[Capwap] AD review for draft-ietf-capwap-protocol-specification-10.txt
"Romascanu, Dan (Dan)" <dromasca@avaya.com> Wed, 04 June 2008 16:02 UTC
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Thread-Topic: AD review for draft-ietf-capwap-protocol-specification-10.txt
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From: "Romascanu, Dan (Dan)" <dromasca@avaya.com>
To: capwap@frascone.com
Subject: [Capwap] AD review for draft-ietf-capwap-protocol-specification-10.txt
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Here is the AD review of draft-ietf-capwap-protocol-specification-10.txt. Although the document is mature there are a number of places where it can be improved for readability and clarity, and some inconsistencies that should be solved before submitting it to IETF Last Call. I advice to clarify these issues and issue a revised version. I have divided my comments in Technical and Editorial. Technical T1 - a generic comment. In many protocol fields definitions the document lacks max size or max length definitions. I tried but I may have not caught them all. Is the assumption made that for all these fields always the maximum capacity should be reserved? In this case I suggest that a clarification is made in Section 1.2. I prefer however explicit definition of max size and max length whenever needed, as it is not always necessary and wise from a resources point of view to design for max values. T2 - Section 1.1 - Layer 2 and radio technology independence and extensibility seem to me to be major goals of CAPWAP to the same extent as the three goals already mentioned. T3 - Section 2 - 'Protocol Overview' describes the process of discovery and provisioning exchange between the AC and WTP. This seems to be different than the pre-provisioning phase described in Section 12.5. Please clarify and bring this two sections in synch. Also be more clear what parameters are being provisioned in the provisioning exchanged described here. T4 - Section 2.3.1, page 25, Configure to Reset - it is not clear what 'reset the connection' means, this state needs clarification, for example what is the difference / relationship to DTLS teardown T5 - Section 4.3, pag 47 - As I understand the 5 bit field encodes 32 possible wireless bindings (i.e. it's not a bit mask). If true it would be good to make this explicit. My question is whether there is any reason to start with value 1 and not with value 0? Assuming this is already deployed, will 0 be a value to use, or does it have any special significance? T6 - Section 4.3, page 48 - 'This is useful in packets sent from the WTP to the AC, when the native wireless frame format is converted to 802.3 by the WTP.'. Please explain why (is Radio MAC address useful)? Also, s/802.3/IEEE 802.3 format/ T7 - Section 4.3, pag 49 - what is the max size of this Data field in the Wireless specific information. Is it 255 as the length is coded in 8 bit or something else? Please detail. T8 - Session 4.4.1, pag. 50 - what is the max size of the Message Element field? Please detail T9 - Section 4.4.2 - what is the max size of IEEE 802.3 frames that is being supported? Is IEEE 802.3as supported. Please detail T10 - Section 4.5.1.1 - it is not explicitly said whether the CAPWAP control messages in the table at page 54 apply for any wireless technology. If true, why is only a value for IEEE 802.11 mentioned in this specification? In my opinion there is a need to clarify and to take out the IEEE 802.11 value, which should be mentioned in the technology binding document. T11 - Section 4.6 - Please define the CAPWAP Message elements Type Values that are currently TBD T12 - Section 4.6.1 - in the AC Descriptor protocol diagram delete =4 from the Type filed (it can be 4 or 5 as I understand) T13 - Section 4.6.1 - please define the max length of the vendor specific field information T14 - Sections 4.6.2, 4.6.3 - what is the max number of IP addresses on the two lists? T15 - Section 4.6.4, 4,6,5 - what is the max size of the AC names? T16 - the document is not consistent in defining which one of the configuration objects is to be saved in non-volatile memory. For example in 4.6.7 it is mentioned that this message element information is not expected to be saved in non-volatile memory - if this is an exception what is the rule? T17 - Section 4.6.7, 4.6.9 - what is the max length of the MAC address field? (i.e. how many addresses at most on the ACL MAC list?) T18 - Section 4.6.8 - what is the max length of the VLAN Name? As nothing is said I assume the max value currently supported but IEEE 802.1Q but it's better to be specific T19 - Section 4.6.16 - what is the max size of the Data field in the Data transfer Data message? T20 - Section 4.6.16, 4.6.17, 4.6.33, 4.6.36, 4.6.42, 4.6.43 - why do the encoded values start from 1 and not from 0? T21 - Section 4.6.18, 4.6.20 - what is the max number of entries in the array (and thus the max length of the respective MAC Address fields)? T22 - Sections 4.2.24, 4.2.25 - why are the length field defined as >= 12, and >= 24 respectively. Is this triplicate addresses? Or more? And if such cases exist, is this important to detect and report all in one message? T23 - Section 4.6.26 - what is the unit for the Idle timeout T24 - Sections 4.6.27, 4.6.28 - should not these two messages include length of the Value fields? T25 - Section 4.6.29 - what is the max length of the Value field? T26 - Section 4.6.31 - what is the max length of the location field? T27 - Section 4.6.36 - what is the max length of the Message Element field? T28 - Section 4.6.39 - I do not understand the semantics of the value field - what does 'The value associated with the vendor specific element' mean? Is this one byte as the diagram shows, or variable length as indicated by the fact that the length of the message shows >=7? If variable length what is the max length? T29 - Section 4.6.40 - what is the max length of the Optional additional vendor specific WTP board data TLVs? What kind of information is expected to be carried there? The field is not described T30 - Section 4.6.41 - what are the max values of the Value fields? What is the semantics of Other Software version? I do not understand what non-running (firmware) means T31 - Section 4.6.46 - what is the max length of the WTP name field? T32 - Section 4.6.48 - are 16 bits enough to encode the wireless link frame per second. Is an WTP never supposed to exceed 64k frames per second over the air interface? T33 - Sections 4.6.49, 4.6.50 - Do the statistics counters defined here initialize at zero and wrap-up and start counting from start when the max value is reached? This may seem the obvious behavior, but there are other, so clarifying would be useful. It also would be useful to estimate the minimum wrap-up time for each of the counters T34 - Section 4.7.2 - there is no unit specified for the DataChannelKeepAlive timer T35 - section 4.7.14 - this variable is not defined T36 - Section 8.1 - 'The WTP retains the configuration of parameters provided by the AC that are non-default values.' - does this mean that any parameter that has a default value needs not be stored in non-volatile memory, and the WTP will restore the defaults for these parameters on all reset, power-up or bootstrap event? T37 - Section 8.1 - If the WTP opts to save the configuration locally - how is this option selected? Is this a local WTP configurations issue? If so please specify T38 - Section 9 should start with deployment considerations. It looks like there are some assumptions made here about at least an AC being present and configured at deployment, and other such. This should be made clear. T39. Section 13 is insufficient. The recommendation concerning non-configurability of WTPs makes, sense, but what about the ACS? How are ACs configured? It is OK to say that they are configured by proprietary CLI and/or MIB interfaces that will be defined in other CAPWAP document and/or by NETCONF in the future, but something needs to be said. T40 - The same section should include information about impact on network traffic. What is the extra level of traffic that is expected by introducing and deploying CAPWAP? Is there any limit of AC load that needs to be taken into consideration in order to avoid congestion on the network or on the AC? Probably this section should be renamed to also cover Operational considerations, Editorial E1 - In the Abstract section, please eliminate the phrase 'The CAPWAP protocol meets the IETF CAPWAP working group protocol requirements.' or replace it with something that points to a reference less ephemeral than the CAPWAP WG. E2 - A number of editorial problems have been detected when running idnits. Please fix them: ------------------ Checking nits according to http://www.ietf.org/ietf/1id-guidelines.txt: ------------------------------------------------------------------------ ---- == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to http://www.ietf.org/ID-Checklist.html: ------------------------------------------------------------------------ ---- No issues found here. Miscellaneous warnings: ------------------------------------------------------------------------ ---- == Using lowercase 'not' together with uppercase 'MUST' is not an accepted usage according to RFC 2119. Please use 'MUST NOT' (if that is what you mean). Found 'MUST not' in this paragraph: Unless otherwise specified, a control message that lists a set of supported (or expected) message elements MUST not expect the message elements to be in any specific order. The sender MAY include the message elements in any order. Unless otherwise noted, one message element of each type is present in a given control message. Checking references for intended status: Proposed Standard ------------------------------------------------------------------------ ---- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'ChangeCipherSpec' is mentioned on line 1456, but not defined '[ChangeCipherSpec]...' == Unused Reference: 'RFC2132' is defined on line 6048, but no explicit reference was found in the text '[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendo...' ** Obsolete normative reference: RFC 3280 (Obsoleted by RFC 5280) ** Obsolete normative reference: RFC 2434 (Obsoleted by RFC 5226) ** Obsolete normative reference: RFC 1883 (Obsoleted by RFC 2460) -- Unexpected draft version: The latest known version of draft-calhoun-dhc-capwap-ac-option is -00, but you're referring to -02. -- Possible downref: Normative reference to a draft: ref. 'I-D.calhoun-dhc-capwap-ac-option' (No intended status found in state file of draft-calhoun-dhc-capwap-ac-option) == Outdated reference: draft-housley-aaa-key-mgmt has been published as RFC 4962 ---------------------------- E3. Section 1.3 and Informative References The reference for LWAPP is http://www.ietf.org/internet-drafts/draft-ohara-capwap-lwapp-04.txt. Please define an Informative Reference and include a proper [LWAPP] reference in the text The reference for SLAPP is http://www.ietf.org/internet-drafts/draft-narasimhan-ietf-slapp-01.txt. Please define an Informative Reference and include a proper [SLAPP] reference in the text E4. Section 2.1: 'The CAPWAP protocol is independent of a specific WTP radio technology.' My understanding is that CAPWAP is independent not only of the radio technology but also of the layer 2 protocol. I suggest to mention this. E5. First paragraph in Section 2.2 - what 'ideal case' means here? And what 'idealized illustration' means in the last paragraph of the same section? Maybe what is meant is simplified? E6. Please expand DTLS, PSK, EPCGlobal at first occurrence in the text. E7. Section 2.3, page 18, definition of threads - repetition 'figure Figure 3' (three occurrences) E8. Section 2.3, page 18 'Discovery Thread' - 'The state machine transitions in figure 3 are represented by numerals.' - is this true? Are not state transitions like Discovery to Discovery or Discovery to Sulking, etc. represented by special signs, so this should be rather 'represented by discovery and special signs'? E9. Section 2.3, page 24 - the following phrase does not compile well: 'The WTP enters the Image Data state when it receives a successful Join Response message and determines and the included Image Identifier message element is not the same as its currently running image.' E10. Section 2.4.4.3, page 38 - s/a device must have the id-kp-capwapWTP or id-kp-anyExtendedKeyUsage keyPurposeID to act as a WTP/a device MUST have the id-kp-capwapWTP or id-kp-anyExtendedKeyUsage keyPurposeID to act as a WTP E11. Section 3.4 - s/the CAPWAP protocol can be used in any network configuration/the CAPWAP protocol can be used in any network topology including firewall, NAT and middlebox devices/ E12. Section 4.1, page 45 - s/The reason for this header/The reason for this preamble/ E13. Section 4.4.1 - title should be CAPWAP Data Channel Keepalive to be consistent with the rest of the text E14 Section 4.5.2 s/802.1P/802.1Q/ s/precedence value/priority tag/ s/DSCP tag value/DSCP value/ E15. Section 4.7, page 83 - s/This section contains the CAPWAP timers/This section contains the definition of the CAPWAP timers E16 - Sections 4.7.10, 4.7.11, 4.7.12, 4.7.13, 4.7.14 (maybe, not clear what this is, see technical comment), 4.7.15, 4.7.16 are not timers but time-related configuration variables. The name of section 4.7 needs to be changed E17 - Some of the message diagrams are numbered as Figures, some are not. For example the diagram at page 14-15 is not numbered, while the one at page 119 is numbered as Figure 5. Please pick a consistent choice (I prefer numbering) _________________________________________________________________ To unsubscribe or modify your subscription options, please visit: http://lists.frascone.com/mailman/listinfo/capwap Archives: http://lists.frascone.com/pipermail/capwap
- [Capwap] AD review for draft-ietf-capwap-protocol… Romascanu, Dan (Dan)