Re: [Lwip] Early chair review of Neighbor Management Policy for 6LoWPAN
Rahul Jadhav <rahul.ietf@gmail.com> Fri, 06 July 2018 13:44 UTC
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From: Rahul Jadhav <rahul.ietf@gmail.com>
Date: Fri, 06 Jul 2018 19:14:25 +0530
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To: Mohit Sethi <mohit.m.sethi@ericsson.com>
Cc: lwip@ietf.org, draft-ietf-lwig-nbr-mgmt-policy@ietf.org
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Subject: Re: [Lwip] Early chair review of Neighbor Management Policy for 6LoWPAN
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Thank you Mohit for the review. This helps a lot. We ll update the draft and provide the detailed response soon. Thanks, Rahul On Thu, 5 Jul 2018 at 15:11, Mohit Sethi <mohit.m.sethi@ericsson.com> wrote: > > Hi Rahul and co-authors, > > Here is my early chair review of the Neighbor Management Policy draft. I > believe that more work is needed to improve the document going forward. > > - The document currently needs more text on what kind of networks is the > suggested neighbor management policy suitable for. Does it work equally > well in networks with static nodes and networks with mobile nodes? What > kind of resource-constrained devices are considered in this document? > For example, what kind of processor, memory and energy-resources are > available on devices considered in this document. > > - The document uses so many acronyms without expanding them even once. > For example NDP/DAO/NS/NA are never expanded or explained. It would make > sense to add these to the terminology section 1.1. While it is > reasonable to assume that the reader has some background in 6lowpan > networks, it would not hurt to explain what these messages are used for. > Please also state in the Introduction section that the reader is assumed > to be familiar with 6lo and RPL networks. > > - The abstract could be re-phrased and expanded. Here is a suggestion: > This document describes the problems associated with neighbor cache > management in multihop networks involving resource-constrained devices. > Thereafter, it also presents a sample neighbor management policy that > allows efficient cache management in multihop networks of > resource-constrained devices. (Possible add info on what kind of > networks is this neighbor management policy suitable for) > > - The document defines node density as maximum number of devices > connected on a single hop? This needs to be more precise. Would it be > right to say: node density is the "maximum number of nodes that are > reachable with a single hop from any given node in the network". > > - What is typical neighbor cache size in devices being considered. Is it > 4 nodes/8 nodes? For an average reader who hasn't deployed a 6lo > network, it is hard to judge. I guess it would depend on the type of > platform and available resources on the device. > > - The document says that FCFS (First Come First Server) and LRU (Least > Recently Used) don't always result in efficient cache entry management. > However, they are also easy to implement in practice. Any smarter > management policy would likely result in more lines of code? Since you > have implementation, it would be good to document some experience from > that here. > > - It is currently hard to understand Figure 2 and 3. It refers to "New". > Perhaps rename it to "New node"/"New joining node". Isn't the new node > that is joining an existing network also the PaC (PANA Client). Perhaps > it would help to say that in the text. What is the message PCI in figure > 2. It is not explained anywhere in text. > > - The neighbor management policy presented in this document is > independent from the credentials used for authentication over PANA. > However, it would still help the reader if you mention the credentials > used in your deployment and how many round-trips are necessary for the > AUTHPROC shown in Figure 2 to complete. Currently, it looks like that > the AUTHPROC is a single message? > > - The current text says "The node selects one or more of its neighboring > peer as its preferred parent based on the DIO received from these > peers". What logic does it use when picking one peer over the others? > > - The current text says "The child node may send a secure unicast NS > with ARO option containing its global address to be registered on the > parent node." Perhaps it would help to give more context here. What keys > are used for the secured unicast NS message. Did they result from the > initial authentication over PANA. > > - The section on NCE Deletion is easy to understand and makes sense. > Thanks for that. > > - In Section 3, the text says "As shown in the figure, the neighbor > cache is partitioned into different entry types.". Please use the figure > label, As shown in figure 5, the neighbor cache..... > > - There is no explanation for the counters in Table 1: > MAX_ROUTING_PARENT_NCE_NUM, MAX_ROUTING_CHILD_NCE_NUM, > MAX_OTHER_NCE_NUM. Is it the maximum cache entries that a node can store > or the cache entries currently available? > > - The proactive approach wherein the parent node signals its > resource-availability in DIO message. How does this signaling work? > There is no information in the draft? Does it use the flags or DIO > options such as "0x03 Routing Information" specified in RFC 6550. > Remember, the document is informational, so we should not be > standardizing new message formats here. > > - The security considerations sections needs some organization. The text > "Only a subset of entries are reserved for un-authenticated nodes" is > repeated. Isn't there an inherent assumption that after authentication, > all the nodes are expected to behave as honest. Otherwise misbehaving > nodes could always advertise that they don't have any cache entries > remaining. If so, it might be worth writing some text around this. > > - There were some grammar issues but we can fix them after the issues I > raised above are addressed. Overall, the document provides useful > guidance but more work is needed to improve its readability and more > precise text is needed for a developer to implement neighbor management > policy presented here. > > --Mohit >
- Re: [Lwip] Early chair review of Neighbor Managem… Rahul Jadhav
- [Lwip] Early chair review of Neighbor Management … Mohit Sethi
- Re: [Lwip] Early chair review of Neighbor Managem… Rahul Jadhav