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

Brian Dickson <> Thu, 20 April 2017 18:09 UTC

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From: Brian Dickson <>
Date: Thu, 20 Apr 2017 11:08:56 -0700
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To: "Alvaro Retana (aretana)" <>
Cc: Jared Mauch <>, "" <>
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Subject: 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
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TL;DR: BCPs don't work; operators vary in experience, diligence, etc;
vendors don't have common defaults; "open", "route-leaks", and "reject"
work differently and are all needed; code changes will have a long tail of
non-upgraded routers for a long time.

BCPs don't work - see BCP38 for the canonical example.

If operators were consistent (as in globally, uniform, ubiquitous without
exception) in applying best practices, these proposals would not even
exist. Their mere existence is proof that they are needed.

"reject" will only help once implemented, on upgraded or newly deployed
routers; ditto for "open"; "route-leaks" requires operator configuration,
but uses a transitive-optional attribute (and thus works alongside
non-upgraded routers). All three are needed, for their respective
attributes (on by default; stop leak origination; limit leak propagation).

The long tail on upgrades is what makes all three needed. No single one is
sufficient by itself, unless/until every router has been upgraded AND
configured. The three together are an imperfect but scalable and
incrementally deployable set of improvements with real global results.

Trying to move things in a productive direction.

My $0.02.


On Thu, Apr 20, 2017 at 10:50 AM, Alvaro Retana (aretana) <
> wrote:

> Jared:
> Hi!
> Not everyone in this thread was part of the initial conversations we had,
> so to give a little background:  I think (yes, still) that the document (as
> is in -05) should be marked as updating rfc4271 because it starts off
> saying that it “defines the default behavior of a BGP speaker…” and later
> (Section 2) describes specific changes pointing at pieces of rfc4271:
> “…MUST consider any routes advertised by an EBGP peer ineligible for route
> selection (section 9.1.1 [RFC4271])…”.
> Again, what gives me heartburn and the reason this document caught my
> attention is that change in the default – and from this thread, I can see
> that is an issue for others.
> Reading what you wrote below, about other potential options to achieve the
> same result, I agree with you that the bar doesn’t have to be as high as
> changing the default in rfc4271.  But the current document doesn’t reflect
> that.
> Maybe what we need is to describe the solution in a way that is not so
> rfc4271-specific.  Explain what the behavior should be (not how to achieve
> it), and even talk about the operational pain, and what operators should
> consider with the current not-specified behavior (which the document
> doesn’t do much of now).  I think that would be a very different document
> with a different set of discussion points, but one that could lead to the
> goal.
> During the early thread of this draft (a couple of years ago), several
> people suggested that the status should be a BCP.  I can see how a document
> explaining the pains and the considerations for Internet routers could be a
> BCP.
> Just trying to move the conversation forward.
> Alvaro.
> On 4/20/17, 12:07 PM, "Jared Mauch" <> wrote:
>         To make it clear: I don't want to break someones routers.
>         I do want to make it harder for someone to leak a table when they
> have a new router.
>         I don't belive the bar should be high, it can be embedded in
> whatever
> configuration/ZTP/automation/cut+paste template out there.  It could come
> in the form of yang over netconf, or a DHCPv6/DHCPv4 option.  It could
> come from a TXT record in DNS, or wahtever configuration method the vendor
> invents that is new and unimagined by th WG today.
>         I don't feel it requires updating 4271 to attain that goal, it's
> clear implementors have seen a path to do this today without having
> a concern with 4271, and I believe that Alvaro is wrong in the presumption
> this document updates 4271.  (I'm also willing to be told that I'm too
> rough
> for consensus :-).
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