-Erik
-----Original Message-----
From: Erik P. Power [mailto:erik@sitespecific.net]
Sent: Monday, February 22, 1999 12:39 PM
To: rfe@livingston.com
Subject: FW: Hung Multilink interfaces on PM3 [SUP1999021700000076]
This is a request for a feature enhancement in ComOS for the PM3 line of
access servers. We've run into difficulty with out PM3 keeping connections
to ISDN-connected ports open if the remote ISDN device manually disconnects
from the B channels. This is on a PM3 running ComOS 3.8.2, SNMP and OSPF
enabled, with CT1s connected to lines 0 and 1. The CT1s are configured as
follows: ESF framing, B8ZS encoding, FXS loop start signaling.
This problem has been observed using both an Ascend Pipeline 50 and an
Netgear RT328. The routers were configured for DOSBS and NAT. The details of
the problem are as follows:
If the B channels are manually disconnected via a command interface with
either of the ISDN routers we tested, the routers fail to send an
LCP_TERMINATE_REQUEST to our PM3. Instead, they simply negotiate the
disconnect with the telco's ISDN switch. The symptoms of the problem then
become apparent--the PM3 never received a request for disconnect, so it
assumes the connection is still open. The ports that were in use for the
connection remain in use until the session times out after 20 minutes (our
idle-timeout setting).
While I agree that the core of the problem lies with the ISDN routers'
operating system code, I believe that the PM3 could be improved so that it
is not adversely affected by other vendors' shortcomings. The simplest
solution, from my point of view, would be to implement a feature addition to
ComOS. The new feature would send keepalive packets to idle ISDN connections
every set interval of seconds (10, for example) to make sure the connection
is really still there. After failing to receive responses to a set number
(say, 3) of successive keepalive packets, the PM3 would drop the connection.
If this is a planned addition to future ComOS versions, please let me know,
I would feel much better about leaving my PM3 unattended knowing that a
feature like this is present and active. Thanks.
______________________________________________________
Erik P. Power Site Specific, Inc.
erik@sitespecific.net 1402 3rd Ave. Suite 324
Voice: (206) 652-0677 Seattle, WA 98101
Fax: (206) 652-0676 http://www.sitespecific.net
______________________________________________________
>
>-----Original Message-----
>From: support@livingston.com [mailto:support@livingston.com]
>Sent: Friday, February 19, 1999 5:46 PM
>To: erik@sitespecific.net
>Cc: dharvey@livingston.com
>Subject: Re: Hung Multilink interfaces on PM3 [SUP1999021700000076]
>
>
>We actually found the cause of the problem. It seems that both the Ascend
>Pipeline 50 and the Netgear RT328 don't bother to send an
>LCP_TERMINATE_REQUEST if you manually hang up the B channels. So, the
>physical link dies, but the PM3 still thinks it's open and refuses to clear
>the interfaces. The solution is to never manually hang up the B channels,
>however I'm discouraged that the PM3 doesn't use some sort of keepalive to
>make sure a connection is still valid. I think the majority of the blame
>should be assigned to the ISDN routers, who aren't acting in a civil manner
>when disconnecting B channels manually, however I would like to see a
>keepalive feature added to ComOS so that the poor performance of remote
>routers doesn't foul up our NAS. Perhaps this is a feature that will be
>included in ComOS 3.9? I've seen at least one other person (in my recent
>memory) ask for such a feature on the portmaster-users list, and I'm sure
>everyone would appreciate functionality like this. Thanks!
-
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