Re: I think this is outrageous, but am i wrong?

[Matt Moeller <moellermatthew () yahoo com>]

I believe the original statement was that HDX will prevent equipment buffer overrun and subsequent discards.  I stick 
by that.




________________________________
From: Ryan Zuidema <ryan.zuidema () knchlaw com>
To: Community support list for Wireshark <wireshark-users () wireshark org>
Sent: Wed, February 17, 2010 5:44:46 PM
Subject: Re: [Wireshark-users] I think this is outrageous, but am i wrong?

 
I do not agree that half duplex will prevent T-1 overrun. Half
duplex can only introduce additional delay/loss over the link. With the collisions
associated with half duplex you will have a lot more garbage going across your
T-1 (retransmits etc…). Also you’ll have delays as the computers
back off during the retransmission process. Half duplex has no positive
effect in your situation, and could be contributing to the issues your
having.
 
I strongly recommend switching it over to Full duplex.
It’s probably a negotiation issue. During your next outage window force
it to Full duplex and test it out.
 
That said, you probably have other issues in play here; it is
quite easy to overuse a T-1. 
 
-Ryan
 
From:wireshark-users-bounces () wireshark org
[mailto:wireshark-users-bounces () wireshark org] On Behalf Of jack craig
Sent: Wednesday, February 17, 2010 2:37 PM
To: wireshark-users () wireshark org
Subject: Re: [Wireshark-users] I think this is outrageous, but am i
wrong?
 
its a cisco pix 506, not new,
but capable of full/half duplex.

one response i got was that the half duplex would keep the t1 from being
overrun as much.
you dont agree? 

personally, i find it hard to imagine a case where half duplex is better than
full,
but i have learned other new information today.

Thx very much for your response, jackc....

On 02/17/2010 12:42 PM, Ryan Zuidema wrote: 
The bottleneck to the cloud is your T-1. No firewall being set
to 10Mbs/100Mbs/1Gbps will make any difference there. In your situation 10Mbps
is more than enough. I wouldn’t be shocked to see 10Mbps dealing with WAN
type equipment, precisely because it’s more than enough to fill the
average pipe.  *10Mb = Not outrageous at all*
 
Half duplex could be an issue with high packet rates. This is
possible even at low bandwidth utilization. If you’re running VoIP,
terminal emulation or any other type of high packet rate streaming you could
see a lot of collisions. Half-duplex is more unusual and something I would
change. *HDx = Not outrageous, but worth fixing/changing*
 
Is the firewall capable of full duplex? Perhaps it just failed
to properly auto-negotiate? What type of firewall is it (make/model)?
 
-Ryan
 
From:wireshark-users-bounces () wireshark org [mailto:wireshark-users-bounces () wireshark org] On Behalf Of jack craig
Sent: Wednesday, February 17, 2010 10:22 AM
To: Community support list for Wireshark
Subject: [Wireshark-users] I think this is outrageous, but am i wrong?
 
Hi
Wireshark Folks,

The below query is not Wireshark specific, just a basic networking topic.
Pls hit delete if you dont care to read more.

I pose this query to this forum just because the collection of talent here
should vindicate or refute my own sanity.

pls consider this network topology? 

a site has a T1 to the cloud. following that T1 into the domain, we first
encounter the T1 router,
then on to a firewall, and arriving finally at a 10/100 Mbps switch where its
distributed to internal users.

our access to the cloud has been degraded so we look for reasons why?

we find that the firewall is configured on both input/output sides to be 10
Mbps, half duplex.

AFAIK, upgrading the firewall interfaces to 100 Mpbs/FDx would increase the
throughput by 10 times (ideally) 
and enable bidirectional traffic (as opposed to limiting to a single direction at
once).

am i missing something obvious here? is there any reason a 10 Mbps/HDx link is
better than 100Mbps/FDx ??

tia, jackc...


-- 
Jack Craig
Software Engineer
831.461.7100 x120
www.extraview.com 
  
  
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-- 
Jack Craig
Software Engineer
831.461.7100 x120
www.extraview.com 


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