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author | brian <brian@FreeBSD.org> | 2001-06-18 14:59:36 +0000 |
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committer | brian <brian@FreeBSD.org> | 2001-06-18 14:59:36 +0000 |
commit | 14263ff751db1d878bad974a406737533ea6b70c (patch) | |
tree | 5bb2d9ee08d5ff16a973109f6f61899430eeb81e /usr.sbin/ppp/ppp.8 | |
parent | fd0a00a7295105bd1c94ad22b13d090c15c702a4 (diff) | |
download | FreeBSD-src-14263ff751db1d878bad974a406737533ea6b70c.zip FreeBSD-src-14263ff751db1d878bad974a406737533ea6b70c.tar.gz |
Handle hardware-imposed MTU/MRU limitations. PPPoE will no longer
allow MRU/MTU negotiations to exceed 1492.
Add an optional ``max'' specifier to ``set m[rt]u'', ie.
set mtu max 1480
Bump the ppp version number.
Sponsored by: Monzoon Networks AG and FreeBSD Services Limited
Diffstat (limited to 'usr.sbin/ppp/ppp.8')
-rw-r--r-- | usr.sbin/ppp/ppp.8 | 46 |
1 files changed, 37 insertions, 9 deletions
diff --git a/usr.sbin/ppp/ppp.8 b/usr.sbin/ppp/ppp.8 index acfd8fc..42743be 100644 --- a/usr.sbin/ppp/ppp.8 +++ b/usr.sbin/ppp/ppp.8 @@ -4917,32 +4917,60 @@ Setting this option enables Multi-link PPP negotiations, also known as Multi-link Protocol or MP. There is no default MRRU (Maximum Reconstructed Receive Unit) value. If no argument is given, multi-link mode is disabled. -.It set mru Op Ar value +.It set mru Oo max Ns Oo imum Oc Oc Op Ar value The default MRU (Maximum Receive Unit) is 1500. If it is increased, the other side *may* increase its MTU. -There is no point in decreasing the MRU to below the default as the +In theory there is no point in decreasing the MRU to below the default as the .Em PPP -protocol *must* be able to accept packets of at least 1500 octets. +protocol says implementations *must* be able to accept packets of at +least 1500 octets. +.Pp +If the +.Dq maximum +keyword is used, +.Nm +will refuse to negotiate a higher value. +The maximum MRU can be set to 2048 at most. +Setting a maximum of less than 1500 violates the +.Em PPP +rfc, but may sometimes be necessary. +For example, +.Em PPPoE +imposes a maximum of 1492 due to hardware limitations. +.Pp If no argument is given, 1500 is assumed. -.It set mtu Op Ar value +A value must be given when +.Dq maximum +is specified. +.It set mtu Oo max Ns Oo imum Oc Oc Op Ar value The default MTU is 1500. At negotiation time, .Nm -will accept whatever MRU or MRRU that the peer wants (assuming it's -not less than 296 bytes). +will accept whatever MRU the peer requests (assuming it's +not less than 296 bytes or greater than the assigned maximum). If the MTU is set, .Nm -will not accept MRU/MRRU values less than +will not accept MRU values less than .Ar value . -When negotiations are complete, the MTU is assigned to the interface, even -if the peer requested a higher value MRU/MRRU. +When negotiations are complete, the MTU is used when writing to the +interface, even if the peer requested a higher value MRU. This can be useful for limiting your packet size (giving better bandwidth sharing at the expense of more header data). .Pp +If the +.Dq maximum +keyword is used, +.Nm +will refuse to negotiate a higher value. +The maximum MTU can be set to 2048 at most. +.Pp If no .Ar value is given, 1500, or whatever the peer asks for is used. +A value must be given when +.Dq maximum +is specified. .It set nbns Op Ar x.x.x.x Op Ar y.y.y.y This option allows the setting of the Microsoft NetBIOS name server values to be returned at the peers request. |