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Re: [SPAM] Re: ssh problem

Bertrand Yvain wrote:
> On Wed, Aug 26, 2009 at 05:57:38PM +0200, randall wrote:
>> not sure what i did to ***** this up, actually no idea what the MTU
>> actually does apart from what i read on google the last ten minutes.
> Did you check if it was set to 1500 beforehand?

yes, Tirla Adrian pointed this out to me.

host:~# ip link show
1: lo: <LOOPBACK,UP,10000> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen 100
    link/ether 00:07:e9:0f:74:61 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen 100
    link/ether 00:07:e9:0f:74:24 brd ff:ff:ff:ff:ff:ff
4: dummy0: <BROADCAST,NOARP,UP,10000> mtu 1500 qdisc noqueue
    link/ether a6:36:8d:f9:09:5b brd ff:ff:ff:ff:ff:ff
5: sit0: <NOARP> mtu 1480 qdisc noop
    link/sit brd

> The Maximum Transmission Unit defines the maximum size of the payload in
> every single frame sent on the interface.
> For ethernet, it's normalized to 1500 bytes.  Virtual no ethernet device
> does not support this value.  However, some devices silently discard
> larger frames.  On the other side, gigabit ethernet supports larger
> sizes and people tend to increase it around 9000.
> Things that affect the MTU are (mainly?) linked to encaspulation. Most
> commonly: ATM encap (like in DSL devices, or SONET/SDH links), 802.1q
> tagged vlan on a dumb switch...

think i have some serious reading to do before i can follow you on this
one ;)
i do have an internal "network" on that box with Vservers with a local
address, i did some rumbling in the configs there but is it correct that
you are saying it could be caused by my external ISP?

> You'll have to calculate, depending on the network setup, the largest
> MTU you can use.  

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