* [LARTC] 2 default gw in redhat 6.2
2001-02-01 19:49 [LARTC] 2 default gw in redhat 6.2 fabian1 fabian1
@ 2001-02-01 21:06 ` bert
2001-02-01 21:18 ` Arthur
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: bert @ 2001-02-01 21:06 UTC (permalink / raw)
To: lartc
<PRE>On Thu, Feb 01, 2001 at 01:49:11PM -0600, fabian1 wrote:
><i> Hola lartc,
</I>><i> I have redhat6.2 (kernel 2.2.14), and ipchains.
</I>><i> I try to configure 2 default gw:
</I>><i>
</I>><i> route add default gw 200.10.0.254
</I>><i> route add default gw 205.1.0.254 metric 10
</I>><i>
</I>><i> but when gateway 1 down (lost connection) the default route didn't
</I>><i> change to the 2nd gateway. I need any servicice to do this?
</I>
Linux is supposed to have something called 'dead gateway detection' - in
what way is 200.10.0.254 'dead'? Does it still respond to ARP request?
Regards,
bert hubert
--
PowerDNS Versatile DNS Services
Trilab The Technology People
'SYN! .. SYN|ACK! .. ACK!' - the mating call of the internet
</PRE>
^ permalink raw reply [flat|nested] 8+ messages in thread* [LARTC] 2 default gw in redhat 6.2
2001-02-01 19:49 [LARTC] 2 default gw in redhat 6.2 fabian1 fabian1
2001-02-01 21:06 ` bert
@ 2001-02-01 21:18 ` Arthur
2001-02-01 21:29 ` Rene
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: Arthur @ 2001-02-01 21:18 UTC (permalink / raw)
To: lartc
<PRE>On Thu, 1 Feb 2001, bert hubert wrote:
><i> On Thu, Feb 01, 2001 at 01:49:11PM -0600, fabian1 wrote:
</I>><i> > Hola lartc,
</I>><i> > I have redhat6.2 (kernel 2.2.14), and ipchains.
</I>><i> > I try to configure 2 default gw:
</I>><i> >
</I>><i> > route add default gw 200.10.0.254
</I>><i> > route add default gw 205.1.0.254 metric 10
</I>><i> >
</I>><i> > but when gateway 1 down (lost connection) the default route didn't
</I>><i> > change to the 2nd gateway. I need any servicice to do this?
</I>><i>
</I>><i> Linux is supposed to have something called 'dead gateway detection'
</I>
Which it doesn't use when there's a multipath default route. Now, that isn't
technically the case here, so that shouldn't be the problem here.
However, I thought I'd mention it, as others might run into it.
Doei, Arthur.
--
/\ / | <A HREF="mailto:arthurvl@sci.kun.nl">arthurvl@sci.kun.nl</A> | Work like you don't need the money
/__\ / | A friend is someone with whom | Love like you have never been hurt
/ \/__ | you can dare to be yourself | Dance like there's nobody watching
</PRE>
^ permalink raw reply [flat|nested] 8+ messages in thread* [LARTC] 2 default gw in redhat 6.2
2001-02-01 19:49 [LARTC] 2 default gw in redhat 6.2 fabian1 fabian1
2001-02-01 21:06 ` bert
2001-02-01 21:18 ` Arthur
@ 2001-02-01 21:29 ` Rene
2001-02-01 21:35 ` Arthur
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: Rene @ 2001-02-01 21:29 UTC (permalink / raw)
To: lartc
<PRE>On Thu, 1 Feb 2001, Arthur van Leeuwen wrote:
><i> On Thu, 1 Feb 2001, bert hubert wrote:
</I>><i>
</I>><i> > Linux is supposed to have something called 'dead gateway detection'
</I>><i>
</I>><i> Which it doesn't use when there's a multipath default route. Now, that isn't
</I>><i> technically the case here, so that shouldn't be the problem here.
</I>
Does this mean that Linux automatically detects a failed default route and takes
the second one if I configure two default routes?
Cheers,
René
GNU/Linux Manages! - Linux Solution Provider
RP551296-NICAT - Open Software for Open Minds
</PRE>
^ permalink raw reply [flat|nested] 8+ messages in thread* [LARTC] 2 default gw in redhat 6.2
2001-02-01 19:49 [LARTC] 2 default gw in redhat 6.2 fabian1 fabian1
` (2 preceding siblings ...)
2001-02-01 21:29 ` Rene
@ 2001-02-01 21:35 ` Arthur
2001-02-01 23:07 ` Rene
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: Arthur @ 2001-02-01 21:35 UTC (permalink / raw)
To: lartc
<PRE>On Thu, 1 Feb 2001, Rene 'Lynx' Pfeiffer wrote:
><i> On Thu, 1 Feb 2001, Arthur van Leeuwen wrote:
</I>><i>
</I>><i> > On Thu, 1 Feb 2001, bert hubert wrote:
</I>><i> >
</I>><i> > > Linux is supposed to have something called 'dead gateway detection'
</I>><i> >
</I>><i> > Which it doesn't use when there's a multipath default route. Now, that isn't
</I>><i> > technically the case here, so that shouldn't be the problem here.
</I>><i>
</I>><i> Does this mean that Linux automatically detects a failed default
</I>><i> route and takes the second one if I configure two default routes?
</I>
No, it means the exact opposite. If you configure two default routes
Linux will randomly multiplex outgoing connections over the two routes.
As opposed to the case of a single route it will not even *try* to do
dead gateway detection on these routes anymore. Yes, I do think that
behaviour is silly. However, I haven't thought of a better way to do
it yet.
Doei, Arthur.
--
/\ / | <A HREF="mailto:arthurvl@sci.kun.nl">arthurvl@sci.kun.nl</A> | Work like you don't need the money
/__\ / | A friend is someone with whom | Love like you have never been hurt
/ \/__ | you can dare to be yourself | Dance like there's nobody watching
</PRE>
^ permalink raw reply [flat|nested] 8+ messages in thread* [LARTC] 2 default gw in redhat 6.2
2001-02-01 19:49 [LARTC] 2 default gw in redhat 6.2 fabian1 fabian1
` (3 preceding siblings ...)
2001-02-01 21:35 ` Arthur
@ 2001-02-01 23:07 ` Rene
2001-02-02 9:32 ` Arthur
2001-02-02 13:44 ` Paul
6 siblings, 0 replies; 8+ messages in thread
From: Rene @ 2001-02-01 23:07 UTC (permalink / raw)
To: lartc
<PRE>On Thu, 1 Feb 2001, Arthur van Leeuwen wrote:
><i> On Thu, 1 Feb 2001, Rene 'Lynx' Pfeiffer wrote:
</I>><i>
</I>><i> > On Thu, 1 Feb 2001, Arthur van Leeuwen wrote:
</I>><i> >
</I>><i> > > On Thu, 1 Feb 2001, bert hubert wrote:
</I>><i> > >
</I>><i> > > > Linux is supposed to have something called 'dead gateway detection'
</I>><i> > >
</I>><i> > > Which it doesn't use when there's a multipath default route. Now, that isn't
</I>><i> > > technically the case here, so that shouldn't be the problem here.
</I>><i> >
</I>><i> > Does this mean that Linux automatically detects a failed default
</I>><i> > route and takes the second one if I configure two default routes?
</I>><i>
</I>><i> No, it means the exact opposite. If you configure two default routes
</I>><i> Linux will randomly multiplex outgoing connections over the two routes.
</I>
This is exactly the problem I am having. I am trying to set up a spare default
route in case the primary route is down. The router in question is a Linux
machine having access to three upstream connections and to the DMZ. I do not
want to have routing daemons on the box, I simply want to change the default
route in case the primary connection (which supplies the LAN behind the DMZ) is
down.
The only thing I have come up so far (I do not want to have fancy things like
zebra, routed or gated on this machine) is a Perl script that measures the
connectivity and takes action if it detects that the route is down.
Does anyone have a better idea? (I am willing to to a nice and tidy ASCIIgram
if you like ;-)
Cheers,
René
GNU/Linux Manages! - Linux Solution Provider
RP551296-NICAT - Open Software for Open Minds
</PRE>
^ permalink raw reply [flat|nested] 8+ messages in thread* [LARTC] 2 default gw in redhat 6.2
2001-02-01 19:49 [LARTC] 2 default gw in redhat 6.2 fabian1 fabian1
` (4 preceding siblings ...)
2001-02-01 23:07 ` Rene
@ 2001-02-02 9:32 ` Arthur
2001-02-02 13:44 ` Paul
6 siblings, 0 replies; 8+ messages in thread
From: Arthur @ 2001-02-02 9:32 UTC (permalink / raw)
To: lartc
<PRE>On Fri, 2 Feb 2001, Rene 'Lynx' Pfeiffer wrote:
><i> On Thu, 1 Feb 2001, Arthur van Leeuwen wrote:
</I>><i>
</I>><i> > On Thu, 1 Feb 2001, Rene 'Lynx' Pfeiffer wrote:
</I>><i> >
</I>><i> > > On Thu, 1 Feb 2001, Arthur van Leeuwen wrote:
</I>><i> > >
</I>><i> > > > On Thu, 1 Feb 2001, bert hubert wrote:
</I>><i> > > >
</I>><i> > > > > Linux is supposed to have something called 'dead gateway detection'
</I>><i> > > >
</I>><i> > > > Which it doesn't use when there's a multipath default route. Now, that isn't
</I>><i> > > > technically the case here, so that shouldn't be the problem here.
</I>><i> > >
</I>><i> > > Does this mean that Linux automatically detects a failed default
</I>><i> > > route and takes the second one if I configure two default routes?
</I>><i> >
</I>><i> > No, it means the exact opposite. If you configure two default routes
</I>><i> > Linux will randomly multiplex outgoing connections over the two routes.
</I>><i>
</I>><i> This is exactly the problem I am having. I am trying to set up a spare default
</I>><i> route in case the primary route is down. The router in question is a Linux
</I>><i> machine having access to three upstream connections and to the DMZ. I do not
</I>><i> want to have routing daemons on the box, I simply want to change the default
</I>><i> route in case the primary connection (which supplies the LAN behind the DMZ)
</I>><i> is down.
</I>
><i> The only thing I have come up so far (I do not want to have fancy things like
</I>><i> zebra, routed or gated on this machine) is a Perl script that measures the
</I>><i> connectivity and takes action if it detects that the route is down.
</I>
><i> Does anyone have a better idea? (I am willing to to a nice and tidy ASCIIgram
</I>><i> if you like ;-)
</I>
Nope. Polling for connectivity is what you're stuck with doing, unless you
want to do some kernel hacking.
Doei, Arthur. (Who is thinking about actually doing the latter... it's
*useful*, in more cases than one)
--
/\ / | <A HREF="mailto:arthurvl@sci.kun.nl">arthurvl@sci.kun.nl</A> | Work like you don't need the money
/__\ / | A friend is someone with whom | Love like you have never been hurt
/ \/__ | you can dare to be yourself | Dance like there's nobody watching
</PRE>
^ permalink raw reply [flat|nested] 8+ messages in thread* [LARTC] 2 default gw in redhat 6.2
2001-02-01 19:49 [LARTC] 2 default gw in redhat 6.2 fabian1 fabian1
` (5 preceding siblings ...)
2001-02-02 9:32 ` Arthur
@ 2001-02-02 13:44 ` Paul
6 siblings, 0 replies; 8+ messages in thread
From: Paul @ 2001-02-02 13:44 UTC (permalink / raw)
To: lartc
<PRE>On Fri, 2 Feb 2001, Arthur van Leeuwen wrote:
><i> Nope. Polling for connectivity is what you're stuck with doing, unless you
</I>><i> want to do some kernel hacking.
</I>
I'm not too familiar with the latest kernel netfilter capabilities, but
is it possible to MARK certain packet (eg retransmits) so that they could
be caught by the netlink device which sends them to a userspace program,
which changes the default route?
Or could you mark ICMP destination unreachables to fling them up the
netlink chain into userspace?
Paul Wouters
Xtended Internet
--
Broerdijk 27 Postbus 170 Tel: 31-24-360 39 19
6523 GM Nijmegen 6500 AD Nijmegen Fax: 31-24-360 19 99
The Netherlands The Netherlands <A HREF="mailto:info@xtdnet.nl">info@xtdnet.nl</A>
</PRE>
^ permalink raw reply [flat|nested] 8+ messages in thread