Re: [secdir] SECDIR review of draft-ietf-l2vpn-vpls-inter-domain-redundancy-05
Stephen Kent <kent@bbn.com> Thu, 17 April 2014 13:55 UTC
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Date: Thu, 17 Apr 2014 09:55:27 -0400
From: Stephen Kent <kent@bbn.com>
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To: Lizhong Jin <lizho.jin@gmail.com>, 'secdir' <secdir@ietf.org>, zhliu@gsta.com, chen.ran@zte.com.cn, dcai@cisco.com, ssalam@cisco.com, 'Adrian Farrel' <adrian@olddog.co.uk>, giheron@cisco.com, nabil.n.bitar@verizon.com
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Subject: Re: [secdir] SECDIR review of draft-ietf-l2vpn-vpls-inter-domain-redundancy-05
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Lizhong, Thanks for the quick reply. > > Hi Stephen, > > Thank you for the detail review. See my reply inline below. > > Regards > > Lizhong > > *From:*Stephen Kent [mailto:kent@bbn.com] > *Sent:* Wednesday, April 16, 2014 5:05 AM > *To:* secdir; zhliu@gsta.com; lizho.jin@gmail.com; > chen.ran@zte.com.cn; dcai@cisco.com; ssalam@cisco.com; Adrian Farrel; > giheron@cisco.com; nabil.n.bitar@verizon.com > *Subject:* SECDIR review of > draft-ietf-l2vpn-vpls-inter-domain-redundancy-05 > > I reviewed this document as part of the security directorate's ongoing > effort to review all IETF documents being processed by the IESG. > These comments were written primarily for the benefit of the security > area directors. Document editors and WG chairs should treat these > comments just like any other last call comments. > > This is a very brief document, just 12 pages. The Abstract for this > document, n its entirety, says: "In many existing Virtual Private LAN > Service (VPLS) deployments based on RFC 4762, inter-domain > connectivity has been deployed without node redundancy, or with node > redundancy in a single domain. This document describes a solution for > inter-domain VPLS based on RFC 4762 with node and link redundancy in > both domains." > > Unfortunately, this confusing wording is typical of the writing in > several areas of this document. The RFC Editor will need to work > closely with the authors to make this document easier to read. Also, > there are several instances of acronyms used without expansion (e.g., > ASBR), making reading even harder. > > [Lizhong] I try to rephrase the abstract below to make it more clear. > I will check again for the acronyms in detail. BTW, the ASBR has been > expanded in section 3 line 193. > The first use of ASBR is before then, I believe. The convention is to expand an acronym on first use. > > In many existing RFC 4762 based Virtual Private LAN Service (VPLS) > inter-domain deployments, the pseudowire (PW) connectivity has been > deployed without node redundancy, or with node redundancy only in a > single domain. That will take high risk of service interruption, since > at least one domain will not have PW node redundancy. This document > describes a inter-domain VPLS solution which could provide PW node > redundancy in both domains. > I think it would be clearer to say: In many existing Virtual Private LAN Service (VPLS) inter-domain deployments (based on RFC 4762), pseudowire (PW) connectivity offers no node redundancy, or offers node redundancy only with a single domain. This deployment approach incurs a high risk of service interruption, since at least one domain will not offer PW node redundancy. This document describes an inter-domain VPLS solution that provides PW node redundancy across domains. > > I like the fact that the document includes a "Motivation" section. It > provided a good description of why a new approach to achieving > redundancy in the VPLS context is needed. > > Section 5 ends with a curious statement: > > There are two PW redundancy modes defined in [RFC6870]: > > Independent mode and Master/Slave mode. For the inter- > > domain four-PW scenario, it is required for PEs to ensure > > that the same mode is supported on the two ICCP peers in > > the same RG. One method to ensure mode consistency is by > > manual operation. Other methods are also possible and are > > out of the scope of this document. > > This says that two ASes have to ensure that both employ the same > redundancy mode choice, notes that they can verify this manually, and > that says there are other options to meet this requirement, but > provides no description of the other options. Not very useful. > > [Lizhong] I think the text is OK. If you insist, I could remove. > the text is not OK, because its states that there are multiple ways to ensure consistency, but identifies only one. > > ... > > Section 5.3 describes switchover operation in the more complex four PW > cases. It contains some RFC 2119 key words, but there are several > instances of lowercase "should". Is this intentional? > > [Lizhong] I will check again, some is intentional, but some is not. > If you are defining rules for how to achieve switchover, use of non-normative text is not of much value. > > The Security Considerations section is brief, only 4 short > paragraphs. It cites the Security Considerations sections of RFCs > 4762 and 6870, plus the I-D (draft-ietf-pwe3-iccp) that forms the > basis of part of the solution described here. > > RFC 4762 also contains a brief Security Considerations section, > referring the reader to RFC 4111, the PPVPN Security Framework. That > document discusses security in detail, although most of the discussion > does not appear to be directly applicable to the redundancy mechanisms > of this document. > > RFC 6870 is directly relevant. It contains a two-sentence Security > Considerations section (almost a record for brevity?) with a lowercase > "must" for emphasis? This section refers to RFC 4447, which contains a > meaningful SC section (finally). That document mandates use of the > TCP/MD5 option for LDP. This is almost consistent with the second > paragraph of the SC section in this document (which weakens this to a > MAY), but not with the third paragraph (which seems to call for TCP-AO). > > [Lizhong] RFC6870 SC is only valid for PW control plane. The second, > third and fourth paragraph is described for ICCP control plane. I will > make that clear in the text. > OK. > > ... > > [Lizhong] thank you for the comments. I tend to remove the conflict > parts with [I-D.ietf-pwe3-iccp], and only describe the new security > considerations. Please help to review the following text: > > Besides the security properties of [I-D.ietf-pwe3-iccp] for ICCP > control plane, [RFC4762] and [RFC6870] for PW control plane, this > document will have additional security consideration for ICCP control > plane. > > In this document, ICCP protocol is deployed between two PEs or ASBRs. > The two PEs or ASBRs should only be connected by a well managed and > highly monitored network. This should be ensured by the operator. > > The state flapping on the inter-domain and intra-domain pseudowire may > cause security threats or be exploited to create denial of service > attacks. For example, excessive pseudowire state flapping (e.g., by > malicious peer PE's implementation) may lead to excessive ICCP > exchanges. Implementations SHOULD provide mechanisms to perform > control-plane policing and mitigate such types of attacks. > This is clearer. Steve
- [secdir] SECDIR review of draft-ietf-l2vpn-vpls-i… Stephen Kent
- Re: [secdir] SECDIR review of draft-ietf-l2vpn-vp… Lizhong Jin
- Re: [secdir] SECDIR review of draft-ietf-l2vpn-vp… Stephen Kent
- Re: [secdir] SECDIR review of draft-ietf-l2vpn-vp… Adrian Farrel
- Re: [secdir] SECDIR review of draft-ietf-l2vpn-vp… Lizhong Jin
- Re: [secdir] SECDIR review of draft-ietf-l2vpn-vp… Lizhong Jin
- Re: [secdir] SECDIR review of draft-ietf-l2vpn-vp… Lizhong Jin
- Re: [secdir] SECDIR review of draft-ietf-l2vpn-vp… Stephen Kent