Re: [Idr] WG Adoption call for draft-wang-idr-rd-orf-05.txt (2/4/2021 to 2/18/2021)

[Robert Raszuk <[e-mail]>]

Aijun & Gyan,

Let me try one more (hopefully last time) to explain to both of you - and
for that matter to anyone how supported this adoption.

Let's consider very typical Hub and Spoke scenario as illustrated below:

[image: image.png]

HQ1 is advertising two routes:

- one default with RDX1 with RT TO_SPOKE
- one or more specifics with RDX1 to the other HUBs

Now imagine HQ1 bought a new BGP "Optimizer" and suddenly is starting to
advertise 100000 /32 routes just to the other HUB with RT: TO_HUB.

[image: image.png]


So PE2 detects this as VRF with RDX2 on it got overwhelmed during import
with RT TO_HUB and starts pushing RDX1 (original RD) to RR to stop getting
those routes.

Well all great except now you are throwing baby with the water as all
spokes attached to PE2 which just import default route to HUB HQ1 also can
no longer reach their hub site as their default route will be removed.
Therefor they will have nothing to import with RT:TO_SPOKE

Further if RR "independently" decided ... oh let's push this ORF to PE1
then all of the spokes attached to perhaps even much more powerful PE3 can
also no longer reach their headquarters.

- - -

*Summary: *

The above clearly illustrates why the proposed solution to use RD for
filtering is in fact harmful.

See when you design new protocol extensions the difficulty is to not break
any existing protocols and deployments.

Hope this puts this long thread to rest now.


Thx,
Robert