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=======Configuration of fault tolerance switching between 2 ISP and NAT for Internal network on the Juniper SRX 220H cluster and Cisco 1941=======
 ==== Introduction. ====

We have 2 ISP and internal network with INTERNAL_NET/24.\\
**Task**:\\ configure on the Juniper SRX 220H and Cisco 1941 NAT for internal network and fault tolerance switching  between ISPs.\\

{{:ru:jobs:2ispnat.jpg?700|700}}


 
 ==== Solution for Juniper SRX 220H Cluster.  ====

1. Requirements: **%%JunOs%% verion 11 or above**\\

2. Configure two security zones on the Juniper:\\
  
  {primary:node1}[edit]
  set security zones security-zone ISPs interfaces reth0.0
  set security zones security-zone ISPs interfaces reth1.0
    
  set security zones security-zone Internal interfaces reth2.0
  set security zones security-zone Internal address-book address INTERNAL_NET INTERNAL_NET/24
 

3. Configure security policies\\ 
  
  {primary:node1}[edit]
  set security policies from zone Internal to zone ISPs policy Internal_to_ISPs match source-address INTERNAL_NET 
  set security policies from zone Internal to zone ISPs policy Internal_to_ISPs match destination-address any 
  set security policies from zone Internal to zone ISPs policy Internal_to_ISPs match application any 
  set security policies from zone Internal to zone ISPs policy Internal_to_ISPs then permit

4. Configure static routing.

  {primary:node1}[edit]
  set routing-options static route 0.0.0.0/0 next-hop IP_DG_ISP-1
  set routing-options static route 0.0.0.0/0 qualified-next-hop IP_DG_ISP-2 preference 100

5. Configure monitoring of ISPs. We will monitor default gateways for this example.

   {primary:node1}[edit]
   set services rpm probe First_ISP-Probe test First_ISP_GW target address IP_DG_ISP-1
   set services rpm probe First_ISP-Probe test First_ISP_GW probe-count 10
   set services rpm probe First_ISP-Probe test First_ISP_GW probe-interval 5
   set services rpm probe First_ISP-Probe test First_ISP_GW test-interval 10
   set services rpm probe First_ISP-Probe test First_ISP_GW thresholds successive-loss 10
   set services rpm probe First_ISP-Probe test First_ISP_GW thresholds total-loss 5
   set services rpm probe First_ISP-Probe test First_ISP_GW destination-interface reth0.0
   set services rpm probe First_ISP-Probe test First_ISP_GW next-hop IP_DG_ISP-1
   set services rpm probe Second_ISP-Probe test Second_ISP-Probe_GW target address IP_DG_ISP-2
   set services rpm probe Second_ISP-Probe test Second_ISP-Probe_GW probe-count 10
   set services rpm probe Second_ISP-Probe test Second_ISP-Probe_GW probe-interval 5
   set services rpm probe Second_ISP-Probe test Second_ISP-Probe_GW test-interval 10
   set services rpm probe Second_ISP-Probe test Second_ISP-Probe_GW thresholds successive-loss 10
   set services rpm probe Second_ISP-Probe test Second_ISP-Probe_GW thresholds total-loss 5
   set services rpm probe Second_ISP-Probe test Second_ISP-Probe_GW destination-interface reth1.0
   set services rpm probe Second_ISP-Probe test Second_ISP-Probe_GW next-hop IP_DG_ISP-2
   set services ip-monitoring policy First_ISP-Tr match rpm-probe First_ISP-Probe
   set services ip-monitoring policy First_ISP-Tr then preferred-route route 0.0.0.0/0 next-hop IP_DG_ISP-2
   set services ip-monitoring policy Second_ISP-tr match rpm-probe Second_ISP-Probe
   set services ip-monitoring policy Second_ISP-tr then preferred-route route 0.0.0.0/0 next-hop IP_DG_ISP-1


6. Configure NAT
  
  {primary:node1}[edit]
  set security nat source rule-set From_Internal_to_ISPs from zone Internal
  set security nat source rule-set From_Internal_to_ISPs to zone ISPs
  set security nat source rule-set From_Internal_to_ISPs rule NAT_INTERNAL match source-address INTERNAL_NET/24
  set security nat source rule-set From_Internal_to_ISPs rule NAT_INTERNAL then source-nat interface
  

7. Commit

  {primary:node1}[edit]
  commit
  
==== Solution for Cisco 1941. ====
 
1. Requirements:  **cisco ios version 15 with DATA licence**\\


2. At first we need to configure dotq1 on first interface because we have only two physical interface on the cisco 1941 (without extended modules).Also we will need a switch with dotq1 support. Both ISPs should be connected to a switch.\\
  
  conf t
  int gi 0/0.1 
  description First_Provider
  encapsulation dot1Q 1
  exit
  int gi 0/0.2
  description Second_Provider
  encapsulation dot1Q 2
  end
  
  

Don't forget to configure IP addresses on above mention interfaces
  
  conf t
  int gi 0/1
  descriptions Internal Network
  exit
  
3. Configure monitoring

  conf t
  ip sla 1
  icmp-echo IP_DG_ISP-1 source-interface GigabitEthernet0/0.1
  timeout 2000
  threshold 2000
  frequency 3
  exit
  ip sla schedule 1 life forever start-time now
  ip sla 2
  icmp-echo IP_DG_ISP-2 source-interface GigabitEthernet0/0.2
  timeout 2000
  threshold 2000
  frequency 3
  exit
  ip sla schedule 2 life forever start-time now
  end

4. Configure track

4. Конфигурация track

  conf t
  track 1 rtr 1 reachability
  delay down 60 up 30
  exit
  track 2 rtr 2 reachability
  delay down 60 up 30
  end


5. Configure routing.

   conf t
   ip route 0.0.0.0 0.0.0.0 IP_DG_ISP-1 track 1
   ip route 0.0.0.0 0.0.0.0 IP_DG_ISP-2 10 track 2
   end


6. Configure NAT
  
  conf t
  int gi 0/0.1
  ip nat outside
  exit
  int gi 0/0.2
  ip nat outside
  exit
  int gi 0/1
  ip nat inside
  exit
  
  ip access-list 99 permit INTERNAL_NET 0.0.0.255
  ip nat inside ip nat inside source list 99 interface gigabitEthernet 0/0.1 overload
  ip nat inside ip nat inside source list 99 interface gigabitEthernet 0/0.2 overload 
  end
  
7. Create scripts for cleaning of NAT-table and reporting to syslog. 
  
  conf t
  scheduler allocate 20000 1000
  event manager directory user policy flash:/tcl
  event manager applet ISP_1_DOWN 
  event syslog pattern "%TRACKING-5-STATE.*1 rtr 1 reachability Up->Down"
  action 1.0 cli command "enable"
  action 1.1 cli command "clear ip nat translation *"
  exit
  event manager applet ISP_1_UP 
  event syslog pattern "%TRACKING-5-STATE.*1 rtr 1 reachability Down->Up"
  action 1.0 cli command "enable"
  action 1.1 cli command "clear ip nat translation *"
  exit 
  event manager applet ISP_2_DOWN 
  event syslog pattern "%TRACKING-5-STATE.*2 rtr 2 reachability Up->Down"
  action 1.0 cli command "enable"
  action 1.1 cli command "clear ip nat translation *"
  exit
  event manager applet ISP_2_UP 
  event syslog pattern "%TRACKING-5-STATE.*2 rtr 2 reachability Down->Up"
  action 1.0 cli command "enable"
  action 1.1 cli command "clear ip nat translation *"
  end
  
8. Save configuration

  wr