Is there any way to change the default MTU in Linux dynamically? (OK, I know that there *is*, I just can't work out how).
Specifically, is the change system wide, or could I change it on a per interface basis? I guess I could use ifconfig for eth0, but I am unsure as to where it is set for ppp0. e.g. ppp0 (MTU=<1000) and eth0 (MTU=1000)
Is there any kind of mtu learning daemon for interfaces? (i.e. MTU actually being worked out by testing fragmentation of packets on the network)
Ricardo, being inquisitive ;) _______________________________________________ "There are several codes, and I know several of them." -Mr. Precise. http://www.rscampos.net Check my online diary out: http://www.rscampos.net/blog.html
On Wed, 3 Apr 2002, Ricardo Campos wrote:
Is there any way to change the default MTU in Linux dynamically? (OK, I know that there *is*, I just can't work out how).
Specifically, is the change system wide, or could I change it on a per interface basis? I guess I could use ifconfig for eth0, but I am unsure as to where it is set for ppp0. e.g. ppp0 (MTU=<1000) and eth0 (MTU=1000)
well to do it for ppp0 you would use ifconfig ppp0 mtu 100, you would never want to change the mtu for all of your interfaces on a system wide level, as you would most likely end up breaking something.
Is there any kind of mtu learning daemon for interfaces? (i.e. MTU actually being worked out by testing fragmentation of packets on the network)
Erm don't know, although you most likely would always want to leave the MTU at default, if you need to change it then you are most likely having other problems with your network interface, you would look for (I think) framing errors in the output of ifconfig although it may be one of the other error metrics.
Adam
on Wed, Apr 03, 2002 at 10:43:50PM +0000, Ricardo Campos wrote:
Is there any way to change the default MTU in Linux dynamically? (OK, I know that there *is*, I just can't work out how).
iproute2 allows you to set the mtu and the tcp advertised mss on a per route basis. Something like:
ip route change blah mtu 1234 advmss 1194
Is there any kind of mtu learning daemon for interfaces? (i.e. MTU actually being worked out by testing fragmentation of packets on the network)
I've not seen it implemented as a daemon, generally it's implemented in the kernel as Path MTU discovery. This described by RFC 1191. But there are unfortunately many networks that don't play nice with this.
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Adam Bower -
Ricardo Campos -
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