bgp require in multigateway routing

[sonu chouhan]

hi all,
first i wann to explain my network & it's problem,
i am using a redhat el5 for multigateway routing, i have 3 adsl lines which is connected with eth0, eth2 and eth3. eth1 is my local network.
those 3 lines comes with adsl modem from same isp with equal bandwidth (512 Kbps).
In this adsl modems there is one lan and one wan port, adsl modem's lan ip is gateway for my linux box, some times wan port of the modem got hang and that time lan ip of modem does up and accessable, so for my linux box gateway is up but internet is down of this gateway, but linux box seem this like running gateway and it's continusly send request to this gateway,
so that time failover routing not work, so i need it's solution.
somebody suggest me to use border gateway protocol for this, but i don't have any knowledge about this protocol that it will useful for me our not, and plz also guide me how to configure this protocol.

sorry for my poor english

thanks in advance

sonu


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[Radek 'Goblin' Pieczonka]

Post by sonu chouhan
somebody suggest me to use border gateway protocol for this, but i
don't have any knowledge about this protocol that it will useful for
me our not, and plz also guide me how to configure this protocol.

considering the bandwidth, i dont think your ISP would even start to
think about BGP, not to mention the fact that as long as you use the
same ISP I'd rather think of OSPF or even RIPv2. Also, there is a
question of support on modem, as from what you say its actually a router
with adsl modem integrated, so it should take part of dynamic routing.
All in all, first question to ask is what your ISP is willing to do in
this case. As an alternative you can always run some checks on links and
switch routing information (aspecially default route, or selection of
routing table in policy routing) in static table from some cron script /
daemon accordingly.

[sonu chouhan]

Thanks a lot for your reply,
my isp doesn't support bgp, so i have a second chance to write a script for this,
but my question is, if i run a script which will detect dead route and then delete that route, all is fine but after deleting route how can i know that this route is working again and need to add it again. plz help me and if you have any script like this plz provide me.
thanks again

sonu....

Post by sonu chouhan
somebody suggest me to use border gateway protocol for this, but i
don't have any knowledge about this protocol that it will useful for
me our not, and plz also guide me how to configure this protocol.

considering the bandwidth, i dont think your ISP would even start to
think about BGP, not to mention the fact that as long as you use the
same ISP I'd rather think of OSPF or even RIPv2. Also, there is a
question of support on modem, as from what you say its actually a
router
with adsl modem integrated, so it should take part of dynamic routing.
All in all, first question to ask is what your ISP is willing to do in
this case. As an alternative you can always run some checks on links
and
switch routing information (aspecially default route, or selection of
routing table in policy routing) in static table from some cron script
/
daemon accordingly.
--
Radek aka Goblin
***@pentex.pl


------------------------------



---------------------------------
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[Grant Taylor]

Post by sonu chouhan
my isp doesn't support bgp, so i have a second chance to write a
script for this, but my question is, if i run a script which will
detect dead route and then delete that route, all is fine but after
deleting route how can i know that this route is working again and
need to add it again. plz help me and if you have any script like
this plz provide me.

I think you will want to delete the route (or mark it dead) in your
(main?) routing table that gets used by most of your traffic and leave
additional administrative / test routing tables alone. With the
additional administrative / test routing tables you can have your test
traffic go out the routes that would otherwise not be used by your
normal traffic. Thus you can have test scripts see if the routes are
good or not. If the routes are good, you can re-add the routes to your
mail (?) routing table.

Another idea is to use different routing tables based on the connection
status. I.e. have main_both, main_isp_a, and main_isp_b routing tables
that are used for your normal traffic. If something happens, just
change the routing table that is used from main_both to main_isp_<that
is still up>. Changing which routing table is used is probably going to
be easier than altering a routing table.

Just to be clear, you will still want to have test_isp_a and test_isp_b
routing tables so you can direct your test traffic to use either
connection. So all in all, this route, you will have five routing
tables: main_both, main_isp_a, main_isp_b, test_isp_a, and test_isp_b.



Grant. . . .

[Nickola Kolev]

На Thu, 13 Dec 2007 06:12:36 -0800 (PST)

Post by sonu chouhan
Thanks a lot for your reply,
my isp doesn't support bgp, so i have a second chance to write a
script for this, but my question is, if i run a script which will
detect dead route and then delete that route, all is fine but after
deleting route how can i know that this route is working again and
need to add it again. plz help me and if you have any script like
this plz provide me. thanks again sonu....

You can take a look at this document:

http://blog.taragana.com/index.php/archive/how-to-load-balancing-failover-with-dual-multi-wan-adsl-cable-connections-on-linux/

The script mentioned is working as a charm.

[ cut ]

[Manish Kathuria]

Post by sonu chouhan
Thanks a lot for your reply,
my isp doesn't support bgp, so i have a second chance to write a script for this,
but my question is, if i run a script which will detect dead route and then
delete that route, all is fine but after deleting route how can i know that
this route is working again and need to add it again. plz help me and if you
have any script like this plz provide me.
thanks again
sonu....

I had posted a script on this list early this year. You can check out
the link and use the script.

http://mailman.ds9a.nl/pipermail/lartc/2007q1/020170.html

You will have to modify it since this one is for two internet links
whereas you have three links. But I think it should be easy to do,
just the number of cases would increase. You will have to take care of
all possible scenarios (all 3 links active, any two links active and
any one link active) and set the default route for these 7 cases.