Our AS400 does have multiple NIC's. Two ether and two token. The biggest
problem we could see on our sniffer was that traffic from a workstation
would come into the AS400 on one interface, say token2, and instead of going
out token2 back to the workstation originating the traffic, it would go out
an ether port, or the opposite token port? It didn't appear to have any
rhyme or reason where it passed traffic without the static routes. This was
sending traffic everywhere. Throughout all our token rings and ether
networks. All the retransmit traffic we seen on the sniffer seemed to be
from workstations to the AS400. I know very little about the IBM world so if
you could enlighten me as to why the IBM box seemed to get confused, I would
love to pass it on to it's sysadmins? BobS

-----Original Message-----
From: EA Louie 
Sent: Tuesday, May 01, 2001 11:52 AM
To: Sites, Bob; [EMAIL PROTECTED]
Subject: Re: Excessive Retransmissions UPDATE [7:2553]

thanks for sharing and updating us.   Just a few questions if you'd
indulge me, otherwise have a great day.
I'm kind of curious and very clueless since I don't know your network
architecture, but if you have a default gateway set on the AS/400 and IP
routing protocol running in your routers (even if it's static routes), then
unless you're running multiple NICs with multiple paths to the outside, why
would you need so many static routes in the AS/400 IP stack?  Why (for
example) would you not have all your IP routing handled the the router
level? I usually look at static routes on a host as a band-aid because I
didn't configure my network (read routers) properly - makes it hard for me
to point my finger at the clueless sysadmins for eliminting routes that they
really
shouldn't need if I have a properly configured infrastructure.
And at the broadcast storm level, do you know why your routers were not
picking those up and routing them for the host?  In other words, was ARP
working at the host and router level?

----- Original Message -----
From: "Sites, Bob" 
To: 
Sent: Monday, April 30, 2001 5:58 AM
Subject: Excessive Retransmissions UPDATE [7:2553]

Just wanted to update the list on this matter because I feel that it
could very easily happen to anyone of you and it was very difficult to
locate the problem. Got to blame this one on Big Blue hardware. Yes, the
AS400 was the cause of all our problems here, once again. Apparently several
days prior to this problem, the AS400 was upgraded and a rollover software
called Visions was added. This is similar in function to HSRP. A third party
software that allows rollover from one AS400 to another. Anyway, during the
setup for the rollover testing it was recommended that some static routes in
the AS400 be cleaned up and deleted. Way to go Visions! Our AS400 folks
didn't know any better and just deleted static routes down from about a
dozen to 4!!! Our
symptoms were major broadcast storms of retransmissions. Got to keep a
close eye on those big blue boys! Of course, as always, it was a "network"
problem and the network team solved it!!! Is it at all possible that IBM
could come up with a more worthless IP stack?

Bob Sites, CCNA
Winchester Medical Center

Do you have a TACAC's, Syslog server, & or SNMP database server.  Helps
you find the who, what, where, & when things started.  Sometimes you gotta
dig backwards when the obvious just won't present itself.  My guess is that
you have a link down, a flapping interface, or had bounce on a link that the
protocol wasn't configured to handle.
Please keep us posted with your success or failures
Phil

Perhaps someone could steer me on this problem that I've been fighting
for a day and half now. We are having a severe slowdown on our network and
when looking at the IP traffic from just about anywhere to anywhere, about
1/3 of the packets are being retransmitted? Sniffer error is "excessive
retransmissions."  Spent about 3 hours on the phone this morning with the
TAC and didn't really get anywhere. It appears that we are having a
broadcast storm of the retransmissions.  Any insight into what direction to
head would be greatly appreciated.  Would like to isolate the problem by
blades on the switches or routers, but being a hospital this is almost
impossible. We have 2 core 6509's with duplicate sups and msfc's.  Main
router is a 7200.

Bob Sites, CCNA
Winchester Medical Center



Bob Sites
System Engineer
Valley Health System, IS Dept.
[EMAIL PROTECTED]
540-536-4766


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