Subject: Re: [i2rs] Any feedback on the Protocol Independent Flow Security Policies exchanged over I2NSF service layer interface?

From: Linda Dunbar <[email-masked]>
Date: Mon, 13 Jun 2016 21:24:38 +0000

Christian,

Thank you very much for the feedback.

Agree 100% of what you said:
Using BGP FS to exchange flow-based security policy information between domains is probably one of the most attractive approaches, but I assume this information will have to comply with BGP FS encoding schemes, whether the corresponding policy is described in a NETCONF/YANG data model or not. So, I think it's fair to state that, whatever the semantics of the (flow-based) security policy data model, corresponding information may be exchanged between domains and formatted according to the protocol used to carry such information between domains. It seems to me that both considerations are orthogonal.

The reason that BGP FlowSpec is mentioned here is:

-        To emphasize the different aspects that I2NSF is to tackle:  the comprehensive Flow Security Policies data model (that are not constrained to the BGP encoding scheme). For example, if used between "domains", one domain inquiry of "flow security policies" capability of other domain is a very important part. The actual flow polices from one domain to another is only part of the game.

It is really good that you brought this up: "inter-domain QoS policy enforcement remains very hard to achieve"

The Inter-Domain Flow Security Policy are different in the following aspects:

-         the I2NSF Flow Security Policy, (i.e. over the I2NSF Service Layer Interface), are inquired and set by each domain's management system (or domain's controllers). There have be authentication, authorization and billing process involved for one domain management system to grant the requests from other domain's management systems.

-        Whereas the QoS mechanism (as being carried by encoding in data packets), It is difficult for forwarding devices from one domain to take actions (that requires its own $$$ resources) based on bits set by other domains.

Thanks,

Linda
From: [email-masked] [mailto:[email-masked]]
Sent: Monday, June 13, 2016 11:23 AM
To: Linda Dunbar; BOUCADAIR Mohamed IMT/OLN
Subject: RE: Any feedback on the Protocol Independent Flow Security Policies exchanged over I2NSF service layer interface?

Hello Linda,

A few preliminary comments from my side, based upon the enclosed text below (I didn't read the draft yet).

[snip]

As BGP Flow Specification [exchanged among BGP peers] can been deployed to achieve DDoS mitigation, the Flow Security Policy setting from one domain to another domain is protocol independent.
[CJ] I don't understand the above causality effect, since BGP FS is explicitly mentioned. As a matter of fact, I think policies (whatever their nature) are protocol-independent by nature, as implicitly indicated in the definition reminded in the supa WG charter<https://datatracker.ietf.org/wg/supa/charter/>, for example.
 I2NSF focuses on the information/data models, allowing domains using NETCONF or RESTCONF to exchange capability and set up the flow security policies.
[CJ] Right, but again, information and data models can rely upon various semantics - YANG, but also SMI, SPPI, etc. Using BGP FS to exchange flow-based security policy information between domains is probably one of the most attractive approaches, but I assume this information will have to comply with BGP FS encoding schemes, whether the corresponding policy is described in a NETCONF/YANG data model or not. So, I think it's fair to state that, whatever the semantics of the (flow-based) security policy data model, corresponding information may be exchanged between domains and formatted according to the protocol used to carry such information between domains. It seems to me that both considerations are orthogonal.

"Protocol Independent Flow Security Policies" is for one domain (A) to request another domain (B) to enforce the desired policies for flows destined towards the Domain A. This can be an effective way for Domain A to prevent the unwanted attacks (e.g. DDoS)  from even occupying its links/ports connected to the Domain B.

BGP flow specification is configured in the BGP peers, whereas the I2NSF Protocol Independent Flow Security Policies"  are exchanged between domains,
[CJ] Why not simply state "flow-based security policy information"? Besides, the above wording suggests the whole security policy information is supposed to be exchanged between domains, which I think is debatable. Also, exchanging policy information between domains raises consistency and security issues: this is why inter-domain QoS policy enforcement remains very hard to achieve for example.
which can be
Enterprise domain <-> Provider domain, Overlay <-> Underlay, Cloud provider <-> Underlay.

Enterprise can have its own DDoS mitigation tools, but those internal DDoS mitigation tools can't effectively prevent the DoS attacks that saturate the access ports and links between Enterprise and the providers.
[CJ] Right, but one would argue this is the responsibility of the service provider to prevent any attack that may saturate access resources that connect the enterprise customer to the network operated by the service provider. That is, why would internal mitigation tools be considered anyway?

Same goes for Overlay networks.

Very often, the paths (or links) among nodes of a overlay network are provided by other network operators (a.k.a. "underlay network").  Very much like traditional networks placing FW (Firewall) or IPS (Intrusion Prevention System) on the wire to enforce the flow security rules, I2NSF Protocol Independent Flow Security Policies can be used by overlay networks to request certain flow based security rules to be enforced by its underlay networks, to prevent the unwanted attacks traffic from occupying the physical links and ports to the overlay network nodes, and to avoid the overlay nodes' CPU/Storage/Port utilization being consumed down by the various attacks.  Here is one example of "Overlay Video Communication network" exchange Flow Policies to the Underlay network.

[CJ] The above example clearly shows the necessary interaction between the two PDPs/controllers, to make sure that decisions made by the network controller accommodate the needs of the video customer as possibly expressed towards the video controller: for example, customer demands that the confidentiality of the videoconference needs to be preserved, thereby suggesting the use of the IPsec protocol suite. The video controller may enforce an IPsec design based upon the transport mode, whereas the network controller is solicited to allocate IPsec resources (read for example no AH, ESP in NULL mode) accordingly. This may possibly raise conflicting configuration tasks (the video controller uses AH, the network controller doesn't), thereby leading to inconsistency that may jeopardize the service. Whether BGP FS is used to carry security policy information between the two controllers is hardly the point, imho: what matters is the consistency of the (flow-based security policies enforced by both parties, and which should be derived from the customer's requirements (if any).
The goal of I2NSF is to specify the common information model and data model for the  Protocol Independent Flow Security Policies which can be queried and set between domains.
[CJ] OK.

https://datatracker.ietf.org/doc/draft-fang-i2nsf-inter-cloud-ddos-mitigation-api/ is just the starting point. (needs more work to improve the clarity). We are asking if people to express their opinion on this work to the [email-masked]<mailto:[email-masked]> list.
[CJ] I need to read this draft and will get back to you accordingly, but this may take a couple of weeks as I'm pretty busy for the time being.

I'll let Med further comment as appropriate.

Cheers,

Christian.

Thanks, Linda

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