,
> > so it could become a drop-in replacement for the current ip multicast over 
> > bier...
> > any opinion?
> > thanks,
> > cs
> >
> >
> > ________________________________
> >
> > Esta mensagem (incluindo anexos) cont   m informa       o confidencial destinada a um usu   rio espec   fico e seu conte   do       protegido por lei. Se voc     n   o       o destinat   rio 
> > correto deve apagar esta mensagem.
> >
> > O emitente desta mensagem       respons   vel por seu conte   do e endere   
> > amento.
> > Cabe ao destinat   rio cuidar quanto ao tratamento adequado. A divulga       o, reprodu       o e/ou distribui       o sem a devida autoriza       o ou qualquer outra a       o sem conformidade 
> > com as normas internas do Ifes s   o proibidas e pass   veis de san       o disciplinar, c   vel e criminal.




conf t
router lsrp4 2
 vrf v2
 router-id 1.1.1.2
 segrout 10 2
 redistribute connected
 exit
interface loopback2
 no description
 vrf forwarding v2
 ipv4 address 1.1.1.2 255.255.255.255
 exit
router lsrp4 3
 vrf v3
 router-id 1.1.1.3
 segrout 10 3
 redistribute connected
 exit
interface loopback3
 vrf forwarding v3
 ipv4 address 1.1.1.3 255.255.255.255
 exit
router lsrp4 4
 vrf v4
 router-id 1.1.1.4
 segrout 10 4
 redistribute connected
 exit
interface loopback4
 vrf forwarding v4
 ipv4 address 1.1.1.4 255.255.255.255
 exit
router lsrp4 5
 vrf v5
 router-id 1.1.1.5
 segrout 10 5
 redistribute connected
 exit
interface loopback5
 vrf forwarding v5
 ipv4 address 1.1.1.5 255.255.255.255
 exit
hairpin 1
 exit
interface hairpin11
 no description
 vrf forwarding v2
 ipv4 address 2.2.2.1 255.255.255.252
 router lsrp4 2 enable
 mpolka enable 2 66666 10
 mpls enable
 exit
interface hairpin12
 no description
 vrf forwarding v3
 ipv4 address 2.2.2.2 255.255.255.252
 router lsrp4 3 enable
 mpolka enable 3 66666 10
 mpls enable
 exit
hairpin 2
 exit
interface hairpin21
 no description
 vrf forwarding v3
 ipv4 address 2.2.2.5 255.255.255.252
 router lsrp4 3 enable
 mpolka enable 3 66666 10
 mpls enable
 exit
interface hairpin22
 no description
 vrf forwarding v4
 ipv4 address 2.2.2.6 255.255.255.252
 router lsrp4 4 enable
 mpolka enable 4 66666 10
 mpls enable
 exit
hairpin 3
 exit
interface hairpin31
 no description
 vrf forwarding v3
 ipv4 address 2.2.2.9 255.255.255.252
 router lsrp4 3 enable
 mpolka enable 3 66666 10
 mpls enable
 exit
interface hairpin32
 no description
 vrf forwarding v5
 ipv4 address 2.2.2.10 255.255.255.252
 router lsrp4 5 enable
 mpolka enable 5 66666 10
 mpls enable
 exit
int tun2
 tunnel vrf v2
 tunnel source loopback2
 tunnel destination 1.1.1.99
 tunnel domain-name 1.1.1.2 1.1.1.3 , 1.1.1.3 1.1.1.4 1.1.1.5 , 1.1.1.4 
1.1.1.4 , 1.1.1.5 1.1.1.5
 tunnel mode mpolka
 vrf for v2
 ipv4 addr 3.3.3.1 /30