Robert,
On 17/05/2022 14:14, Robert Raszuk wrote:
Ok cool - thx Peter !
More general question - for any FlexAlgo model (incl. SR):
Is fallback between topologies - say during failure of primary one -
only allowed on the ingress to the network ?
no. Fallback between flex-algos has never been a requirement and is not
part of the flex-algo specification.
I consider it a dangerous thing to do. It may work under certain
conditions, but may cause loops under different ones.
thanks,
Peter
If so the repair must be setup on each topology, otherwise repair will
be long as it would need to wait for igp flooding and ingress switchover
trigger ?
Obviously for IP flex algo it would be much much longer as given prefix
needs to be completely reflooded network wide and purged from original
topo. Ouch considering time to trigger such action.
Many thanks,
R.
On Tue, May 17, 2022, 13:35 Peter Psenak <[email protected]
<mailto:[email protected]>> wrote:
Hi Robert,
On 17/05/2022 12:11, Robert Raszuk wrote:
>
> Actually I would like to further clarify if workaround 1 is even
doable ...
>
> It seems to me that the IP flexalgo paradigm does not have a way for
> more granular then destination prefix forwarding.
that is correct. In IP flex-algo the prefix itself is bound to the
algorithm.
>
> So if I have http traffic vs streaming vs voice going to the same
load
> balancer (same dst IP address) there seems to be no way to map some
> traffic (based on say port number) to take specific topology.
no, you can not do that with IP flex-algo.
>
> That's pretty coarse and frankly very limiting for applicability
of IP
> flex-algo. If I am correct the draft should be very
explicit about this
> before publication.
please look at the latest version of the draft, section 3:
https://datatracker.ietf.org/doc/html/draft-ietf-lsr-ip-flexalgo#section-3
<https://datatracker.ietf.org/doc/html/draft-ietf-lsr-ip-flexalgo#section-3>
thanks,
Peter
>
> Kind regards
> R.
>
> On Tue, May 17, 2022 at 12:01 PM Robert Raszuk <[email protected]
<mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>
> Folks,
>
> A bit related to Aijun's point but I have question to
the text from
> the draft he quoted:
>
> In cases where a prefix advertisement is received in both
a IPv4
> Prefix Reachability TLV and an IPv4 Algorithm Prefix
Reachability
> TLV, the IPv4 Prefix Reachability advertisement MUST be
preferred
> when installing entries in the forwarding plane.
>
> Does this really mean that I can not for a given prefix say
/24 use
> default topology for best effort traffic and new flex-algo
topology
> for specific application ?
>
> Is the "workaround 1" to always build two new topologies for such
> /24 prefix (one following base topo and one new) and never
advertise
> it in base topology ?
>
> Is the "workaround 2" to forget about native forwarding and
use for
> example SR and mark the packets such that SID pool
corresponding to
> base topology forwarding will be separate from SID pool
> corresponding to new flex-algo topology ?
>
> Many thx,
> Robert
>
>
> ---------- Forwarded message ---------
> From: *Acee Lindem via Datatracker* <[email protected]
<mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>>
> Date: Mon, May 16, 2022 at 3:36 PM
> Subject: [Lsr] Publication has been requested for
> draft-ietf-lsr-ip-flexalgo-06
> To: <[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>>
> Cc: <[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>>,
> <[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>>,
> <[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>>,
<[email protected] <mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>>
>
>
> Acee Lindem has requested publication of
> draft-ietf-lsr-ip-flexalgo-06 as Proposed Standard on behalf
of the
> LSR working group.
>
> Please verify the document's state at
> https://datatracker.ietf.org/doc/draft-ietf-lsr-ip-flexalgo/
<https://datatracker.ietf.org/doc/draft-ietf-lsr-ip-flexalgo/>
> <https://datatracker.ietf.org/doc/draft-ietf-lsr-ip-flexalgo/
<https://datatracker.ietf.org/doc/draft-ietf-lsr-ip-flexalgo/>>
>
>
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