RFC 6286 already updates RFC 4271.
Basically, RID is not unique. (ASN,RID) is unique. The only limitation on RID 
is that RID != 0.

Regards,
Jakob.

From: Gyan Mishra <hayabusa...@gmail.com>
Sent: Wednesday, February 3, 2021 9:42 PM
To: Jakob Heitz (jheitz) <jhe...@cisco.com>
Cc: Muthu Arul Mozhi Perumal <muthu.a...@gmail.com>; TULASI RAM REDDY 
<tulasiramire...@gmail.com>; bess@ietf.org; i...@ietf.org
Subject: Re: [Idr] [bess] Type 1 RD for Pure IPv6 network -- EVPN



On Wed, Feb 3, 2021 at 11:22 PM Jakob Heitz (jheitz) 
<jhe...@cisco.com<mailto:jhe...@cisco.com>> wrote:
<snip RFC4271>
   Syntactic correctness means that the BGP Identifier field represents
   a valid unicast IP host address.
</snip>

     Gyan> I do see that verbiage in section 6.2



   If the BGP Identifier field of the OPEN message is syntactically

   incorrect, then the Error Subcode MUST be set to Bad BGP Identifier.

   Syntactic correctness means that the BGP Identifier field represents

   a valid unicast IP host address.



BGP with IGP call back NH tracker checks the NH but how does BGP code validate 
the RIB that the router-id is a connected loopback but

and also advertised by IGP.  I have not tried it but if you set a bogus 
router-id would all the BGP peers go down.

I will try that in the lab.

IOS-XR does not have this check. Nothing breaks by violating this rule. IOS-XR 
implements RFC 6286.
I think you'll be hard pressed to find a router that checks this.
 Gyan> Agreed.  That is exactly what I thought.  I was going to try on IOS XR 
but you saved me some time and results as I expected.  I will try test RFC 6286 
on XR.  Have you tried doing IPv6 only peers on XR and with BGP identifier set 
unique to 4 octet IP address and see if that works.  I am guessing it would 
work as XR does not have the check.

    I  am not crazy about the RFC 6286 AS wide BGP identifier with 4 octet 
unsigned non zero integer.  Most operators are more comfortable having unique 4 
octet IP address as BGP identifier and I think would much rather do that as 
long as the check does not exist as even with enabling RFC 6286 and having AS 
wide unique identifier seems odd and scary to me as normally the BGP identifier 
must always be unique within the domain or breaks BGP.

dual stack edge over v6 core RFC 5565 is becoming more common for operators 
every day with SRv6 push and thus IPv6 only routers and running into this issue 
where now you have to enable RFC 6286.

I am thinking it maybe well worthwhile to write a draft that updates RFC 4271 
check as vendors don’t follow it anyway and as we all know not checking is not 
going to break anything and making so that for IPv6 only routers such as in a 
SRv6 core that the BGP identifier can remain a 4 octet IP and then operators 
now could keep the same unique BGP identifier IP you had on the router before 
you ripped it out of the core when transitioned to SRv6.
Regards,
Jakob.

--

[http://ss7.vzw.com/is/image/VerizonWireless/vz-logo-email]<http://www.verizon.com/>

Gyan Mishra

Network Solutions Architect

M 301 502-1347
13101 Columbia Pike
Silver Spring, MD

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