Re: Recommendation for SUA modifications
"Brian F. G. Bidulock" <[email protected]>
| Newsgroups | gmane.ietf.sigtran |
|---|---|
| Organization | http://www.openss7.org/ |
| Message-ID | <[email protected]> |
Haresign,
Signalling ASP congestion with SCON is a misuse of SCON.
Define some ASPTM messages to do the job. ASPTM messages are
only indexed off of Routing Context, do not contain any addresses,
and can use their own congestion level definition.
Leave SCON alone.
Here you go:
ASP Traffic Maintenance (ASPTM) Messages
0 Reserved
1 ASP Active (ACTIVE)
2 ASP Inactive (INACTIVE)
3 ASP Active Ack (ACTIVE ACK)
4 ASP Inactive Ack (INACTIVE ACK)
> 5 ASP Status (STATUS)
> 6 ASP Status Qry (STATUS QRY)
7 - 127 Reserved by the IETF
128 - 255 Reserved for IETF-Defined Message Class Extensions
>3.6.5. ASP Status (STATUS)
>
> The ASPST message is sent by an ASP to indicate to a remote SUA peer
> that it is experiencing congestion in processing signalling traffic
> for a particular Application Server.
>
> The format for the STATUS message is as follows:
>
> 0 1 2 3
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Tag = 0x0006 | Length |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> / Routing Context /
> \ \
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Tag = 0x0019 | Length |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> / ASP Congestion /
> \ \
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Tag = 0x0110 | Length |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> / Info String /
> \ \
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> Parameters
> Routing Context Optional
> ASP Congestion Mandatory
> Info String Optional
>
>3.6.4. ASP Status Qry (STATUS QRY)
>
> The STATUS QRY message is used to request an ASP-Status message
> from a remote SUA peer indicating the current congestion of the
> remote ASP.
>
> The format for the STATUS Qry message is as follows:
>
> 0 1 2 3
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Tag = 0x0006 | Length |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> / Routing Context /
> \ \
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Tag = 0x0004 | Length |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> / INFO String /
> \ \
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
>
> Parameters
> Routing Context Optional
> INFO String Optional
3.9. Common Parameters
These TLV parameters are common across the different adaptation
layers.
Parameter Name Parameter ID
============== ============
Reserved 0x0000
Not used in SUA 0x0001
Not used in SUA 0x0002
Not used in SUA 0x0003
Info String 0x0004
Not used in SUA 0x0005
Routing Context 0x0006
Diagnostic Info 0x0007
Not used in SUA 0x0008
Heartbeat Data 0x0009
Not Used in SUA 0x000A
Traffic Mode Type 0x000B
Error Code 0x000C
Status 0x000D
Not used in SUA 0x000E
Not used in SUA 0x000F
Not used in SUA 0x0010
ASP Identifier 0x0011
Affected Point Code 0x0012
Correlation ID 0x0013
Registration Result 0x0014
Deregistration Result 0x0015
Registration Status 0x0016
Deregistration Status 0x0017
Local Routing Key Identifier 0x0018
> ASP Congestion 0x0019
The ASP/IPSP state transition diagram is shown in Figure 1. The
possible states of an ASP/IPSP are:
ASP-DOWN: The remote SUA peer at the ASP/IPSP is unavailable and/or
the related SCTP association is down. Initially all ASPs/IPSPs will
be in this state. An ASP/IPSP in this state SHOULD NOT be sent any
SUA messages, with the exception of Heartbeat, ASP Down Ack and Error
messages.
ASP-INACTIVE: The remote SUA peer at the ASP/IPSP is available (and
the related SCTP association is up) but application traffic is
stopped. In this state the ASP/IPSP SHOULD NOT be sent any DATA or
SSNM messages for the AS for which the ASP/IPSP is inactive.
ASP-ACTIVE: The remote SUA peer at the ASP/IPSP is available and
application traffic is active (for a particular Routing Context or
set of Routing Contexts).
> ASP-CONGESTED: The remote SUA peer at the ASP/IPSP is available and
> application traffic is active (for a particular Routing Context or
> set of Routing Contexts), however, the ASP is experiencing congestion
> related to one or more Routing Contexts.
Figure 1: ASP/IPSP State Transition Diagram, per AS
| +--------------+ +---------------+
| | | ASPST | |
| +----------------------| ASP-ACTIVE |<------->| ASP-CONGESTED |
| | Other ASP/ +-------| | | |
| | IPSP in AS | +--------------+ +---------------+
| | Overrides | ^ | |
| | | | |<---------------------+
| | ASPAC/ | | ASPIA/
| |[ASPAC-Ack]| | [ASPIA-Ack]
| | | v
| | +--------------+
| | | |
| +------>| ASP-INACTIVE |
| | |
| +--------------+
| ^ |
ASPDN/ | | | ASPDN /
[ASPDN-Ack/]| ASPUP/ | | [ASPDN-Ack /]
SCTP CDI/ | [ASPUP-Ack] | | SCTP CDI/
SCTP RI | | | SCTP RI
| | v
| +--------------+
| | |
+--------------------->| ASP-DOWN |
| |
+--------------+
The possible states of an AS are:
AS-DOWN: The Application Server is unavailable. This state
implies that all related ASPs are in the ASP-DOWN state
for this AS. Initially the AS will be in this state.
An Application Server is in the AS-DOWN state before it
can be removed from a configuration.
AS-INACTIVE: The Application Server is available but no application
traffic is active (i.e., one or more related ASPs are in
the ASP-INACTIVE state, but none in the ASP-ACTIVE
state). The recovery timer T(r) is not running or has
expired.
AS-ACTIVE : The Application Server is available and application
traffic is active. This state implies that at least one
ASP is in the ASP-ACTIVE state.
> AS-CONGESTED: The Application Server is available and application
> traffic is active, however at least one ASP is in the
> ASP-CONGESTED state for the AS.
AS-PENDING: An active ASP has transitioned to ASP-INACTIVE or ASP-
DOWN and it was the last remaining active ASP in the AS.
A recovery timer T(r) SHOULD be started and all incoming
signalling messages SHOULD be queued by the SGP. If an
ASP becomes ASP-ACTIVE before T(r) expires, the AS is
moved to the AS-ACTIVE state and all the queued messages
will be sent to the ASP.
4.3.4.7 ASP Status Procedures
At any time that an ASP/IPSP is in the ASP-ACTIVE or ASP-CONGESTED states
for an AS, it can send an ASP Status message updating then congestion
level, or abatement of congestion, using the ASP Congestion parameter
contained in the message and pertaining to the included Routing
Context(s).
Upon receipt of an ASP Status message, an SG/IPSP MAY take actions with
regard to ASP congestion giving consideration for the congestion
and active statuses of the other ASPs/IPSPs in the AS. Actions could,
for example, include the redirection or redistribution of traffic within
a Load-Sharing AS.
4.3.4.8 ASP Status Qry Procedures
At any time that an ASP/IPSP is in the ASP-ACTIVE or ASP-CONGESTED states
for an AS, the peer SG/IPSP can send an ASP Status Qry message querying
the congestion state of the remote ASP/IPSP for the Application Servers
indicated by the Routing Context(s) contained in the query.
Upon receipt of an ASP Status Query message, if the ASP/IPSP is in the
ASP-ACTIVE or ASP-CONGESTED states for the indicated AS, the ASP/IPSP
MUST respond with an ASP Status message indicating the current congestion
status for the AS. Note that because only one ASP Congestion parameter
is contained in the ASP Status message, that multiple ASP Status messages
might be required in response to a single ASP Status Qry message.
...etc.
Fill in your own proprietary SG practices here.
--brian
Haresign Lincoln wrote: (Fri, 14 Oct 2005 09:18:59)
> Brian,
>
> You still have not addressed how to handle _ASP congestion_ in the two
> scenarios below. I have.
>
> At this point, I seem to have the agreement of several other members of
> the WG. You seem to be the only person opposed to making affected point
> code optional. I think Valerie's suggestion was a good one.
>
> I'm not sure this exchange is practical anymore since you and I have a
> basic disagreement over how to solve a problem. I've presented a
> solution. If you have another one, I'd be welcome to listen to it. But
> in lieu of another solution to the two problems outlined below, it is my
> opinion that this exchange is no longer serving a practical purpose. I
> look forward to feedback from other members of the WG and the SUA IG
> editors.
>
> Thanks for all your feedback.
>
--
Brian F. G. Bidulock
[email protected]
http://www.openss7.org/