Re: [Idr] IETF LC for IDR-ish document <draft-ietf-grow-bgp-reject-05.txt> (Default EBGP Route Propagation Behavior Without Policies) to Proposed Standard

[Nick Hilliard <[e-mail]>]

Enke Chen wrote:
> The CLI migration falls apart when a customer skips releases and jumps
> from one release ("permit all") to another ("deny all").

Enke,

config downgrading is why the "downward-compatible-config" IOS
configuration command exists.  Config upgrading is relatively
straightforward, although it takes years to implement.

Changing defaults and commands is something which has happened on many
occasions over the lifetime of IOS, from radical config breaking "ip
classless", or my personal favourite, "mop enabled" in the interface
config mode, which changed default backwards and forwards on several
occasions, not just once (I'd love to hear the back-story about how and
why that happened, btw).  Other well known examples include the modular
QoS config mechanism which removed the older qos config mechanisms.

Just because a large vendor doesn't like changing defaults, that doesn't
mean it's not a sensible thing to standardise.

No-one is under any illusion that there is a cost to vendors
implementing this but right now, the cost of not doing it is borne by
other people, and we're tired of it.

Nick