Re: [Bier] Comments on draft-ietf-bier-bier-yang

[Xiejingrong <[e-mail]>]

Hi Sandy,
Please see my comments below in-line:

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Sent: Monday, April 15, 2019 2:31 PM
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Cc: Xiejingrong <[e-mail]>; [e-mail]; [e-mail]; [e-mail]
Subject: Re:[Bier] Comments on draft-ietf-bier-bier-yang


Hi Senthil, Jingrong,



Thank you for your review and comments.

I agree with your modification comments about the address-family.

[xjr] thanks for having the same understanding about addr-family.

About the encapsulation part:

   |        +--rw encapsulation* [bitstringlength]

   |           +--rw bitstringlength               uint16

   |           +--rw encapsulation-type            enum

   |           +--rw max-si?                       rt-type: uint16

   |           +--rw bift-id-base?                 rt-types: bift-id

Do you think if it's better to use both BSL and encapsulation-type as the keys?

[xjr] There is description from rfc8401 section 6.2 that, a sub-sub-tlv with a specific bsl can be allowed only once within a sub-domain.

   If the same BitString length is repeated in multiple sub-sub-TLVs

   inside the same BIER Info sub-TLV, the BIER Info sub-TLV MUST be

   ignored.

This allow different BSLs with different encapsulation, as Senthil mentioned, but it may be more clean to use multiple sub-domains for different encapsulations, instead of using different encapsulations in a sub-domain.



About the load-balance-num, IMO it's not necessary to define it in BIER.

BIER ECMP depends on IGP's ECMP capability. And as Jingrong said, there may be different ECMP path number in different routers.

So at most a ECMP enable capability can be showed in BIER model (sub-domain), it's not necessary to define the specific number.

[xjr] Are you talking about section 6.7.1 Non-deterministic ECMP of 8279 ?

I think section 6.7.2 Deterministic ECMP is more general, and in this case, the BIER ECMP number is the number of BIFT tables constructed for a sub-domain.

In this case, the BIER ECMP number is a configured number other than the default number <1>, which should be supported anyway (no matter what the ECMP paths to BFERs).

Thanks,

jingrong

Thanks,

Sandy


原始邮件
发件人：SenthilDhanaraj <[e-mail]<mailto:[e-mail]>>
收件人：Xiejingrong <[e-mail]<mailto:[e-mail]>>;
抄送人：陈然00080434;[e-mail] <[e-mail]<mailto:[e-mail]>>;[e-mail] <[e-mail]<mailto:[e-mail]>>;
日 期 ：2019年04月15日 13:45
主 题 ：Re: [Bier] Comments on draft-ietf-bier-bier-yang
Dear Yang Authors,
1) I agree to Jingrong's comment that "Same sub-domain cannot be binded to both IPv4 and IPv6 underlay". Pls refer the suggested model to handle this at the end of the mail. Let me know your thoughts/comments.

2) About Jingrong's questions on "Whether same sub-domain can support different encapsulation types like MPLS and Ethernet" ?
I would think - Yes, a single sub-domain can support many encapsulation types. Architecturally it is possible that, for a sub-domain, each hop can chose the encapsulation to be used based on next-hops capability. Yang model should support it. However, we can discuss and clarify this.

3) A general request to BIER WG is that, we can discuss & progress the yang work at better pace. Traditionally, yang standards progress slowly in IETF resulting in implementation with private yang models :(

Suggested BIER Yang Mode (sd is binded to either ipv4 or ipv6):

   +--rw bier
   |  +--rw bier-global
   |     +--rw default-encapsulation-type?        identityref
   |     +--rw default-bitstringlength?           bsl
   |     +--rw default-bfr-id?                    bfr-id
   |     +--rw default-ipv4-bfr-prefix?           inet:ipv4-prefix
   |     +--rw default-ipv6-bfr-prefix?           inet:ipv6-prefix
   |     +--rw sub-domain* [sub-domain-id] [addr-family]
   |        +--rw sub-domain-id            sub-domain-id
   |        +--rw addr-family            addr-family
   |        +--rw bfr-prefix?  inet:ipv4-ipv6-prefix
   |        +--rw underlay-protocol-type?  underlay-protocol-type
   |        +--rw mt-id?                   mt-id
   |        +--rw bfr-id?                  bfr-id
   |        +--rw bitstringlength?         bsl
   |        +--rw igp-algorithm?           ipa
   |        +--rw bier-algorithm?          Bar
   |        +--rw load-balance-num         uint8
   |        +--rw encapsulation* [bitstringlength]
   |           +--rw bitstringlength               uint16
   |           +--rw encapsulation-type            enum
   |           +--rw max-si?                       rt-type: uint16
   |           +--rw bift-id-base?                 rt-types: bift-id

Thanks,
Senthil

On Mon, Apr 1, 2019 at 12:10 PM Xiejingrong <[e-mail]<mailto:[e-mail]>> wrote:
Hi Chen Ran,

[Ran] "load-balance-number"?Do you means the maximum number of ECMP paths? OSPF YANG data model has defined it .In my opinion, it is neccesarry   to define this item here.

[XJR1]:
Yes I found the load-balance(max-ecmp) configuration in OSPF-yang and ISIS-yang, but I think they are different things, and there should be a load-balance-number  for BIER specifically:

(1)     A BFR may not support BIER ECMP forwarding, while unicast ECMP is supported.

(2)     There may be different number of paths to different BFERs, for example BFER2/BFER2 may have 3/5 paths separately on a BFR, and this BFR  may want a special load-balance-number 15 for better balancing.

[XJR2]:
Second question:
Is it allowed for both IPv4-encapsulation and IPv6-encapsulation being under a single Sub-domain ?

augment /rt:routing:
   +--rw bier
   |  +--rw bier-global
   |     +--rw sub-domain* [sub-domain-id]
   |        +--rw sub-domain-id            sub-domain-id
   |        +--rw underlay-protocol-type?  underlay-protocol-type
   |        +--rw mt-id?                    mt-id
   |        +--rw bfr-id?                   bfr-id
   |        +--rw bitstringlength?          bsl
   |        +--rw igp-algorithm?            ipa
   |        +--rw bier-algorithm?           bar
   |        +--rw af
   |           +--rw ipv4* [bitstringlength bier-mpls-label-base]
   |           |  +--rw bitstringlength               uint16
   |           |  +--rw bier-mpls-label-base          rt-types:mpls-label
   |           |  +--rw max-si?                       max-si
   |           +--rw ipv6* [bitstringlength bier-mpls-label-base]
   |              +--rw bitstrin+--glength            uint16
   |              +--rw bier-mpls-label-base          rt-types:mpls-label
   |              +--rw max-si?                       max-si
   |

The RFC8279 said, a BIER sub-domain must be associated with a single routing underlay (see below). I would understand IPv4 and IPv6 as different  underlay.
   If multiple routing underlays are used in a single BIER domain, each
   BIER sub-domain MUST be associated with a single routing underlay
   (though multiple sub-domains may be associated with the same routing
   underlay).

[XJR3]:
Third question, maybe for the BIER WG.
It may also be helpful to discuss and conclude, if it is allowed for both BIER-MPLS encapsulation and BIER-Ethernet encapsulation being under a single  sub-domain?
I feel it unnecessary since one can use different BIER Sub-domains carrying different encapsulations, and thus an MVPN service using BIER doesn’t  have to specify the encapsulation-type.


From: [e-mail]<mailto:[e-mail]> [mailto:[e-mail]<mailto:[e-mail]>]
Sent: Thursday, September 06, 2018 4:04 PM
To: Xiejingrong <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: Re: Re: [Bier] Comments on draft-ietf-bier-bier-yang


Hi jinrong，

Thanks for your review. Please see inline...



Regards.

Ran


原始邮件
发件人：Xiejingrong <[e-mail]<mailto:[e-mail]>>
收件人：BIER WG <[e-mail]<mailto:[e-mail]>>
抄送人：[e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
日 期 ：2018年07月28日 21:01
主 题 ：Re: [Bier] Comments on draft-ietf-bier-bier-yang
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some more comments:

1.  one sub-domain should allow miltiple {BSL and the according label block}s as encapsulations, see the igp sub-sub-TLV.

[Ran] We will add them ,and  will add the enternet and IPv6 encapsulation type.

2. should the igp-type change to underlay-protocol-type to allow bgp?

[Ran ]will add it.
From:Xiejingrong
To:BIER WG,
Cc:[e-mail]<mailto:[e-mail]>,
Date:2018-07-28 20:36:25
Subject:[Bier] Comments on draft-ietf-bier-bier-yang

Hi folks,

I have the following comments and on draft-ietf-bier-bier-yang.
--should the bier load-balance-number/ipa/bar be added to rt:routing/bier-global/sub-domain (like below)? I think they are some basic items.
 [Ran] "load-balance-number"?Do you means the maximum number of ECMP paths? OSPF YANG data model has defined it .In my opinion, it is neccesarry   to define this item here.
 For the ipa/bar will be added to  rt:routing/bier-global/sub-domain.
augment /rt:routing:
   +--rw bier
   |  +--rw bier-global
   |     +--rw encapsulation-type?   identityref
   |     +--rw bitstringlength?      bsl
   |     +--rw bfr-id?               bfr-id
   |     +--rw ipv4-bfr-prefix?   inet:ipv4-prefix
   |     +--rw ipv6-bfr-prefix?   inet:ipv6-prefix
   |     +--rw sub-domain* [sub-domain-id]
   |        +--rw sub-domain-id      sub-domain-id
   |        +--rw igp-type?          igp-type
   |        +--rw mt-id?             mt-id
   |        +--rw bfr-id?            bfr-id
   |        +--rw bitstringlength?   bsl
   |        +--rw multi-bift-number? load-balance-number
   |        +--rw igp-algorithm?     ipa
   |        +--rw bier-algorithm?    bar

--should the bier-mpls-label-range-size be changed to ‘max si’ or not ? The type is uint8 and thus seems having to change the meaning.
 [Ran] Sure.

Thanks
Jingrong



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