Re: Very Strange Problem

From: Marko Milivojevic <markom_at_ipexpert.com>
Date: Fri, 2 Jul 2010 02:28:36 -0700

You need to apply MSS adjustment on LAN interface, not the dialer.

--
Marko Milivojevic - CCIE #18427
Senior Technical Instructor - IPexpert
Mailto: markom_at_ipexpert.com
Telephone: +1.810.326.1444
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:: Sent from my phone. Apologies for errors and brevity. ::
On 1 Jul 2010, at 21:35, Sidney Spencer <ccie22926_at_gmail.com> wrote:
> I tried changing the MTU as well as the MSS on the dialer interface an still
> have the same problem.. Any other thoughts?? There are about 30 machines
> that this is affecting if changing the MTU on the workstation is the fix, I
> would like to see if there is anything else before hand..   Thanks all..
> 
> On Thu, Jul 1, 2010 at 10:14 PM, Tyson Scott <tscott_at_ipexpert.com> wrote:
> 
>> Your dialer MTU should be no higher than 1492.  Right now it is at the
>> default of 1500.
>> 
>> Try changing the MTU on the host itself to 1300 or something.  I changed my
>> MTU on my laptop to 1350 to solve problems when windowing was being ignored
>> by servers.
>> 
>> To do it on a windows machine follow these instructions
>> 
>> http://smallvoid.com/article/vista-tcpip-mtu.html
>> 
>> See if that solves the problem
>> 
>> Regards,
>> 
>> Tyson Scott - CCIE #13513 R&S, Security, and SP
>> Managing Partner / Sr. Instructor - IPexpert, Inc.
>> Mailto: tscott_at_ipexpert.com
>> 
>> 
>> -----Original Message-----
>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
>> Sidney Spencer
>> Sent: Thursday, July 01, 2010 11:02 PM
>> To: Cisco certification
>> Subject: Very Strange Problem
>> 
>> Hello all,
>> 
>> 
>> I have run into an issue that I am having the hardest time trying to
>> figure
>> out what it is.  Here is what is happening:
>> 
>> I have a 2801 Router with and ASDL wic installed in it.  There is currently
>> 3 site to site VPN's configured, and basic routing, and PAT. What is
>> happening is every time a user behind this router tries to access the
>> internet (going to a site www.yahoo.com or facebook etc) it basically sits
>> there and just continues to load and take forever but never comes up, if I
>> go to www.google.com that has no images to load it comes up really quick
>> with no issue.  Here is a kicker, if I try to load a web page on internal
>> site on the other side of the tunnel everything comes up as normal with no
>> problems, the issue is only when I try to access external websites from
>> that
>> location.  I am able to ping and telnet to port 80 with no problems.  I
>> thought it was a fragmentation issue, so I changed MTU and MSS as low as
>> 1200 and the problem still persists.  Has anyone else seen this issue?  I
>> found the issue on the internet but have not seen where anyone has come up
>> with a fix for it, so I thought I would see if anyone here may have seen
>> this issue and resolved?
>> 
>> The configuration is pretty basic (snippits)
>> 
>> F0/0 - Shutdown
>> !
>> interface FastEthernet0/1
>> description $ES_LAN$
>> ip address 192.168.90.1 255.255.255.0
>> ip nat inside
>> ip virtual-reassembly
>> duplex auto
>> speed auto
>> 
>> interface ATM0/3/0
>> no ip address
>> no ip mroute-cache
>> no atm ilmi-keepalive
>> dsl operating-mode auto
>> hold-queue 224 in
>> !
>> interface ATM0/3/0.1 point-to-point
>> pvc 8/32
>> encapsulation aal5snap
>> pppoe-client dial-pool-number 1
>> !
>> !
>> interface Dialer1
>> ip address negotiated
>> ip nat outside
>> ip virtual-reassembly
>> encapsulation ppp
>> dialer pool 1
>> dialer-group 1
>> no cdp enable
>> ppp authentication chap pap callin
>> ppp chap hostname xxxxxxxxx
>> ppp chap password 0 xxxxxxxx
>> ppp pap sent-username xxxxxxxxxx password 0 xxxxxxxxx
>> 
>> ip route 0.0.0.0 0.0.0.0 Dialer1
>> 
>> ip nat inside source route-map internet_nat interface Dialer1 overload
>> 
>> 
>> ADSL is used because that is the only option in the location in which this
>> router is located. Any ideas on where I should be looking is much
>> appreciated, the next step for me is to probably open a TAC case but wanted
>> to get others thoughts first..
>> 
>> 
>> Sid
>> 
>> 
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>> 
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> 
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Received on Fri Jul 02 2010 - 02:28:36 ART

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