Subject: Re: [Idr] I-D Action: draft-ietf-l2vpn-evpn-04.txt

From: Satya Mohanty <[email-masked]>
Date: Sat, 3 Aug 2013 17:37:11 +0000

Hi Ali,

I was only pointing out whether the route-target semantics will hold for the "value" 0; i.e. whether it should be allowed. I am copying idr to see if it will have any bearing on RT Filtering (RT Constraints functionality).

In any case, the approach you are suggesting about the two level check will work, but it makes the RT Constraint feature ineffective, it's a known problem (mapping from 10 bytes to 6 bytes), we did discuss this offline.

Best,
Satya

-----Original Message-----
From: Ali Sajassi (sajassi) [mailto:[email-masked]] 
Sent: Saturday, July 27, 2013 7:27 AM
To: Satya Mohanty; [email-masked]; [email-masked]
Cc: [email-masked]
Subject: Re: I-D Action: draft-ietf-l2vpn-evpn-04.txt

Hi Satya,

On 7/25/13 7:37 PM, "Satya Mohanty" <[email-masked]> wrote:

>Hi Ali,
>
>Let me clarify further.
>
>In Section 6 Ethernet segment, three ways to generate the esi are 
>described using (1)LACP (2)Root Bridge Mac address and priority and 
>(3)Configured value.
>
>From Section 8.6 ES-Import Route Target
>
>"This is a new transitive Route Target extended community carried with 
>the Ethernet Segment route. When used, it enables all the PEs connected 
>to the same multi-homed site to import the Ethernet Segment routes. The 
>value is derived automatically from the ESI by encoding the 6-byte MAC 
>address portion of the ESI in the ES-Import Route"
>
>Interpreted above (in absence of explicit mention) I would think that 
>regardless of how the ESI is configured, for purposes of deriving the 
>value of the ES-Import Route Target, one always extracts the six bytes 
>starting from the third byte (system mac placeholder).
>
>For instance, let's say somebody configures the esi using the third 
>option as 1.2.0.0.0.0.0.0.0.1, the system mac placeholder is 
>0.0.0.0.0.0 (bytes 3 till 8). This is the value which will be embedded 
>in the route-target field. Basically a value of 0.
>
>Wanted to clarify if this will be allowed? Normal Route Target formats 
>don't support value of 0, I think.

This would still work since this is a new RT derived based on MAC. And if someone configures MAC as 0, then the lower six bytes of this new RT will be zero. If you have multiple ESIs, with zero MAC, then the RTs for all these ESIs, will be zero which means the ES route messages will not be properly filtered by their RTs. However, they will eventually be properly filtered because the ESI values for these sites are different.

Cheers,
Ali 

>
>Best,
>Satya
>
>
>
>
>-----Original Message-----
>From: Ali Sajassi (sajassi) [mailto:[email-masked]]
>Sent: Thursday, July 25, 2013 10:05 AM
>To: Satya Mohanty; [email-masked]; [email-masked]
>Cc: [email-masked]
>Subject: Re: I-D Action: draft-ietf-l2vpn-evpn-04.txt
>
>Hi Satya,
>
>Section 6 doesn't talk about RT. How did you arrive at RT of zero?
>
>Regarding the nit. Agreed - the referenced section number is correct 
>but not the referenced title.
>
>Cheers,
>Ali
>
>On 7/25/13 2:21 AM, "Satya Mohanty" <[email-masked]> wrote:
>
>>Hi,
>>
>>With respect to sec 6.3 Ethernet Segment
>>
>>3. The ESI may be configured.
>>
>>
>>The bytes that comprise the Route-Target value i.e. bytes 2 till 8 of 
>>the configured esi, can they all be zeros?
>>AFAIK regular Route-Targets in 2-byte AS (as-num >= 1) or ip-address 
>>format (community-value >= 1), the bytes that comprise the value 
>>fields can't all be 0.
>>
>>Minor Nit: In sec 8.6, the reference to section 9.1 "Redundancy Group 
>>Discovery" is in error.
>>I guess the reference name needs to be changed.
>>
>>Best regards,
>>--Satya
>>
>>
>>
>>-----Original Message-----
>>From: [email-masked] [mailto:[email-masked]] On Behalf 
>>Of [email-masked]
>>Sent: Sunday, July 14, 2013 7:41 PM
>>To: [email-masked]
>>Cc: [email-masked]
>>Subject: I-D Action: draft-ietf-l2vpn-evpn-04.txt
>>
>>
>>A New Internet-Draft is available from the on-line Internet-Drafts 
>>directories.
>> This draft is a work item of the Layer 2 Virtual Private Networks 
>>Working Group of the IETF.
>>
>>	Title           : BGP MPLS Based Ethernet VPN
>>	Author(s)       : Ali Sajassi
>>                          Rahul Aggarwal
>>                          Wim Henderickx
>>                          Florin Balus
>>                          Aldrin Isaac
>>                          James Uttaro
>>	Filename        : draft-ietf-l2vpn-evpn-04.txt
>>	Pages           : 47
>>	Date            : 2013-07-14
>>
>>Abstract:
>>   This document describes procedures for BGP MPLS based Ethernet VPNs
>>   (EVPN).
>>
>>
>>The IETF datatracker status page for this draft is:
>>https://datatracker.ietf.org/doc/draft-ietf-l2vpn-evpn
>>
>>There's also a htmlized version available at:
>>http://tools.ietf.org/html/draft-ietf-l2vpn-evpn-04
>>
>>A diff from the previous version is available at:
>>http://www.ietf.org/rfcdiff?url2=draft-ietf-l2vpn-evpn-04
>>
>>
>>Internet-Drafts are also available by anonymous FTP at:
>>ftp://ftp.ietf.org/internet-drafts/
>>
>>
>>
>
>
>
>