Maximum AP and AS message sizes

[Tim Alsop]

Eric,
 
I haven't been involved in any CableHome pilot deployments, but I understand that they exist. I think the best thing you can do is to test with a 4k limit and see if any problems occur. For PKINIT in this environment I would not expect the buffer size to be > 4k. I suspect you are planning to use Jungo or IPFonix KDC - have you asked the developers of these products for guidelines ?
 
Cheers, Tim.

  _____  

From: Naud, Eric [mailto:eric.naud at Terayon.com] 
Sent: 21 July 2003 18:16
To: 'Tim Alsop'; Naud, Eric; kerberos at mit.edu
Subject: RE: Maximum AP and AS message sizes


Hi Tim,
 
This is for Cablehome, it borrows much from the packetCable spec. What are the sizes you've seen for this context?
 
As for the UDP upper limit ;) I don't it would be wise to grab that much memory on this embedded device. 
 

Eric Naud

Software Development Engineer, Ottawa Design Center

Imedia Semiconductor

613.592.1052 x232

mailto:eric.naud at imedia.com <mailto:eric.naud at imedia.com> 



 ---------------------------------------------------------------------------------


-----Original Message-----
From: Tim Alsop [mailto:Tim.Alsop at CyberSafe.Ltd.UK]
Sent: July 21, 2003 11:47 AM
To: Tim Alsop; Naud, Eric; kerberos at mit.edu
Subject: RE: Maximum AP and AS message sizes


Eric,
 
I didn't mention before, but I understand the max size allowed for UDP communications is 65000 bytes, so this will be your upper limit.
 
Tim.

  _____  

From: Tim Alsop 
Sent: 21 July 2003 16:45
To: 'Naud, Eric'; Tim Alsop; kerberos at mit.edu
Subject: RE: Maximum AP and AS message sizes


Eric,
 
I have seen in excess of 4k, but in your particular requriements the buffer may not need to be anywhere near that large. If you can confirm the usage scenario (e.g. is this a PacketCable compliant MTA ?) I can give you a better feel for size limits involved.
 
Tim.

  _____  

From: Naud, Eric [mailto:eric.naud at Terayon.com] 
Sent: 21 July 2003 16:35
To: 'Tim Alsop'; Naud, Eric; kerberos at mit.edu
Subject: RE: Maximum AP and AS message sizes


Hi Tim,
 
Thanks for the quick response, but concerning the sizes are we talking 500 bytes, 1k, 2k? Statically allocating 4k on an embedded system is a little heavy so I'd like get a ballpark idea for the upper boudries on the reply messages. 
 
What are the largest numbers you've seen?
 

Eric Naud

Software Development Engineer, Ottawa Design Center

Imedia Semiconductor

613.592.1052 x232

mailto:eric.naud at imedia.com <mailto:eric.naud at imedia.com> 



 ---------------------------------------------------------------------------------


-----Original Message-----
From: Tim Alsop [mailto:Tim.Alsop at CyberSafe.Ltd.UK]
Sent: July 21, 2003 11:27 AM
To: Naud, Eric; kerberos at mit.edu
Subject: RE: Maximum AP and AS message sizes



Eric, 

You also need to consider : 

i) Whether IP addresses are stored in the tickets. In particular on a multi homed system the number of addresses can be quite large.

ii) Whether the KDC is a Microsoft KDC because PAC data will be stored in tickets. 

These, along with PKINIT requirements are the major contributors to large tickets, and hence large request/response packets to/from the KDC.

Cheers, Tim. 

-----Original Message----- 
From: Naud, Eric [mailto:eric.naud at Terayon.com <mailto:eric.naud at Terayon.com> ] 
Sent: 21 July 2003 16:23 
To: kerberos at mit.edu 
Subject: Maximum AP and AS message sizes 

Hi All, 

Can anyone tell me what the AP and AS message size maximums would be and what factor are to be considered? 

I'm using PKINIT so I know my AS request will be rather large due to the certificate. 

Thank! 

Eric Naud 
Software Development Engineer, Ottawa Design Center Imedia Semiconductor 
613.592.1052 x232 
mailto:eric.naud at imedia.com <mailto:eric.naud at imedia.com>  


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