Rare project developers

[mc36 <>]

hi,
i go inline...
regards,
cs

On 2/18/22 17:53, Cristina Klippel Dominicini wrote:
> Hi Csaba,
>
> This is really great news \o/
>
> I talked with the group and the design choices seem very good for an initial 
> prototype. Thank you very much! We are going to execute the testcases and 
> provide feedback :-D
>
> Some initial doubts:
>
> > > 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
> This represents the links of the multicast tree and the syntax "1.1.1.4 
> 1.1.1.4" indicates a leaf, right?
exactly.. the general format is the following:
<encode for this address> <encode for this neighbor from the index table>+ ,
with the addition that if the neighbor address is itself, which is obviously 
not in the index table,
then it'll set the bit0 to indicate a 'and also process locally'....

> This representation is very good, because M-PolKA can represent structures 
> that are not exactly trees. For example, two branches that end in the same 
> leaf.
> Example: If you have an extra link between v2 and v4, the representation of 
> the multipath would be:
> tunnel domain-name 1.1.1.2 1.1.1.3 1.1.1.4, 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
> Is that right?
yesss, exactly... you got it right, you can describe arbitrary trees, and 
your above encoding should result in what you wanted to achieve....


> > >   sid#pin 3.3.3.2 /si 1111 /re 1111 /tim 11 /vr v2 /int lo2 /mul
> I didn't know you had this multicast pin! Super cool! Does it send the ICMP 
> packet to all the leaves?
this command basically the same pin(g) command, but as we instruct it to wait 
for multi(ple) responses within the timeout range...


> > > 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...
> I don't know if I understood correctly... These are bits from the output bitstream of the mod operation, right? 
yesss...

> So, if bitstream is 110 at v3, it will forward to 1st and 2nd neighbors (v4 and v5, in this example). 
exactly....

> But how does it correlates the neighbors with the srindex table (that 
> includes non-neighbors)?
just drop those examples, the output came from an intermediate state... :)
the correct encoding should had be 12 1100, the we're addressing 2nd and 3rd 
neighbor of v3...

> Regarding the routing, what are the structures we are reusing? How does 
> FreeRouter keep the list of neighbors and compute the routeid that will 
> produce the correct output bitstream in each node? I will explore the commits.
so finally i kept the srindex fields, and, while doing the shortest path, 
each index in that table got an ordered
list of neighbor indexes... assuming the link state database flooding 
finished completely, must be identical on
each router participating in an igp... and, when freerouter constructs the 
bitmap, it just converts the ips to
indexes over this ordered neighbor index table...

> If we use that approach of configuring two (or more) nodeids when you have 
> more than 16 igp peers, one needs to configure two (or more) loopbacks. Then, 
> the pipeline would have to combine the bitstreams considering some ordering 
> (the lower IP addr?). Also, it would have to check the number of available 
> loopbacks that have mpolka enabled. Do you already have any plans for this?
agreed... so these sr indexes are bound to addresses, and addresses are bound 
to nodes...
so one clearly sees that it have to emit with multiple bitmaps encoded for a 
single node...
right now, this check is not yet done.... the only check i do right now if i 
have to send
to two interfaces (let's say v3 have a tunnel to v2 and v4) then i can use 
two completely
different routeids on the two different interfaces...

regards,
cs


> Best regards,
> Cristina
> ________________________________________
> De: mc36 <>
> Enviado: quinta-feira, 17 de fevereiro de 2022 19:06
> Para: Cristina Klippel Dominicini; Rafael Silva Guimarães
> Cc: 
> Assunto: Re: [rare-dev] mpolka in rare
>
> hi,
> i've just covered mpolka with some test cases:
> https://github.com/mc36/freeRouter/commit/4caf6dc0657aade06d9cd38654b581e77465a971
> now i'll wait for your feedback before continuing with the dataplanes...
> regards,
> cs
>
>
> On 2/17/22 22:14, mc36 wrote:
> > hi,
> > sorry for the spam, but it forwards:
> >
> > sid#pin 3.3.3.2 /si 1111 /re 1111 /tim 11 /vr v2 /int lo2 /mul
> > pinging 3.3.3.2, src=1.1.1.2, vrf=v2, cnt=1111, len=1111, tim=11, gap=0, 
> > ttl=255, tos=0, flow=0, fill=0, sweep=false, multi=true, detail=false
> > !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> >
> > result=200%, recv/sent/lost/err=2222/1111/0/0, rtt 
> > min/avg/max/sum=0/0/2/12402, ttl min/avg/max=255/255/255
> > sid#
> >
> > the 200% success rate indicates that both v4 and v5 got the packets and they 
> > responded...
> >
> > this is the commit for this to happened:
> > https://github.com/mc36/freeRouter/commit/4a1d188521fa5a0fe8f8619c92f60dd44afa929e
> >
> > regards,
> > cs
> >
> >
> >
> >
> > On 2/17/22 21:11, mc36 wrote:
> > > 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
> > > > >
> > > > >
> > > > > ________________________________
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