High availability from SW - Router


We are giving a Network design to one of my customer..

Pls view very clearly of Topology  diagram and here is a brief description :

1.Two Core-Switches : SW-A and SWB
2. Between Core-Sw-A and Core-Sw B implemeted HSRP protocl for redundancy
3. Firewall-A and Firewall B both are Active-Active
4.Router-A and Router-B both are acttive-Active.
5.ISP-A and ISP-B

Requirement :

1.VLAN 10 traffic should go via Sw-A to FW-A to  Router-A to  ISP-A
2.VLAN 20 traffic should go via Sw-B to FW-B to Router-B to ISP-B..

If any link failure happens the effected traffic should pass over active links..

My queries are :

1.Can we give design where both ASA firewall are in Active-Active or it should be active / standby.What will happen if it is Active/Active..

2. How router translated one  ISP NAT entry to other ISP NAT entry for the same source ip address..

3, is there any need for zone based firewall configuraiton  on Router-A and RouterB., if yes pls share the inputs on Zone based firewall configuration.

Till Switches configuration , i can do . will you pls give the configuration of
Firewalls and Routers

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RAMU CHAuthor Commented:

I have gone through the ASA Active / Active failover scenario.. I hope i will be helpful
to my scenario..

What woul;d be the Routers Router-A and Router-B configurations

RAMU CHAuthor Commented:
Can we apply HSRP protocol  on Routers which are connnected to ISP, is it recommendable or  any design considerations?

WIll it be applicable for my scenario, which as attached?

ffleismaSenior Network EngineerCommented:
2. How router translated one  ISP NAT entry to other ISP NAT entry for the same source ip address..

Since you are using two different ISP, they'll probably assign you different IP blocks, in which case your active-active scenario won't be possible. during failover, traffic will be NATed to a different public IP hence, disconnection will be experienced.

one solution for this is that the client "owns" the public IP block and both ISP is advertising the same public IP block. in this case, failover or lose of one ISP link will have very minimal impact or minor flapping of connection as routing converged. even in this scenario, you should consider using a load balancer. but to be honest, full utilization of internet link by load balancing is very hard and complicated to achieve. even using load balancers such as f5 or radware, just balances the load depending on how it is configured (source-destination, preference, etc - meaning, its dependent on the manual configuration of the load balancer)

1.Can we give design where both ASA firewall are in Active-Active or it should be active / standby.What will happen if it is Active/Active..

active-active ASA setup is a bit tricky. As you may be aware, ASA are stateful firewalls, meaning a connection made in one active state might be interrupted during failover since the state is not existing on the other active firewall and needs to be rebuilt again.  think of active-active ASA as two separate physical FW. if one firewall fails, then the other FW takes over, but in these case, it needs to rebuild the connections already established on the failed FW which can cause application disconnection or flapping. generally it is best to stick with active-standby setup for ASA.

also consider that FW-internet router connections are still generally part of the LAN (or DMZ) which still uses 1gig connections, having both ASA in active-active doesn't give much incentive in terms of dividing traffic or utilization.

generally in my experience, active-active ASA is only done to accommodate separating two networks in different virtual context. Client A uses virtual context A (active-standby), client B uses virtual context B (standby-active). hence active-active here, is useful, since we didn't need to bring additional hardware and provided active-standby FW on separate clients.

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RAMU CHAuthor Commented:
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