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Re: [STDS-802-16] Issues for the usage of the Secondary managemen t connection



Dear Vladimir,

 

One of L3 control messages distributed over IP broadcast address is Agent Advertisement if Mobile IPv4 is used[RFC 3344]. If this message is missed then L3 will look for a new Agent. This means that the MSS will generate a packet to solicit a new Agent. Another example is Router Advertisement in IPv6 and mechanics are similar[RFC 3773]. Once a managed MSS decides to MIPv4 or IPv6 then, it should receive periodic broadcast management messages (actually multicast to specific MSSs which use MIPv4 or IPv6) from the network to manage connectivity.

 

Thanks,

Ronny

 


From: owner-stds-802-16@listserv.ieee.org [mailto:owner-stds-802-16@listserv.ieee.org]
Sent: Thursday, October 28, 2004 10:18 PM
To: STDS-802-16@listserv.ieee.org
Subject: Re: [STDS-802-16] Issues for the usage of the Secondary managemen t connection

 

Ronny,

 

You raised an interesting issue.

Can you please be more specific and provide exampe[s] of L3 control [management] information distributed over IP broadcast address.

Also what type of IP broadcast address must it be? [in specific IP domain?]

 

Thanks

 

Vladimir

 

-----Original Message-----
From: Ronny (Yong-Ho) Kim [mailto:ronnykim@LGE.COM]
Sent: Thursday, October 28, 2004 6:48 AM
To: STDS-802-16@listserv.ieee.org
Subject: Re: [STDS-802-16] Issues for the usage of the Secondary management connection

Dear All

 

We are discussing managing IP interfaces either for Data or for Management in mobile environment.

For IP interfaces, somehow Layer 3 signaling from the network should be transferred to the MSS in order to manage connection and we have discussed how it can be conveyed. We haven’t quite agreed which way is the best way.

Here, I would like to raise little different issue. If an MSS decides to use Mobile IP or IPv6 for Data or Management, not only unicast layer 3 control signal but also broadcast control signal from the network should be delivered to the MSS for IP interface management. However there is only unicast way to deliver this layer 3 broadcast signal through 802.16 air interface. If the layer 3 broadcast signal is transferred through default connection or secondary management connection, it will be a waste of resources. Someone might say it is not necessary for a BS to deliver layer 3 broadcast control signal to MSSs, however if the broadcast messages are not delivered, each and every MSSs, which are supposed to receive broadcast layer 3 control messages periodically, will generate unicast layer 3 signal, e.g, Agent Solicitation, or Router Solicitation through default or secondary management connection and unicast reply from the router or Agent to MSSs will be generated. This is even worse waste of bandwidth.

If we define a new management CID to deliver broadcast layer 3 management signal to the specific MSSs in a multicast way, then we can make IP interface management more efficiently. This management CID is only for certain MSSs that use MIP or IPv6.

 

I would like to hear your opinion on this.

 

Thanks,

Ronny

 

 


From: owner-stds-802-16@listserv.ieee.org [mailto:owner-stds-802-16@listserv.ieee.org]
Sent: Monday, October 18, 2004 5:52 PM
To: STDS-802-16@listserv.ieee.org
Subject: Re: [STDS-802-16] Issues for the usage of the Secondary management connection

 

Dear Chulsik, Ronny, All,

 

I would like to summarize the different options raised in this email thread with regards to Management Connection.

Please let me know your preferred option (of the below) so we can all know the baseline that each one of us starts from. Also let me know if I missed some options.

 

  1. MSS uses only one IP interface (both for data and management). Layer 3 and above protocols of this interface are used also for MSS manageability.

Implementation options:

1.1.  MSS chooses “un-managed” SS capability mode, open default data connection using static DSA (with much all classifier) to carry all default data traffic (including MIP/DHCP, TFTP, SNMP).

 

  1. MSS uses two IP interfaces, one for Data and one for Management. MSS has duplicated layer 3 services (for each interface).

Implementation options:

2.1  MSS chooses “managed” SS capability mode, use the secondary CID to carry DHCP,TFTP,SNMP of the management IP interface. Open a default data connection using static DSA (with much all classifier) to carry all default data traffic of the data IP interface (including MIP/DHCP, TFTP, SNMP).

2.2  MSS chooses “managed” SS capability mode, use the secondary CID to carry DHCP,TFTP,SNMP of the management IP interface and MIP/DHCP,TFTP,SNMP of the data IP interface. Open a default data connection using static DSA (with much all classifier) to carry all default data traffic of the data IP interface (excluding MIP/DHCP, TFTP, SNMP).

2.3  Same as 2.1 but with MIP capability on the Management connection IP IF.

2.4  Same as 2.2 but with MIP capability on the Management connection IP IF.

 

Currently the standard supports only option 1.1 and 2.1 above.

 

The disadvantages I see for 2.2. 2.3 and 2,4 above are as follows:

 

2.2 – If both IF shared the secondary CID, then how can the Network/BS conclude which of the IP allocation requests (MIP/DHCP) is for the data IF and which is for management IF. As for my understanding this was the aim of the Secondary CID connection.

 

2.3 – This solution can be applicable, however it requires the BS/Network to allocate two sets of colocated/home IP addresses and to maintain two mobile IP sessions in parallel, one for the Management connection and one for the Data one. IMO, it raises unnecessary complexity and usage of system expensive resources. In addition it can have high impact on the HO performance requiring to maintain two separate MIP HO procedures.

 

2.4 – Sheared disadvantages of 2.2 and 2.3.

 

Notes:

  1. “un-managed” mode explicitly define the lack of secondary CID.
  2. DSX transaction can create default CID between the BS and the MSS without a need for neither IP/Layer3 information nor connectivity.

 

BR,

- Yigal

 

Yigal Eliaspur

Intel Corp.

yigal.eliaspur@intel.com

 

 

-----Original Message-----
From: Ronny (Yong-Ho) Kim [mailto:ronnykim@lge.com]
Sent: Sunday, October 17, 2004 9:32 AM
To: Eliaspur, Yigal; STDS-802-16@listserv.ieee.org
Subject: RE: [STDS-802-16] Issues for the usage of the Secondary management connection

 

Dear Yigal and Chulsik,

 

Basically, I agree with Chulsik on the SMC issue.

I have comment and question on Yigals opinion, please refer to my comments inline.  

 

B.R,

 

Ronny

LG Electronics, Inc.


From: owner-stds-802-16@listserv.ieee.org [mailto:owner-stds-802-16@listserv.ieee.org]
Sent: Saturday, October 16, 2004 6:00 PM
To: STDS-802-16@listserv.ieee.org
Subject: Re: [STDS-802-16] Issues for the usage of the Secondary management connection

 

Hello Chulsik Yoon

Please find my comments inline...

Best regards

- Yigal

 

Yigal Eliaspur

Intel Corp.

yigal.eliaspur@intel.com

 

 

-----Original Message-----
From: csyoon@etri.re.kr [mailto:csyoon@etri.re.kr]
Sent: Friday, October 15, 2004 4:09 AM
To: Eliaspur, Yigal
Cc: STDS-802-16@listserv.ieee.org
Subject: Issues for the usage of the Secondary management connection

 

Hello Yigal,

 

I would like to discuss the usage of the Secondary Management Connection.

 

In the current draft standard, the usage of the secondary management connection is described like this (it is the result of the last meeting in Seoul, comment #580):

“Finally, the Secondary Management Connection is used by the BS and MSS to transfer delay tolerant, standards-based [Dynamic Host Configuration Protocol (DHCP), Trivial File Transfer Protocol (TFTP), SNMP, etc.] management messages.”

-- The text having the meaning that Mobile IP messages and router prefix advertisement are not transferred through the secondary management connection.

 

We have talked about the issues in the meeting, but we have found out some differences in our understanding, and the problems in the current specification.

 

You said:
The Secondary Management Connection can be used only for the management purposes, not for a user traffic transport, such as the SNMP messages for the SS. The IP address allocated by using the DHCP is used only for the management for the SS, not for the user traffic. The IP address for the user service can be allocated using the “default” Transport Connection. And the parameters for default Transport Connection is pre-assigned in each Base Station (BS).

 

But, these ideas have some problems:

1)       You mean that the protocol layer for the SS management (i.e., SNMP) is within the layer 2 (MAC) of the SS, and the path to that is on the Secondary Management Connection. And the user traffic (even in the case of DHCP or Mobile IP message for the IP address allocation for the user traffic) cannot use the secondary management connection.
In that case the protocol layers for the IP and above should be duplicated in the user plane and the management plane. But, the SNMP for the SS management and the Mobile IP for the IP connectivity management for user traffic can be discriminated in the IP layer by the “protocol” field. So, the two protocols can be well harmonized using the secondary management connection. And, it is not required to implement the duplicated protocol layers for the management plane and the user plane. The SNMP and the Mobile IP can be distinguished as a different application on the same IP layer. It is the better approach.

[E. Yigal] The current specification (16e/d) provides management mechanism that was mostly inherited from DOCSIS specification, and was design for fix SS (RG like) operation. This management framework requires 2 separate IP IF, one for Data traffic and one for Management traffic. The Management IP-IF is consider part of the 16 MAC and as a result the standard includes explicit reference to its layer 3 and above protocols (DHCP,IP,TFTP,SNMP). E.g : IP connectivity and  TFTP stage in the network entry, the definition of the Secondary Mgmt connection, etc.

An experiment to enhance the Mgmt IP-IF  to Mobile operation by replacing DHCP with MIP was a failure as for the amount of complexity it brought.

The aim of 16g is to define applicable and scale Mgmt solution for mobile operation, and this might be done using MAC layer Mgmt singling (not IP/SNMP based).

[Ronny] My question here is what kind of problem is caused if Secondary management connection is used for MIP? You mentioned replacing DHCP with MIP causes a lot of complexity but I disagree. Acquiring management IP address using MIP is very similar to DHCP if we consider MSS solicits Agent Discovery. If HO with MIP causes problem, DHCP causes same problem. However, as you know, MIP provides better IP management scheme than DHCP for mobiles.

Of course 16g can provide scalable Mgmt solution for mobile operation, but mobile management should be handled with IP address.  

Therefore, we can just have simple solution by using Secondary management connection for MIP and if there is any problem then we can fix it in either 16e or 16g.

 

2)      If we shall use the default transport connection for the IP connectivity management for the user traffic, then the DSA procedure should be proceeded before the allocation of the “default transport CID” for the user. But, generally DSA procedure requires the IP address for the transport connection, and even if it is not required, the “default transport connection” allocation is not possible. If we use the transport connection for the transfer of the Mobile IP and/or DHCP messages for the IP connectivity for the user traffic, then the IP address related parameters for the DSA procedure cannot be set. That means the parameters required should already be known to the SSs and the BSs. The default parameters should be used.
Because, the procedure is not described in anywhere in the specification, the BS cannot provide the allocated “default transport CID” to the user. In what management message? Using what parameter?

[E. Yigal] If the network/BS cannot allocate in advance (before operational stage) a co-located IP address based on the SS MAC address, the network/BS shell open a default data CID with a classifiers that is agnostic to a specific IP address (e.g. much all classifier). Once it has knowledge of the IP address and other higher level information (like ports) the system, based on needs, can triggered dynamic DSx with the appropriate information (note that more then one CPE IP address is possible in RG like environments).

[Ronny] I can not see the case when the network/BS can allocate a co-located IP address based on the SS MAC address. The function of default data CID looks pretty much like Secondary management connection to me. Why do we need to define a new default transport CID instead of SMC?

 

3)      If we should use the (default) Transport CID for IP connectivity management for the user traffic, then every terminal shall maintain the Basic CID, Primary Management CID, Secondary Management CID, and default Transport CID for signaling/control. That means SS should have minimum 4 CIDs , but the specification say that the minimum required CIDs each SS should have shall be not four but three. So, the usage of default Transport CID violates the specification.  

[E. Yigal] This is a network/operator decision if to provide the MSS data connectivity or not by allocating default data CID.

[Ronny] If default data CID is given to the MSS by a network/operator then it is required for MSS to manage this connection.

 

4)      If we use Transport CID instead of Secondary Management CID for the IP connectivity management for the user traffic, then the additional DSA-REQ/RSP procedures should be included in the network entry process. The DSA (connection establishment) procedure must be preceded for the transaction of the IP connectivity management procedures (DHCP or Mobile IP), because we should use the connection established before the transaction. But, if we use the Secondary management CID for that transaction, then the connection establishment procedure is not required. That means, the usage of the (default) Transport connection have more signaling overhead and causes more delay during the network entry process.

[E. Yigal] As I specified above the default data CID can be agnostic to the IP layer an above addressing, in addition static DSx operation is part of the network entry process.

5)      In the fixed environment, a subscriber station (SS) can be separated with equipment for the user traffic (such as multiple TEs) and the equipment for the air interface (such as MT), so that the Secondary management connection for the IP-based external management for the SS is feasible. But, generally in the mobile environment, the two equipment (TE and MT) should be integrated and used by only one user, so the separation of the path for the user traffic IP connectivity management  (default transport CID) and for the external management for the MSS (Secondary Management CID) is not a good approach.
Therefore, even in the case of the Secondary management connection is used for the external management for the MSS, the Secondary management connection should also be used as the transfer of the user traffic IP connectivity management and management (Mobile IP or DHCP).
-- We need to define the concept of MSS clearly. I think that the Mobile Router (One modem and multiple user equipment in mobile situation) concept is not appropriate for the current 16e specification.

[E. Yigal] As I specified above the Secondary Management connection is not applicable for Mobile operation.

6)      If we use the Secondary management connection only for the IP-based management of the SS externally, then the IP address for the SS management and the IP address for the user traffic (you mean, using the default transport connection) should be different. But, the IP address for the user traffic and the SS management can be shared, and has no problem. So, the separate IP address allocation procedure is duplicated and cause wasting up the IP address resources, especially in the case of MSS.

[E. Yigal] There are cons and pros for shearing or splitting IP based Management addressing with the data addressing. The standard does not prevent you to share the two addressing and to use the data only address. You can do that by choosing the “un-managed mode” capability – which means it’s out of the standard scope to deal with/define it.

 

7)      If we use the transport connection for the user traffic IP connectivity management, then the CID resources should be thrown away unnecessarily. If we can reuse the Secondary management connection, then we can save the CID resources.

8)      If we should proceed the handover process in the mobile environment over the subnets, then the transport connection for the user traffic IP connectivity management should be preceded before the transfer of the Mobile IP messages, that gives us a large unwanted delay for the handover process, and the system performance shall be greatly degraded.

[E. Yigal] Agree, see above – this is why we are looking for another solution for mobility (e.g. MAC mgmt based) in 16g

 

In summary, I would like to say my understanding and concept, and the specification should be reflected to support that:

1)       Secondary management connection can be used as a user traffic IP connectivity management (DHCP or Mobile IP).

2)      The IP address allocated by the DHCP procedure using the Secondary management connection, can be shared for the user traffic and the external management for the SS. So, there is no need to separate the path to the SS management and the user traffic by secondary management connection and the transport connection. 

3)      Mobile IP should be supported for the seamless HO across the subnets, and for the swift handover process, the Secondary management connection should also be used for the Mobile IP message transfer and the external management for the MSS for the managed MSS.

 

Best Regards,

 

Chulsik Yoon

 

Senior Engineer, ETRI



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