Re: [I2nsf] I-D Action: draft-ietf-i2nsf-sdn-ipsec-flow-protection-05.txt

"Valery Smyslov" <> Thu, 25 July 2019 16:00 UTC

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From: "Valery Smyslov" <>
To: "'Rafa Marin Lopez'" <>
Cc: =?utf-8?Q?'Fernando_Pere=C3=B1=C3=ADguez_Garc=C3=ADa'?= <>, =?utf-8?Q?'Martin_Bj=C3=B6rklund'?= <>, <>, "'Gabriel Lopez'" <>, "'Yoav Nir'" <>, <>
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Subject: Re: [I2nsf] I-D Action: draft-ietf-i2nsf-sdn-ipsec-flow-protection-05.txt
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Hi Rafa,


thank you for adding this text. I think these are the very minimum

recommendations that are needed to help implementers to handle various 

error cases correctly.





From: Rafa Marin Lopez <> 
Sent: Thursday, July 25, 2019 5:54 PM
To: Valery Smyslov <>
Cc: Rafa Marin Lopez <>es>; Fernando Pereñíguez García <>es>; Martin Björklund <>om>;; Gabriel Lopez <>es>; Yoav Nir <>om>; WG <>
Subject: Re: [I2nsf] I-D Action: draft-ietf-i2nsf-sdn-ipsec-flow-protection-05.txt


Hi Valery:


Great!. Thanks for these comments. Very valuable. Following your suggestion we would like to add similar text to part of the I-D describing the process of IPsec SA installation. This is inline with the previous text about rekeying we sent:



"Figure 4 describes the IKE-less case, when a data packet needs to be

protected in the path between the NSF A and NSF B:


   1.  The administrator establishes the flow-based security policies,

       and the Security Controller looks for the involved NSFs.


   2.  The Security Controller translates the flow-based security

       policies into IPsec SPD and SAD entries.


   3.  The Security Controller inserts these entries in both NSF A and

       NSF B IPsec databases (SPD and SAD).  The following text

       describes how this happens between two NSFs A and B:


       *  The Security Controller chooses two random values as SPIs: for

          example, SPIa1 for NSF A and SPIb1 for NSF B.  These numbers

          MUST not be in conflict with any IPsec SA in NSF A or NSF B.

          It also generates fresh cryptographic material for the new

          inbound/outbound IPsec SAs and their parameters and send

          simultaneously the new inbound IPsec SA with SPIa1 and new

          outbound IPsec SAs with SPIb1 to NSF A; and the new inbound

          IPsec SA with SPIb1 and new outbound IPsec SAs with SPIa1 to

          B, together with the corresponding IPsec policies.


       *  Once the Security Controller receives confirmation from NSF A

          and NSF B, the controller knows that the IPsec SAs are

          correctly installed and ready.


       If some of the operations described above fails (e.g. the NSF A

       reports an error when the Security Controller is trying to

       install the SPD entry, the new inbound and outbound IPsec SAs)

       the Security Controller must perform rollback operations by

       deleting any new inbound or outbound SA and SPD entry that had

       been successfully installed in any of the NSFs (e.g NSF B) and

       stop the process (NOTE: the Security Controller may retry several

       times before giving up).  Other alternative to this operation is:

       the Security Controller sends first the IPsec policies and new

       inbound IPsec SAs to A and B and once it obtains a successful

       confirmation of these operations from NSF A and NSF B, it

       proceeds with installing to the new outbound IPsec SAs.  However,

       this may increase the latency to complete the process.  As an

       advantage, no traffic is sent over the network until the IPsec

       SAs are completely operative.  In any case other alternatives may

       be possible.  Finally, it is worth mentioning that the Security

       Controller associates a lifetime to the new IPsec SAs.  When this

       lifetime expires, the NSF will send a sadb-expire notification to

       the Security Controller in order to start the rekeying process.


   4.  The flow is protected with the IPsec SA established by the

       Security Controller.



We have also clarified proactive and reactive and the operations associated in a text below


"Instead of installing IPsec policies in the SPD and IPsec

SAs in the SAD in step 3 (proactive mode), it is also

possible that the Security Controller only installs the SPD

entries in step 3 (reactive mode). In such a case, when a

data packet requires to be protected with IPsec, the NSF

that saw first the data packet will send a sadb-acquire

notification that informs the Security Controller that needs

SAD entries with the IPsec SAs to process the data

packet. In such as reactive mode, since IPsec policies are

already installed in the SPD, the Security Controller

installs first the new IPsec SAs in NSF A and B with the

operations described in step 3 but without sending any IPsec

policies. Again, if some of the operations installing 

the new inbound/outbound IPsec SAs fail, 

the Security Controller stops the process and performs a

rollback operation by deleting any new inbound/outbound SAs                         

that had been successfully installed.”


We hope this text also helps.


Thank you very much again.


El 23 jul 2019, a las 12:31, Valery Smyslov < <> > escribió:


Hi Rafa,



Hi Valery:

El 22 jul 2019, a las 18:07, Valery Smyslov < <>> escribió:


Hi Yoav,


I think that it is not the performance of the SC that would matter,

but the possible delays in the network. If we think of the network

connecting the SC and the NSFs as of one close to "ideal", then we have

no problems. Otherwise the SC must be prepared to deal with 

network issues. Note, that in case of reactive SA setup and in case

of rekeying the SC must manage two NSFs in a synchronized manner,

and any of these NSF can go offline or reboot or stop responding

during this, and SC must properly deal with all this events,

making proper roll-back on the other NSF.


Regarding this: steps 1, 2 and 3 in section 5.3.1 are lock-step. As you may see we mention: 


"Once the Security Controller receives confirmation from A and B, the controller knows that the inbound 

IPsec A are correctly installed.”


Having said this. Maybe this text after the description of steps 1, 2 and 3 may help:


“If some of the operations in step 1 fails (e.g. the NSF1 reports an error when the Security Controller is trying to install anew new inbound IPsec SA) the Security Controller must perform rollback operations by removing any new inbound SA that had been successfully installed during step 1. 


If step 1 is successful but some of the operations in step 2 fails (e.g. the NSF1 reports an error when the Security Controller is trying to install the new outbound IPsec SA), the Security Controller must perform a rollback operation by deleting any new outbound SA that had been successfully installed during step 2 and by deleting the inbound SAs created in step 1. 


If the steps 1 an 2 are successful and the step 3 fails the Security Controller will avoid any rollback of the operations carried out in step 1 and step 2 since new and valid IPsec SAs were created and are functional. The Security Controller may reattempt to remove the old inbound and outbound SAs in NSF1 and NSF2 several times until it receives a success or it gives up. In the last case, the old IPsec SAs will be removed when the hard lifetime is reached." 


          Yes, this text would help.


          Thank you,



Btw, you can also find some text about NSF state loss in section 5.3.2. 


With IKE case RFC7296 contains very specific advices what

to do in case of packet loss, delay etc (e.g in case of 

simultaneous rekeying). I'd like to see the same advices

for SC's behavior in case of network issues.








Hi, Valery


Obviously, you need a security controller that scales to the number of SAs it needs to generate. But generating an SA in the IKE-less case is just generating 72 random bytes (for AES-GCM-256) and packaging them.  I don’t think with a properly scaled SC this would produce more latency than IKE between the nodes, which has 1/2 round-trips and requires asymmetric operations.


On 22 Jul 2019, at 11:39, Valery Smyslov < <>> wrote:


Hi Rafa,


sure this problem is general for any SDN solution.

My point was that if SC performs a lot of real-time 

(or near real-time) tasks as it may happen in IKE-less case, 

then this problem may become serious.


Anyway, I'm happy with the updated text, thank you.

However, in a following document(s), suggested by Yoav,

I'd like to see more concrete advices of how SC should

act in this situation to ensure that the consistence of the 

network is preserved despite all the possible delays etc.






From: Rafa Marin Lopez < <>> 
Sent: Monday, July 22, 2019 6:11 PM
To: Valery Smyslov < <>>
Cc: Rafa Marin Lopez < <>>gt;; Yoav Nir < <>>gt;;  <>;  <>; Fernando Pereñíguez García < <>>gt;;  <>; Gabriel Lopez < <>>
Subject: Re: [I2nsf] I-D Action: draft-ietf-i2nsf-sdn-ipsec-flow-protection-05.txt


Hi Valery:


Thank you very much for your comments. Please see ours inside.

El 20 jul 2019, a las 16:38, Valery Smyslov < <>> escribió:




thank you for updating the document. I still think that some aspect

of IKE-less use case are not discussed yet (well, probably they are not 

"serious", depending on one's definition of "serious").


Unlike IKE case. which we can consider as mostly static configuration,

the IKE-less case is a dynamic one. If IPsec SA are being created 

on demand (via kernel-acquire) and the traffic volume is high,

then depending on the IPsec policy IKE-less case can become 

a highly dynamic, which implies additional requirement on both

the network connecting SC and NSF and the performance of the protocol used to 

secure their communications. In other words, in IKE case the communication

between IKE daemon and kernel is seamless, while in IKE-less

case the communication between NSF ("kernel") and SC adds

noticeable delay (and can potentially add quite a long delay),

which can influence total performance of the system.


Generally IKE-less case requires more communications between

different nodes to establish or rekey IPsec SA, than IKE case

(I assume that IKE SA is already established), that may have

an impact on high-speed networks with short-lived IPsec SAs,

especially if they are created per transport connection

(say one IPsec SA for one TCP session).


[Authors] What you have just described is what happens in any SDN-based network. In fact, your comment would be applicable to practically any scenario based on the SDN paradigm. In the particular case of the I-D, the IKE-less case is the most similar to case you can see in, for example, Openflow networks where latency is also important (just as an example :  <> )


I believe, that SC's task of managing IPsec SAs in IKE-less case 

may become quite complex, especially because due to the

additional delay, introduced by the network, the picture of the

state of the SAs the SC has can become inaccurate (well, 

it will always be inaccurate, but with short delays it doesn't matter).

Just an example. Consider an SC receives a signal from NSF that an SA

is soft expired and starts rekeying process by first installing a new

pair of inbound SAs. It successfully installs them on the NSF

it receives notification from, but then it receives a notification

that the other NSF has rebooted, so it must clear all the SAs on

its peers, including the just installed new one (which is only

half-done). There seems to be a lot of nuances, and the document 

completely ignores them. Not that I think that the task

is impossible, but the algorithm of managing the SAs can become

quite complex and possibly unreliable.


[Authors] We largely thought about this kind of cases, although we do not see any different that may happen in SDN-based network nowadays. And it seems to me that SDN is becoming something generally accepted despite the different nuances that needs to be consider. In any case, what you mention is not ignored in our document because it is included in the text we have in section 5.3 (see below) where we highlight the complexity is shifted to the SC (that’s clear). But as I mentioned, this is not specific to IKE-less case but for any solution based on the pure SDN paradigm (such as Openflow networks). In other words, the cases you well mention are applicable to any SDN-based solution.


I didn't find this discussion in the draft (sorry if I missed it).


Your comments are somehow summarized in the following text section 5.3


"On the contrary, the overload of creating fresh IPsec
   SAs is shifted to the Security Controller since IKEv2 is not in the
   NSF.  As a consequence, this may result in a more complex
   implementation in the controller side.  This overload may create some
   scalability issues when the number of NSFs is high.

In general, literature around SDN-based network management using a

   centralized Security Controller is aware about scalability issues and

   solutions have been already provided (e.g. hierarchical Security

   Controllers; having multiple replicated Security Controllers, etc)."


I would add that a high-speed dedicated management network between the SC and the NSFs can be also in place to even limit reduce these delays between the SC and NSFs (this idea comes again from Openflow networks). Also the SC can select more “intelligent” lifetime to orchestrate better when the notifications may appear.


In any case, we think we can improve that text as follows: 


"On the contrary, the overload of creating and managing IPsec

   SAs is shifted to the Security Controller since IKEv2 is not in the
   NSF. As a consequence, this may result in a more complex
   implementation in the controller side in comparison with

   IKE case.  For example, the Security Controller have to deal with 

   the latency existing in the path between the Security Controller 

   and the NSF in order to solve tasks such as, rekey or creation and 

   installation of new IPsec SAs. However, this is not specific to our 

   contribution but a general aspect in any SDN-based network. 

   In summary, this overload may create some scalability and performance 

   issues when the number of NSFs is high.

   Nevertheless, literature around SDN-based network management using a
   centralized Security Controller is aware about scalability and
   performance issues and solutions have been already provided and
   discussed (e.g.  hierarchical Security Controllers; having multiple
   replicated Security Controllers, dedicated high-speed management
   networks, etc). In the context of SDN-based IPsec management, one

   way to reduce the latency and alleviate some performance issues can

   be the installation of the IPsec policies and IPsec SAs at the same time

   (proactive mode, as described in Section 7.1) instead of waiting for

   notifications (e.g. a notification sadb-acquire when a new IPsec SA 

   is required) to proceed with the IPsec SA installations (reactive mode). 

   Another way to reduce the overhead and the potential scalability and

   performance issues in the Security Controller is to apply the IKE
   case described in this document, since the IPsec SAs are managed
   between NSFs without the involvement of the Security Controller at
   all, except by the initial IKE configuration provided by the Security


Please see also our comments to Yoav.


Best Regards.








Thanks for getting this done and published.


We will wait with requesting publication until the I2NSF session next week.  Between now and then, please re-read the draft and send a message to the list is something is seriously wrong.


Barring any such shouting, we will request publication right after the meeting.


Thanks again,


Linda and Yoav

On 16 Jul 2019, at 15:42, Rafa Marin-Lopez < <>> wrote:


Dear all:

We submitted a new version of the I-D (v05) where we have applied several changes. In the following you have a summary of the main changes, which we will expand/explain during our presentation: 

- We have dealt with YANG doctors’ review (Martin's)

- We have dealt with Paul Wouters’ comments and Tero’s comments.


- We have added more specific text in the descriptions.

- Notifications have a simpler format now since most of the information that contained in the past is already handled by the Security Controller.

- State data has been reduced. For example, in IKE case, most of the information is related with IKE and not with the specific details about IPsec SAs that IKE handles (after all, IKE can abstract this information from the Security Controller).


- We have included text in the security section to discuss about the default IPsec policies that should be in the NSF when it starts before contacting with the SC such as the IPsec policies required to allow traffic between the SC and the NSF.


- We have added a subsection 5.3.4 about NSF discovery by the Security Controller.

- In order to specify the crypto-algorithms we have used a simple approach by including an integer and adding a text pointing the IANA in the reference clause. For example:

typedef encryption-algorithm-type {
           type uint32;
               "The encryption algorithm is specified with a 32-bit
               number extracted from IANA Registry. The acceptable
               values MUST follow the requirement levels for
               encryption algorithms for ESP and IKEv2.";
                "IANA Registry- Transform Type 1 - Encryption
                Algorithm Transform IDs. RFC 8221 - Cryptographic
                Algorithm Implementation Requirements and Usage
                Guidance for Encapsulating Security Payload (ESP)
                and Authentication Header (AH) and RFC 8247 -
                Algorithm Implementation Requirements and Usage
                Guidance for the Internet Key Exchange Protocol
                Version 2 (IKEv2).";


- We have included three additional Annexes with examples in about the usage of the YANG model.


- We have performed pyang --lint --lint-ensure-hyphenated-names and pyang -f yang --yang-line-length 69 in our model without warnings.


Best Regards.

Inicio del mensaje reenviado:


De:  <>

Asunto: [I2nsf] I-D Action: draft-ietf-i2nsf-sdn-ipsec-flow-protection-05.txt

Fecha: 7 de julio de 2019, 23:34:03 CEST

Para: < <>>

Cc:  <>

Responder a:  <>


A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Interface to Network Security Functions WG of the IETF.

       Title           : Software-Defined Networking (SDN)-based IPsec Flow Protection
       Authors         : Rafa Marin-Lopez
                         Gabriel Lopez-Millan
                         Fernando Pereniguez-Garcia
           Filename        : draft-ietf-i2nsf-sdn-ipsec-flow-protection-05.txt
           Pages           : 81
           Date            : 2019-07-07

  This document describes how providing IPsec-based flow protection by
  means of a Software-Defined Network (SDN) controller (aka.  Security
  Controller) and establishes the requirements to support this service.
  It considers two main well-known scenarios in IPsec: (i) gateway-to-
  gateway and (ii) host-to-host.  The SDN-based service described in
  this document allows the distribution and monitoring of IPsec
  information from a Security Controller to one or several flow-based
  Network Security Function (NSF).  The NSFs implement IPsec to protect
  data traffic between network resources.

  The document focuses on the NSF Facing Interface by providing models
  for configuration and state data required to allow the Security
  Controller to configure the IPsec databases (SPD, SAD, PAD) and IKEv2
  to establish Security Associations with a reduced intervention of the
  network administrator.

The IETF datatracker status page for this draft is:

There are also htmlized versions available at:

A diff from the previous version is available at:

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at  <>

Internet-Drafts are also available by anonymous FTP at:

I2nsf mailing list


Rafa Marin-Lopez, PhD
Dept. Information and Communications Engineering (DIIC)
Faculty of Computer Science-University of Murcia
30100 Murcia - Spain
Telf: +34868888501 Fax: +34868884151  <> e-mail:





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