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Cisco Expressway behind BigIP F5 LTM

Richard Dumag

We are implementing two Cisco Expressways for Jabber.  Our DMZ zone is fronted by the BigIP F5 LTM.  Instead of creating another DMZ zone just for Jabber, we would like to put the external Expressways behind the F5 (not for load balancing) instead.  Is this possible?  Has anyone done this successfully and can you share your experience and setup?  Appreciate any comments or suggestions. Thank you. 



7 Replies 7

Nithin Eluvathingal
VIP Mentor VIP Mentor
VIP Mentor

One of my customer wanted to use F5 in the front, not for load balancing but  it never worked. They spend almost three weeks and finally removed the F5.

You dont need a F5 in the expresway path.

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Thanks for the quick reply, Nithin.  But I don't want to create a firewall policy that indicates an outside to inside zone traffic.  I'm trying to avoid creating a second DMZ zone, but I guess I will have to.



Why do you need a Second DMZ ?, do the nating on Firewall. Allow the ports mentioned on the MRA guide.

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Cisco's recommendation is to place the external expressway on the DMZ.  Did your customer have their expressway NAT'ed from the inside?   If so, isn't that a little risky?

You should put the Expressway-E in a DMZ and then put the Expressway-C on the internal network. This would not be any different if you were to use F5, the network topology for an Expressway deployment stays the same. To allow traffic to your E(s) to reach the C(s) you’ll need to have a few different rules created in your firewall(s). You’ll need internet to E (external interface), E (external interface) to internet, C to E (internal interface) and management traffic to E (internal interface). If you’re using internal resources for DNS, NTP, syslog and so on you’ll need to allow the E to reach those as well.

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Roger Kallberg
VIP Expert VIP Expert
VIP Expert

We use F5 for this. It fronts our MRA systems, but aren’t in the actual traffic path, and does geoDNS for the connecting client and keeps track of the status of each E we have so that it doesn’t direct traffic to an Expressway-E that is unavailable. This works perfectly fine for our system landscape.

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Thanks Roger.  We don't have geoDNS on the F5 unfortunately.  We're looking to just put the external expressway behind the F5 instead of creating another DMZ.

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