Hi Ben,

> Regarding whether we need to standardise the Network-to-server "API"
> for ALTO, my opinion is that we do not.

I highly agree with that opinion. Any attempt to standardize ALTO server API to network is a clear attempt to limit it's range of functionality.

Number of reasons:

- Attaching an ALTO server as passive IGP node is not an issue. Using
  BGP to propagate local IGP area topology to ALTO server attached to
  such area is really highly questionable improvement

- Using BGP to propagate remote IGP topologies is just a way .. clearly
  there are other ways to propagate IGP topologies from remote areas

- As defined today draft-gredler-bgp-te-00 is very selective in what
  information is propagted from LSDB or TEDB. Each addition of such
  information would require a new BGP extension definition. This will
  block ALTO innovation. There were already proposals stated during the
  last IETF to carry entire LSDB in BGP as opaque information however
  those are beyond the scope of this WG discussion.

- ALTO servers even today can benefit from other ways to get network
  information which would not have to be carried in BGP.

Many thx,
R.







Authors, Colleagues,

The meeting minutes from IETF 80 record:

"Jan Medved presents Network-to-server API.

   Jan Seedorf: scope of this work is explicitly excluded in RFC 5693
   ALTO WG scope description. Enrico: this is new work, currently not
   in the charter. We should hear it. Jan S.: we need to discuss if we
   need to standardized it. Eric: it does, but maybe not now."

Regarding whether we need to standardise the Network-to-server "API" for ALTO, 
my opinion is that we do not.

Extracting network topology by passively listening to routing protocols for 
various purposes including aiding with operations, diagnostics, root cause 
analysis, management, capacity planning, traffic engineering, etc. is not a new 
idea. There are multiple products on the market to enable operators to do just 
that.

An ALTO server that follows a similar approach as a mechanism to import network 
topology into its network topology/map/cost database is a reasonable 
proposition but in my opinion the ALTO WG should not attempt to standardise how 
a ALTO server should perform such integration with an operator's routing 
control plane(s), for example  because:

* Extracting network topology is not an interoperability issue between ALTO 
servers. Each ALTO server can extract the network topology independently and if 
the topology needs to be distributed between ALTO servers then it is an ALTO 
Server-Server API that needs standardising *not* an ALTO Server-Network API. 
Interoperation between an ALTO Server and the underlying network(s) is a solved 
problem as is demonstrated by the numerous interoperable implementations of 
routing protocols.

* Attempting to standardise a single approach is likely to limit the applicability of 
ALTO (or the relevancy of the ALTO Server-Network "API standard") because it is 
unlikely we would be able to converge on a single routing protocol that would satisfy the 
preferences of all operators that are likely to deploy an ALTO server.

Ben

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