====== Использование двух ISP ======

  * [[http://www.anticisco.ru/blogs/2011/05/введение-в-cisco-oerpfr/|Введение в Cisco OER/PfR]]
  * [[https://habrahabr.ru/post/81424/|Немного об ip sla / rtr в Cisco…]]
===== Настройка роутера на использование двух провайдеров =====
<code>
interface FastEthernet0/0
 description connect to ISP2
 duplex full
 ip address 172.16.2.X 255.255.255.0
 ip nat outside
 no shutdown

ip name-server 172.16.2.254

ip access-list standard ACL_REDIRECT_ISP1
 permit 192.168.X.0 0.0.0.255
ip access-list standard ACL_REDIRECT_ISP2
 permit 192.168.100+X.0 0.0.0.255

no ip nat inside source list ACL_NAT interface FastEthernet1/1 overload

ip nat inside source list ACL_REDIRECT_ISP1 interface FastEthernet1/1 overload

ip nat inside source list ACL_REDIRECT_ISP2 interface FastEthernet0/0 overload

route-map RM_REDIRECT_ISP permit 10
 match ip address ACL_REDIRECT_ISP1
 set ip next-hop 172.16.1.254
!
route-map RM_REDIRECT_ISP permit 20
 match ip address ACL_REDIRECT_ISP2 
 set ip next-hop 172.16.2.254

interface FastEthernet1/0
 ip policy route-map RM_REDIRECT_ISP
</code>

===== Переключение каналов =====

==== Фрагменты конфигураций роутера ====

=== Доступны оба ISP ===
<code>
server# cat isp1_isp2.cfg
</code><code>
no ip access-list standard ACL_REDIRECT_ISP1
no ip access-list standard ACL_REDIRECT_ISP2
ip access-list standard ACL_REDIRECT_ISP1
 permit 192.168.X.0 0.0.0.255
 deny any
ip access-list standard ACL_REDIRECT_ISP2
 permit 192.168.100+X.0 0.0.0.255
 deny any
end
</code>
=== Доступен ISP1 ===
<code>
server# cat isp1.cfg
</code><code>
no ip access-list standard ACL_REDIRECT_ISP1
no ip access-list standard ACL_REDIRECT_ISP2
ip access-list standard ACL_REDIRECT_ISP1
 permit 192.168.X.0 0.0.0.255
 permit 192.168.100+X.0 0.0.0.255
ip access-list standard ACL_REDIRECT_ISP2
 deny any
end
</code>
=== Доступен ISP2 ===
<code>
server# cat isp2.cfg
</code><code>
no ip access-list standard ACL_REDIRECT_ISP1
no ip access-list standard ACL_REDIRECT_ISP2
ip access-list standard ACL_REDIRECT_ISP1
 deny any
ip access-list standard ACL_REDIRECT_ISP2
 permit 192.168.X.0 0.0.0.255
 permit 192.168.100+X.0 0.0.0.255
end
</code>


==== Переключение в ручном режиме ====
<code>
cat /etc/resolv.conf
</code><code>
...
nameserver 172.16.1.254
nameserver 172.16.2.254
</code><code>
cat /etc/hosts
</code><code>
...
192.168.X.1     router
</code><code>
server# rcp isp1.cfg router:running-config

server# rcp isp2.cfg router:running-config

server# rcp isp1_isp2.cfg router:running-config

server# rsh router "clear ip nat tr *"
</code>

==== Тестирование провайдеров с роутера ====
<code>
server# cat route_isp1.cfg
</code><code>
no ip route 0.0.0.0 0.0.0.0 172.16.2.254
ip route 0.0.0.0 0.0.0.0 172.16.1.254
end
</code><code>
server# cat route_isp2.cfg
</code><code>
no ip route 0.0.0.0 0.0.0.0 172.16.1.254
ip route 0.0.0.0 0.0.0.0 172.16.2.254
end
</code><code>
server# rcp route_isp1.cfg router:running-config
server# rsh router ping ya.ru

server# rcp route_isp2.cfg router:running-config
server# rsh router ping ya.ru
</code>

==== Автоматизация переключения на резервный канал ====

<code>
server# cat select_isp.sh
</code><code>
#!/bin/sh

touch /tmp/conf_name

rcp /root/route_isp1.cfg router:running-config
rsh router ping ya.ru | grep -q '!'
ALIVE1=$?

rcp /root/route_isp2.cfg router:running-config
rsh router ping ya.ru | grep -q '!'
ALIVE2=$?

test $ALIVE1 -eq 0 && conf_name="isp1.cfg"
test $ALIVE2 -eq 0 && conf_name="isp2.cfg"
test $ALIVE1 -eq 0 && test $ALIVE2 -eq 0 && conf_name="isp1_isp2.cfg"

# echo /root/$conf_name
# exit 0

test $conf_name = "`cat /tmp/conf_name`" && exit 0

echo $conf_name > /tmp/conf_name

rcp /root/$conf_name router:running-config

rsh router "clear ip nat tr *"

exit 0
</code><code>
server# chmod +x select_isp.sh

server# echo isp1_isp2.cfg > /tmp/conf_name

server# crontab -e
</code><code>
*/5 * * * * /root/select_isp.sh
</code>