From: amfahr@taligent.com (Jeff Amfahr)
Newsgroups: comp.protocols.appletalk
Subject: Re: AARP details clarification needed.
Date: 20 Aug 92 17:30:02 GMT
Followup-To: comp.protocols.appletalk
Organization: Taligent

In article <1992Aug20.132650.6380@abbott.com>, larry@abtlabs.uucp (Larry
Pajakowski) wrote:
> 
> 
> Help.
> 
> We have had a number of AARP storms and some of the network folks are
> attempting to understand what has been happening.  I'm posting this for
> them.  Your replys will be appreciated.
> 
> As usual if there is sufficient interest I'll mail or post a summary.
> 
> TNX
> 
> Larry Pajakowski
> Abbott Labs.
> larry@turing.abbott.com  (real e-mail address)
> 
> ______________________________________________________________________
> 
> 
> 
> We need definitive answers to the following list of questions.  Most 
> require exact parameter values, that should be publicly known, but which are 
> not in Apple's Phase 2 "Inside AppleTalk" book.  Some have definite values 
> that are dependent upon the implementation for a given protocol stack.  
> Where this is the case, please provide values and their associated protocol 
> stacks.  If known, please also provide any values suggested by Apple for 
> developers.  Apple has been unable to answer these questions--at least in
> the 8 days they've had to respond so far.  Where appropriate, I've included
> in parentheses (chapter-page) the page number reference in "Inside
> AppleTalk, 2nd Edition" where the topic occurs. 
> 
> 
> 1. What is the typical size of an Address Mapping Table, or how many 
> entries can the AMT hold before old entries are purged to make room for new 
> ones?  [book just says there is a "cache" of mappings]  (2-7)
> 
This varies from implemtation to implematation.
> 2. How many AARP Probe packets must be broadcast by the protocol stack 
> attempting to verify that its tentative protocol address is not in use by
> any other node on the data link?  [the book just says "a number" of probe
> pkts] (2-7) 
> 

Inside AppleTalk states that for EtherTalk and TokenTalk there are 10
packets  sent out 1/5 second apart

> 3. From book: "If [an AARP] Response packet is not received "within a
> specified time interval," then AARP retransmits the Request packet. 
> The question is, WHAT is the value of the time-out interval mentioned 
> above?  How long must AARP wait before retransmitting the Request 
> packet?  (2-8)
> 
> And how MANY retries are attempted?  [book says just "a specified maximum 
> number of times]  (2-8)
> 
> 4. What is the timeout value that is allowed to expire before an AMT entry 
> is aged?  (2-10)
> 
> 5. Does a Macintosh end-node send the equivalent of a DECnet end-node's 
> HELLO packet to refresh its router's AMT?
> 
If by end-node you mean a non-router, then the answer is no. A router is
suppose to send out RTMP packets periodiacly.

> 6. Does a Macintosh end-node maintain an AMT?  If so, what is its size, or 
> how many entries can it hold?
An end-node definitly mainatins an AMT. Its size is dependent on the link
implemantation (i.e., Apple does not supple AARP for you since it is link
dependent.

Hope this info helps

Jeff Amfahr
Taligent

These opinions are mine. But they can be yours for a price.