[c-nsp] ip tcp adjust-mss

[Methsri Wickramarathna]

Thanks Blake & Tony,

Is this issue with My end core router , destination end device or
intermediate device ???

Is there any way I can find this ???



On Tue, Nov 5, 2013 at 7:22 AM, Blake Dunlap <ikiris at gmail.com> wrote:

> Yes. Don't do that.
>
>
> On Mon, Nov 4, 2013 at 6:59 PM, Methsri Wickramarathna <
> mmethw2003 at gmail.com> wrote:
>
>> Thanks Tony , John and Juergan...
>>
>> This has been issue for many sites mainly towards yahoo.com. Can any one
>> explain why this is happening for particular IPs in a subnet ???
>> We are using access list inbound & Outbound to prevent ICMPs cumming
>> inside
>> to our network, will it be creating this problem ????
>>
>>
>> On Tue, Nov 5, 2013 at 3:23 AM, <cnsp at marenda.net> wrote:
>>
>> > Hi, this looks like a CPE-device
>> > With static IP-adresses and routing.
>> >
>> > You may really want to set "ip tcp adjust-mss 1280"
>> > on _both_ your WAN and your (probably natted) LAN (L3) Interfaces.
>> > (_both_ sides, yes !)
>> >
>> > This will help you in most cases with
>> > MTU restrictions on
>> > - your link
>> > - home-"web"servers behind Broadband links
>> > etc.
>> >
>> > Yes, the value is not optimized but very computerish ( 2**10 + 2**8 ),
>> > but it is good for
>> > - pppoe (1500-8=1492)
>> > - l2tp forwarded dial-in sessions (l2tp overhead+pppoe leads to 1456)
>> > - even with an additional vlan tag ( so MTU will be 1452 found in most
>> > literature)
>> > - some other tunneled environments
>> >
>> > Iff you are an ISP,
>> > you will configure this _only_ on the virtual-template interfaces
>> > on your LNSes for broadband-termination .
>> >
>> > Keep it out of your core,
>> > You will not want to modify your valued customer's ip packets
>> > in your core network; here you want to use a MTU greater than 1500
>> > while on your BGP up/downstreams will stay at Ethernet-default 1500 .
>> >
>> > Sorry, very conservative, but will avoid may problems.
>> >
>> > Just my 0.01 $ on this
>> >
>> > Juergen.
>> >
>> > > -----Ursprüngliche Nachricht-----
>> > > Von: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] Im Auftrag
>> > > von Methsri Wickramarathna
>> > > Gesendet: lundi 4 novembre 2013 17:55
>> > > An: Pete Lumbis
>> > > Cc: cisco-nsp at puck.nether.net
>> > > Betreff: Re: [c-nsp] ip tcp adjust-mss
>> > >
>> > > Thanks Pete,
>> > >
>> > > If not a problem can any one look in to following mturoute taken ???
>> :)
>> > >
>> > > E:\>mturoute -t www.ubnt.com
>> > > mturoute to www.ubnt.com, 30 hops max, variable sized packets
>> > > * ICMP Fragmentation is not permitted. *
>> > > * Speed optimization is enabled. *
>> > > * Maximum payload is 10000 bytes. *
>> > >  1  +-  host: 116.12.78.1  max: 1500 bytes
>> > [...]
>> >
>> >
>>
>>
>> --
>> --
>> ________´$$$$`_____________________________,,,_
>> _______´$$$$$$$`_________________________´$$$`
>> ________`$$$$$$$`______,,________,,_______´$$$$´
>> _________`$$$$$$$`____´$$`_____´$$`____´$$$$$´
>> __________`$$$$$$$`_´$$$$$`_´$$$$$`__´$$$$$$$´
>> ___________`$$$$$$$_$$$$$$$_$$$$$$$_´$$$$$$$´_
>> ____________`$$$$$$_$$$$$$$_$$$$$$$`´$$$$$$´_
>> ___,,,,,,______`$$$$$$_$$$$$$$_$$$$$$$_$$$$$$´_
>> _´$$$$$`____`$$$$$$_$$$$$$$_$$$$$$$_$$$$$$´_
>> ´$$$$$$$$$`´$$$$$$$_$$$$$$$_$$$$$$$_$$$$$´_
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>> ______`$$$$$$$$$$$$$_$$$$$__$$_$$$$$$_$$´_
>> _______`$$$$$$$$$$$$,___,$$$$,_____,$$$$$´_
>> _________`$$$$$$$$$$$$$$$$$$$$$$$$$$$$$´_
>> __________`$$$$$$$$$$$$$$$$$$$$$$$$$$$´_
>> ____________`$$$$$$$$$$$$$$$$$$$$$$$$´_
>> _______________`$$$$$$$$$$$$$$$$$$$$´_
>>
>> ~~( ŊëŌ )~~
>> _______________________________________________
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>>
>
>


-- 
-- 
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´$$$$$$$$$`´$$$$$$$_$$$$$$$_$$$$$$$_$$$$$´_
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_______`$$$$$$$$$$$$,___,$$$$,_____,$$$$$´_
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~~( ŊëŌ )~~