There's no knob for RFC 6286. RID cannot be assumed to be unique across ASes. 
Period. Well, unless you have control over all the ASes. What do you mean by 
the knob exactly?

Regards,
Jakob.


On Feb 4, 2021, at 6:55 AM, Gyan Mishra <[email protected]> wrote:



Hi Acee

Understood the uniqueness by ASN,RID per RFC 6286 AS wide BGP identifier for 
the IPv6 only SRv6 core use case.

What I am uncomfortable as an operator with is the AS wide BGP identifier on 
every core router using the RFC 6286 knob for the SRv6 use case.  If we could 
continue to use unique IPv4 address  on every core router in the SRv6 IPv6 only 
core use case I would be more comfortable then using the RFC 6286 knob.

Kind Regards

Gyan

On Thu, Feb 4, 2021 at 6:09 AM Acee Lindem (acee) 
<[email protected]<mailto:[email protected]>> wrote:
Hi Gyan,
Agree with Jakob. There is no reason for the BGP Identifier to be a unique IPv4 
address. Consider an IPv6 only AS. However, there is nothing precluding you 
from using an IPv4 address if you are uncomfortable.

Thanks,
Acee

From: BESS <[email protected]<mailto:[email protected]>> on behalf of 
"Jakob Heitz (jheitz)" 
<[email protected]<mailto:[email protected]>>
Date: Thursday, February 4, 2021 at 12:52 AM
To: Gyan Mishra <[email protected]<mailto:[email protected]>>
Cc: TULASI RAM REDDY 
<[email protected]<mailto:[email protected]>>, Muthu Arul Mozhi 
Perumal <[email protected]<mailto:[email protected]>>, 
"[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>, 
IDR List <[email protected]<mailto:[email protected]>>
Subject: Re: [bess] [Idr] Type 1 RD for Pure IPv6 network -- EVPN

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 <[email protected]<mailto:[email protected]>>
Sent: Wednesday, February 3, 2021 9:42 PM
To: Jakob Heitz (jheitz) <[email protected]<mailto:[email protected]>>
Cc: Muthu Arul Mozhi Perumal 
<[email protected]<mailto:[email protected]>>; TULASI RAM REDDY 
<[email protected]<mailto:[email protected]>>; 
[email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>
Subject: Re: [Idr] [bess] Type 1 RD for Pure IPv6 network -- EVPN



On Wed, Feb 3, 2021 at 11:22 PM Jakob Heitz (jheitz) 
<[email protected]<mailto:[email protected]>> 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.

--

[Image removed by sender.]<http://www.verizon.com/>

Gyan Mishra

Network Solutions Architect

M 301 502-1347
13101 Columbia 
Pike<https://www.google.com/maps/search/13101+Columbia+Pike?entry=gmail&source=g>
Silver Spring, MD

--

[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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