Re: [i2rs] RIB Info/Data model questions: nexthop-id

Hi Sue,

Before I posted the questions, I searched "nexthop-id" in the IM draft and did not find anything definition; then this morning I found the following:

   Nexthops can be identified by an identifier to create a level of
   indirection.  The identifier is set by the RIB manager and returned
   to the external entity on request.

Is the above "identifier" the same as "nexthop-id"? If yes, then it conflicts with your text below?

Jeffrey

From: Susan Hares [mailto:shares@ndzh.com]
Sent: Wednesday, October 07, 2015 8:01 AM
To: Jeffrey (Zhaohui) Zhang <zzhang@juniper.net>; i2rs@ietf.org
Subject: RE: [i2rs] RIB Info/Data model questions: nexthop-id

Jeffrey:

to start this discussion going, I would like to provide you with the answer that was given when the I2RS RIB Information Model was designed.

*        All I2RS RIB information is intended config (see ietf-chairs-netmod-opstate-reqs-01 or ietf-openconfig-netmod-opstat for the definition of intended config),

*        nexthop-id is assigned by the I2RS client, and inserted into the I2RS agent,

*        the I2RS agent installs the I2RS RIB ephemeral state, and provides back status (installed, not installed).

nexthop id  allows for all types of next hops (chains, inet-v4, inet-v6, mac-address, interface tunnels) to be indicated  with a single id that can be directly accessed.  This allows these different types of next-hop to be directly referenced with the nexthop-id.

As to protection,  Let's base our discussion on I2RS RIB IM p. 19 (see below)

The protection id - identifies of preference, nexthop-id.  Preference ID identifies the tuple.   You might have multiple tuples with a nexthop-id.

Protection-id 1:  preference=10, nexthop-id=1

Protection-id 2:  preference = 2, nexthop-id=1

Protection-id 3:  preference=1, nexthop-id = 1

Protection-id 4: preference =1, nexthop-id=2

I do not understand how the protection-id should be linked by nexthop.

Sue

======================

I2RS RIB IM p. 19 for your reference:

----------------------------

<nexthop> ::= <NEXTHOP_PROTECTION> <1> <interface-primary>
                                   <2> <interface-backup>)

Derived as follows:

<nexthop> ::= <nexthop-protection>

<nexthop> ::= <NEXTHOP_PROTECTION> (<NEXTHOP_PREFERENCE> <nexthop>

                      (<NEXTHOP_PREFERENCE> <nexthop>)...)

<nexthop> ::= <NEXTHOP_PROTECTION> (<NEXTHOP_PREFERENCE> <nexthop>

                      (<NEXTHOP_PREFERENCE> <nexthop>))

<nexthop> ::= <NEXTHOP_PROTECTION> ((<NEXTHOP_PREFERENCE> <nexthop-base>

                      (<NEXTHOP_PREFERENCE> <nexthop-base>))

<nexthop> ::= <NEXTHOP_PROTECTION> (<1> <interface-primary>

                      (<2> <interface-backup>))

Traffic can be load-balanced among multiple primary nexthops and a

single backup.  In such a case, the nexthop will look like:

   <nexthop> ::= <NEXTHOP_PROTECTION> (<1>

                 (<NEXTHOP_LOAD_BALANCE>

                  (<NEXTHOP_LB_WEIGHT> <nexthop-base>

                  (<NEXTHOP_LB_WEIGHT> <nexthop-base>) ...))

                   <2> <nexthop-base>)

-----Original Message-----
From: i2rs [mailto:i2rs-bounces@ietf.org] On Behalf Of Jeffrey (Zhaohui) Zhang
Sent: Monday, October 05, 2015 9:59 AM
To: i2rs@ietf.org<mailto:i2rs@ietf.org>
Subject: [i2rs] RIB Info/Data model questions: nexthop-id

Hi,

Both the RIB info and data model mentions nexthop-id, but neither specifies who manages/assigns the ID. Can the specs point that out?

It seems that it could be both ways - the IDs could be allocated by routers (servers) or could be allocated by clients. Different ID spaces would be used depending on who allocates the IDs.

Related to the above, a specific question on the data model:

  grouping nexthop {

    leaf nexthop-id {

      mandatory true;

      type uint32;

    }

    choice nexthop-type {

       ...

       case nexthop-protection {

        list nexthop-protection-list {

            key "nexthop-protection-id";

            leaf nexthop-protection-id {

              mandatory true;

              type uint32;

            }

           leaf nexthop-preference {

             ...

           }

           leaf nexthop {

             mandatory true;

             type nexthop-ref;

           }

        }

      }

Here a nexthop-protection is a list. Being a list it requires a key and we defined this uint32 nexthop-protection-id, which I assume the controller needs to assign and both the controller and the router needs to remember. The list entry has a member "nexthop" which is a nexthop-ref, which is a nexthop-id:

  typedef nexthop-ref {

    type leafref {

      path  "/i2rs-rib:routing-instance/i2rs-rib:rib-list" +

            "/i2rs-rib:route-list/i2rs-rib:nexthop/i2rs-rib:nexthop-id";

    }

  }

So - why can't we use the nexthop-id itself as the key?

Thanks.

Jeffrey

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