Re: [spring] WG Last Call for draft-ietf-spring-segment-routing-msdc-02

["Stefano Previdi (sprevidi)" <[e-mail]>]

> On Feb 28, 2017, at 8:29 PM, Anoop Ghanwani <[e-mail]> wrote:
> 
> I support publication of the document as an informational RFC.
> 
> Below are my comments.
> 
> Thanks,
> Anoop
> 
> ==
> 
> - pg 5, line 1
>   What is the criteria that allow sharing the AS number?  Is there a reference?


we changed this to “use the same AS”. As explained in 4.3, using the same AS brings the update loop prevention mechanism so facilitate filtering and propagation.


> - pg 6
>   "This means that every new connection will be established 
>    obliviously (memory- less) with regards to the paths chosen 
>     before, or chosen by other nodes."
>   I am not sure what "chosen by other nodes" adds.  I think it 
>   can be removed. 


It refers to the “obliviousness” extended also to the choices that other nodes of the network could have made.


> - pg 7
>   "local label 1600x" -> "local label (16000 + x).
>   Also because of the way loopbacks are assigned, does this mean that the number nodes that this scheme can handle is 512?  May be good to mention why this is considered a good number.


the example assumes loopbacks assigned from 192.0.2/24. It gives you 255 host addresses. This is of course just illustrative.


> - pg 11
>   "BGP Prefix Segment 16011 then directs the packet down to Node11 along the path (Node5, Node9, Node11)."
>   I think it would be worth mentioning that node 9 need not appear in this path.  In general, because of the nature of clos topologies, there is no need to have intermediate nodes between the spine and the ToR on the way down.  (If there is, it would be good to know why.)


maybe I’m missing your point but the example is baed on the illustrative topology where 9 in the shortest path but you don’t need to specify 9 in the segment list. This is base of SR explained in the architecture draft. 


> 
> Editorial


I fixed the remaining editorial nits.

Thanks.

s.


> 
> - some inconsistencies throughout.  would be good to make them consistent.
>   Node1 and Node2 vs Nodes 1 and 2 vs "Node1" and "Node2"
>   data center, data-center, DC
> 
> - Spell out SRGB and AIGP at first use.
> 
> - pg 1
>   "use-case use-cases" -> use-cases
> 
> - pg 5
>   "via BGP session" -> "via a BGP session."  (missing 'a' and period.)
>   "address of it's loopback" -> "address of its loopback"
>   "per-flow ECMP that does not" -> "per-flow ECMP does not"
>   "placed on one path over others" ->  "placed on one path over others."  (missing period)
>   " implements oblivious" -> "implements an oblivious"
> 
> - pg 6
>   "Absence of path visibility" -> "The absence of path visibility"
>   
> - pg 7
>   "Figure 2 zooms on" -> "Figure 2 zooms in on"
> 
> - pg 8 
>   "an nondeterministic label" -> "a non-deterministic label"
> 
> - pg 9
>   "Referring to Figure 1Referring to Figure 1" -> "Referring to Figure 1"
> 
> - pg 11
>   "if Node7 does not support" -> "even though Node7 does not support"
> 
> - p12
>   Missing a period at the end of the first and second items in Sec 4.3.
>   "Attribute adverting" -> "Attribute advertising"
> 
> - pg 14
>   "let us illustrate this assuming" -> "let us illustrate this concept assuming"
>   "flow to Z" -> "flow to HostZ"
>   "assuming A is made aware" -> "assuming HostA is made aware"
>   
> - pg 15
>   "the latter one" -> "the last one"
> 
> - pg 16
>   "monitoring network elements health" -> "monitoring network elements' health"
>   "inSection 7.2" -> "in Section 7.2"
>   "BGP Labelled Unicast" -> "BGP Labeled Unicast"  (also on pg 17)
> 
> - pg 18
>   "thanks to PHP" -> "because of PHP"
>   "Internet- scale" -> "Internet-scale"  (extra space)
>   "go-to-the- Internet" -> "go-to-the-Internet"
>   " do not recommend to use" -> "do not recommend using"
>   "operation viewpoint" -> "operational viewpoint"
> 
> - pg 19
>   "allows to construct" -> "allows us to construct"
>   "Spine5 and Spine 8" -> Node5 and Node8
>   "(e.g. ToR1's SRGB is [1000, 1999], ToR2's SRGB is [2000, 2999]...)." ->
>   "(e.g. ToR1's SRGB is [1000, 1999], ToR2's SRGB is [2000, 2999], ...)." ->
>