Re: Automatically setiting mtu
Hi David Thanks for reply - and explanations. > You can set the MTU on an interface from /etc/network/interfaces: > > iface eth0 inet static > address 10.20.30.53 > netmask 255.255.255.240 > broadcast 10.20.30.63 > gateway 10.20.30.49 > mtu 1460 This would be ideal except, my interfaces section here is set to dhcp, not static - I have tried to see if I can get away with using it with dhcp, but alas the man page is correct. > > > After a bit of googling the only way, out of many, that seems to work on > > this box is to delete the default route and use the route command to > > reinstate it with the mss parameter. > > You could probably do that too; is this a particularly complicated > router machine? Nah - this box doesn't route at all, but its default route is set to BOXNAME, which acts as a dhcp server, and gateway to the internet. At the moment I manually: route delete default route add default gw BOXNAME mss 1454 but I often work in the box from off site and don't want to have to do this. > > > I've experimented with the option interface-mtu parameter in > > dhclient.conf > > In my experience that option is completely ignored; it *might* work if > the DHCP server is configured to send it and the client is configured > to receive it, but there's no guarantees. Phew - not just my imagination > > > Anyone ever had to play with this to get through the cursed ms > > internet sharing reigiem? > > (!) My (uninformed) impression is that that was just a NAT, which > shouldn't require resetting your MTU. You might run Debian on your > gateway machine instead; it's much more configurable, and much easier > to find out what exactly is going on. 'apt-get install ipmasq' should > get you going for straightforward things. > > What exactly *is* your configuration here? This is a network of 5 home pc's all running XP Prof. and one debian box. The internet gateway is one of the XP boxes doing the 'network sharing thing' i.e. NAT. The built in 'firewall' in XP port forwards so that ssh, incoming ftp, postgres and others are all forwarded to the debian box. When we first set up the XP network with the ADSL connection on the gateway, there was all sorts of problems with the NAT machines (all XP and win98 at the time) using the internet - a bit of googling revealed we had to set the MTU to 1454 (a windows registry setting). The debian machine is a relative new arrival and has always had problems reaching the net through BOXNAME. We figured that perhaps we had to do the samething for debian as we did for xp, a bit of googling and here we are now, using route to add the mtu value with the mss parameter, but wanting something more elegant and automatic. I've also installed iproute as Jan suggested in previous post, but haven't had a chance to play, and not sure that it can improve things any more that they are. Thhanks for your reply and taking the time to read this Glenn -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: Automatically setiting mtu
glenn <[EMAIL PROTECTED]> writes: > Firstly just because I used the tla MTU doesn't mean I undertand it, "Maximum transmission unit", it's the largest packet size that can be sent out over some particular interface. For Ethernet the standard MTU is 1500 bytes; you can apparently get better interactive performance over very slow connections (modem) by setting a lower MTU, and some odd types of network connections may also require a lower MTU (e.g., IP-over-IP tunnels consume 40 bytes of the packet, so the MTU on a tunnelled connection is generally 1460 bytes). In theory IP can deal just fine with fragmenting packets larger than a given connection's MTU, but in practice some broken sites (slashdot.org is a good one) set flags that cause fragmented packets to be dropped. > I look after a box where I need to set it, and would like it done > automatically. You can set the MTU on an interface from /etc/network/interfaces: iface eth0 inet static address 10.20.30.53 netmask 255.255.255.240 broadcast 10.20.30.63 gateway 10.20.30.49 mtu 1460 > After a bit of googling the only way, out of many, that seems to work on > this box is to delete the default route and use the route command to > reinstate it with the mss parameter. You could probably do that too; is this a particularly complicated router machine? > I've experimented with the option interface-mtu parameter in > dhclient.conf In my experience that option is completely ignored; it *might* work if the DHCP server is configured to send it and the client is configured to receive it, but there's no guarantees. > Anyone ever had to play with this to get through the cursed ms > internet sharing reigiem? (!) My (uninformed) impression is that that was just a NAT, which shouldn't require resetting your MTU. You might run Debian on your gateway machine instead; it's much more configurable, and much easier to find out what exactly is going on. 'apt-get install ipmasq' should get you going for straightforward things. What exactly *is* your configuration here? -- David Maze [EMAIL PROTECTED] http://people.debian.org/~dmaze/ "Theoretical politics is interesting. Politicking should be illegal." -- Abra Mitchell -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: Automatically setiting mtu
On Tue, Jan 20, 2004 at 01:56:51AM +1100, glenn wrote: > Firstly just because I used the tla MTU doesn't mean I undertand it, but > I look after a box where I need to set it, and would like it done > automatically. The way to set a MTU is (assuming you have the iproute package installed): # ip l s eth0 mtu 6969 where `6969' is the desired new MTU, in octets. You can set this in /etc/network/interfaces as a pre-up command, at least. HTH. Jan. -- Jan Minar "Please don't CC me, I'm subscribed." x 9 pgp0.pgp Description: PGP signature
Automatically setiting mtu
Hi Firstly just because I used the tla MTU doesn't mean I undertand it, but I look after a box where I need to set it, and would like it done automatically. After a bit of googling the only way, out of many, that seems to work on this box is to delete the default route and use the route command to reinstate it with the mss parameter. Is there a way can have route automatically take up a specific value for its mss parameter??? I've experimented with the option interface-mtu parameter in dhclient.conf (as this machine is assigned an ip address) as well as the mtu option in the interfaces file for eth0 (even though its only for static option) Anyone ever had to play with this to get through the cursed ms internet sharing reigiem? tia glenn -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
