Hi Tulasi and Muthu,

Yes, the numeric value here refers to the 4byte or 16byte unsigned value 
representation of the IP address field.
Maybe in the 7432-bis this can be stated explicitly.

We did envision this possibility in RFC 8584 (the HRW hash already takes care 
of the fact that the IP address could be either IPV4 or IPV6).

However, with respect to deployment do you have a case in mind of this “mixed 
v4/v6” that will necessitate such a tie-break?
I mean one of the MH PEs has an ipv4 originator address and the other a v6 
originator address.

Thanks,
--Satya


From: BESS <[email protected]> on behalf of TULASI RAM REDDY 
<[email protected]>
Date: Friday, February 5, 2021 at 5:17 AM
To: Muthu Arul Mozhi Perumal <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [bess] RFC 8584: EVPN DF Election - Originating Router's IP 
Address of different address family

Thanks Muthu.
Shouldn't numeric value here mean simply the 4byte or 16 byte unsigned value 
representation of the IP address field?
Thinking loudly on how to interpret numeric value  and the limitations here. 
Any comments?


each PE builds an ordered list of the IP

addresses of all the PE nodes connected to the Ethernet segment

(including itself), in increasing numeric value

Thanks,
Tulasi.
On Fri, Feb 5, 2021 at 3:15 PM Muthu Arul Mozhi Perumal 
<[email protected]<mailto:[email protected]>> wrote:
Hi Tulasi,

I think the problem is, there is no standard way to numerically compare IPv4 
with IPv6 addresses to form an ordered list. So, all the PEs multihomed to an 
ES may not always arrive at the same DF (or BFD in the case of single-active 
L-LINE service) with the default DF election algo. This is problematic (and may 
cause traffic loops). Hence, the default DF election algo works only when all 
PEs multihomed to an ES have Originating Router's IP Address of the same AF..

Regards,
Muthu

On Thu, Feb 4, 2021 at 7:58 PM TULASI RAM REDDY 
<[email protected]<mailto:[email protected]>> wrote:
Hi All,

As mentioned in the Problem Statement of RFC8584 Sec 1.3, Default DF algorithm 
is expected to have
all multihomed PEs to have Originating IP of the same address family.
Do we see any interop issue if the different address families are considered, 
i.e. ordering in
ascending order based on numerical value in Originating IP here? For IPv4 read 
4 octets as unsigned integer
and IPv6 is considered as 16 octet unsigned integer.

1.3<https://tools.ietf.org/html/rfc8584#section-1.3>.  Problem Statement

Default DF election algorithm assumes

that all the PEs who are multihomed to the same ES (and interested in

the DF election by exchanging EVPN routes) use an Originating

Router's IP address [RFC7432<https://tools.ietf.org/html/rfc7432>] of the same 
family.

Thanks,
TULASI RAMI REDDY N
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