Subject: questions to netatalk
From: Guenter Roeck (roeck@conware.de)
Date: Fri Nov 27 1992 - 06:05:43 EST
Hello,
I am an implementer of AppleTalk router software at Conware GmbH. After
examination of the Michigan implementation netatalk 1.2.1 and comparison with
the AppleTalk definitions in 'Inside AppleTalk' edited by Sidhu, Andrews and
Oppenheimer, I noticed a lot of differences. In some cases it's not obvious to
me why these changes were made and even if they are correct. It would be helpful
to me, if you sent back some comments to the following list of differences:
NBP:
1. In NBP e.g. register packets are sent to the AppleTalk internet
address 0000.00 .I assume that these packets are handled by DDP as
local packets and no packets are sent out to any data link. Is this
assumption correct ?
RTMP:
2. Bad entries are not deleted from the routing table at a RT-check.
3. Bad entries and entries with a distance >= 15 are included in RTMP
data packets. Bad entries are sent with the distance given in the
routing table.
4. A routing table entry does not have a port number associated with it.
5. Only better routes are accepted from any neighboured routers.
AppleTalk Phase I (the book) also accepts routes with equal
distances.
6. No worse route is accepted, if the routing table entry's gateway is
equal to the source address in the RTMP packet (and the ports are
equal).
7. Split horizon is applied (split horizon is not defined in Phase I).
8. Each router must read the source of a RTMP data or a RTMP response
packet if the receiving port isn't already configured with a nonzero
network number. This is not being done in netatalk. Thus, how is the
port being configured if it's not a seed router ?
9. Only a timer of 30 seconds is used for both the validity and the send
timer. Accordingly to the specification of Phase I the following
timer values must be used:
validity timer 20 seconds
send timer 10 seconds
Point 2. could cause a large routing table, and together with point 3.
will result in large RTMP data packets. Also the exhaustive search
through the RT is more expensive in computing time.
Furthermore, counting to infinity can occur in case of split horizon.
Therefore the distance of entries should be checked before updating
routing entries or no routing information may be sent about routes with
a distance greater than 14. Otherwise counting to infinity wouldn't
break.
ZIP:
10. ZIP Takedown and ZIP Bringup are not handled.
11. The ZIP Query-Retransmission timer is set to 30 seconds (Phase I
defines 10 seconds).
Thanks in advance
Konrad Juelg
--------------------------------------------------------------------------
Konrad Juelg - Conware GmbH Phone: (0049) 721-9495-0
Internet: juelg@conware.de Fax: (0049) 721-9495-146
--------------------------------------------------------------------------
This archive was generated by hypermail 2b28 : Sat Dec 18 1999 - 16:09:05 EST