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

[<[e-mail]>]

> From: Idr [e-mail]  > Sent: Thursday, April 20, 2017 11:29 AM
> 
 > Job,
 > 
 > > From: Job Snijders [mailto:[e-mail]]  > Sent: Thursday, April 20, 2017 10:58 AM
 > >
 >  > On Wed, Apr 19, 2017 at 10:12:48PM +0000, [e-mail] wrote:
 >  > > Thanks John for bringing this in IDR.
 >  > >
 >  > > I admit that I was not following this subject so my comments might be redundant or
 > even
 >  > stupid.
 >  > >
 >  > > 1) Am I missing something or would this break all existing EBGP
 >  > > sessions deployed with no policy?
 >  >
 >  > Yes, you are missing the fact that a wild variety of defaults has been
 >  > deployed in the wild:
 >  >
 >  >     o some reject on ingress, promiscuous on egress
 >  >     o some reject on both ingress and egress
 >  >     o some accept and announce everything
 >  >
 >  > This documents aims to align those on a singular safe default: on EBGP
 >  > you'll need to configure a policy for something to happen.
 > 
 > My comment still applies to some implementations and some deployments.
 > 
 >  > > If so this would definitely not be deployment friendly. Especially for
 >  > > BGP/MPLS VPN networks using EBGP for PE-CE routing and which have
 >  > > little use of filtering policies.
 >  >
 >  > This is what release notes are for.
 > 
 > Possible awareness does not change the point that this forced change of default behavior is
 > not deployment friendly for non Internet applications.
 > 
 >  > > 2) BTW, what is exactly eligible as an "import policy"? e.g.
 >  > > - is an explicit policy capping the number of received routes eligible as an "import
 > policy"?
 >  > > - is Route Target filtering (either automatic or manual) a routing policy?
 >  > >
 >  > > Same question of "export policy". e.g.
 >  > > Is an expert policy tagging community eligible?
 >  >
 >  > i do not understand what you mean. Can you elaborate or phrase
 >  > differently?
 > 
 > Can this document define what he means by "configured export policy".  Possibly by
 > referring to standardized yang models.

Because I think the document means "configured route (re)distribution/advertisement policy".
Possibly this was implied by the word "export" but one could read this as any outbound policy, while a policy setting some communities would probably not help much.

--Bruno (sorry for the spam)

 > Alternatively, it looks like the document means that "by default a BGP speaker MUST NOT
 > advertise any routes to an EBGP peer". Which would solve the problem by not referring
 > anymore to configured export policy.
 > 
 >  > > 3) From the introduction
 >  > > "   There are BGP routing security issues that need to be addressed to
 >  > >    make the Internet more stable. [...]  This document provides guidance to BGP
 > [RFC4271]
 >  > >    implementers to improve the default level of Internet routing
 >  > >    security."
 >  > >
 >  > > Does this mean that this proposition should be restricted to Internet
 >  > > routing? (while BGP is used for many others applications)
 >  >
 >  > It is restricted to EBGP.
 > 
 > Yes, also, but this seems orthogonal to me.
 > So to rephrase, does this mean that this proposition should be restricted to EBGP sessions
 > used for Internet routing? (as EBGP is used for many others applications)
 > 
 >  >
 >  > > 4) Alternatively, there could be a (capability) signaling during the
 >  > > OPEN of the EBGP session. With one end requesting this behavior to its
 >  > > peer. (or alternatively it's peer advertising the presence of a policy
 >  > > and the receiver taking its own decision).
 >  > >
 >  > > Possibly, some of the requirements may already be addressed by
 >  > > configuring a policy limiting the number of routes acceptable from a
 >  > > peer/customers, and closing the EBGP sessions when this limit is
 >  > > reached. This seems this would catch customers/peers advertising the
 >  > > full routing by mistake/misconfiguration.
 >  >
 >  > no.
 > 
 > Can this document better describe the problem statement?
 > Please find below my reading of the current text
 > 
 > "   There are BGP routing security issues that need to be addressed to make the Internet
 > more stable."
 > Agreed, but not very specific.
 > 
 > "  Route leaks [RFC7908] are part of the  problem, but software defects or operator
 > misconfigurations can  contribute too."
 > - Route leaks seem to be already worked on by draft-ymbk-idr-bgp-open-policy or draft-ietf-
 > idr-route-leak-detection-mitigation. Plus this document is not a solution to route leak
 > - Software defect won't probably be addressed by this proposal
 > - Misconfiguration won't probably be addressed by this proposal.
 > 
 > So, although I agree that requiring explicit export and import for EBGP session used in the
 > Internet is probably an improvement, I disagree with changing the default of existing
 > deployed EBGP sessions for non Internet usages, as this would breaks current deployment.
 > At minimum, this should be restricted to new configured sessions ... but even this would
 > break existing provisioning scripts so this is still not so deployment friendly.
 > 
 > King regards,
 > -- Bruno
 > 
 >  > Kind regards,
 >  >
 >  > Job
 > 
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