[AusNOG] Telstra ADSL MTU

[Shane Short]

Is there a particular reason you're running 1452 on the dialer? Was it a 
troubleshooting step, or?

Adam Baxter wrote:
> Thank you!
>
> On 2 August 2016 at 15:39, Nathan Brookfield 
> <Nathan.Brookfield at simtronic.com.au 
> <mailto:Nathan.Brookfield at simtronic.com.au>> wrote:
>
>     Hi Adam,
>
>
>     As a rule your mss-adjust should be 40 bytes lower than your
>     actual MTU.  In theory you should have 1492 on the dialer and and
>     an mss-adjust of 1452 on the LAN interface.
>
>
>     If you're going to keep 1452 on the Dialer as the MTU you should
>     adjust the mss appropriately.  See if that helps at all.
>
>
>     Kindest Regards,
>
>     Nathan Brookfield (VK2NAB)
>
>     Chief Executive Officer
>
>     Simtronic Technologies Pty Ltd
>
>     *Local:* (02) 4749 4949 *|* *Fax:* (02) 4749 4950 *|*
>     *Direct:* (02) 4749 4951
>
>     *Web*: http://www.simtronic.com.au <http://www.simtronic.com.au/>
>     *|* *E-mail*: nathan.brookfield at simtronic.com.au
>     <mailto:nathan.brookfield at simtronic.com.au>
>
>     ------------------------------------------------------------------------
>     *From:* AusNOG <ausnog-bounces at lists.ausnog.net
>     <mailto:ausnog-bounces at lists.ausnog.net>> on behalf of Adam Baxter
>     <adam1984 at gmail.com <mailto:adam1984 at gmail.com>>
>     *Sent:* Tuesday, 2 August 2016 3:35 PM
>     *To:* AusNOG at lists.ausnog.net <mailto:AusNOG at lists.ausnog.net>
>     *Subject:* [AusNOG] Telstra ADSL MTU
>     Hi All,
>
>     I have had 2 Customers in the last few weeks that have had MTU
>     problems. This is my Dialer interface.
>
>     interface Dialer0
>      ip address negotiated
>      no ip redirects
>      no ip unreachables
>      no ip proxy-arp
>      ip mtu 1452
>      ip nat outside
>      ip virtual-reassembly
>      encapsulation ppp
>      load-interval 30
>      dialer pool 1
>      dialer-group 1
>      no cdp enable
>      ppp authentication chap callin
>      ppp chap hostname xxxx at direct.telstra.net
>     <mailto:xxxx at direct.telstra.net>
>      ppp chap password 7 xxxxx
>     end
>
>      I have never had any problems accessing websites until the last
>     few weeks. Does anyone know what might have changed at the Telstra
>     end? I had to set  "ip tcp adjust-mss 1452" on the Dialer
>     interface to make it work. Never had to in the past with a number
>     of other connections. Perhaps I should have all along?
>
>     Regards,
>
>     Adam.
>
>
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