[AusNOG] Telstra ADSL MTU

[Paul Wilkins]

If your CE and your SP both support RFC 4638, you should be able to manage
an MTU of 1500 and avoid all fragmentation by configuring:

pppoe-client ppp-max-payload 1500

As described in:

http://www.cisco.com/en/US/docs/ios/bbdsl/configuration/guide/bba_ppoe_client.pdf

Kind regards

Paul Wilkins

On 2 August 2016 at 21:42, Burt Mascareigne <Burt at stormnetwork.com.au>
wrote:

> Hi,
>
>
>
> We have client’s that have this constant problem.  I tweak the MTU to 1400
> sometimes… and then everyone works magically.  1492 causes havoc.  I once
> set It to 1500,  and it worked.. Don’t ask.. I took it to 1450 (I think)
> didn’t dare leave it on 1500 for ADSL.
>
>
>
> We’ve moved away from Cisco to SOPHOS, and there’s no mss-adjust.  We use
> a TD-8817 in bridge mode.  We have tried other bridge modems, no
> difference.
>
>
>
> What’s people recommendation for us non – cisco souls? Is it the bridge
> causing this?  Don’t see how, it’s dialler level.  Unless I’m being blond
> for something obvious.
>
>
>
>
>
> Regards,
>
>
>
>
>
>
> *Burt Mascareigne Mobile* 0414 450 962   *Office* (02) 9965 5422
> *Address* Level 19, 1 O’Connell Street, Sydney NSW 2000
> *Web* http://www.stormnetwork.com.au
>
>
>
> *From:* AusNOG [mailto:ausnog-bounces at lists.ausnog.net
> <ausnog-bounces at lists.ausnog.net>] *On Behalf Of *Shane Short
> *Sent:* Tuesday, 2 August 2016 8:03 PM
> *To:* Adam Baxter <adam1984 at gmail.com>
> *Cc:* AusNOG at lists.ausnog.net
> *Subject:* Re: [AusNOG] Telstra ADSL MTU
>
>
>
> 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> 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 *|* *E-mail*:
> nathan.brookfield at simtronic.com.au
>
>
> ------------------------------
>
> *From:* AusNOG <ausnog-bounces at lists.ausnog.net> on behalf of Adam Baxter
> <adam1984 at gmail.com>
> *Sent:* Tuesday, 2 August 2016 3:35 PM
> *To:* 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
>  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.
>
>
>
>
>
> _______________________________________________
>
> AusNOG mailing list
>
> AusNOG at lists.ausnog.net
>
> http://lists.ausnog.net/mailman/listinfo/ausnog
>
>
>
> _______________________________________________
> AusNOG mailing list
> AusNOG at lists.ausnog.net
> http://lists.ausnog.net/mailman/listinfo/ausnog
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ausnog.net/pipermail/ausnog/attachments/20160803/320f28ee/attachment.html>