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
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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