Rservers initiated traffic not sourcing the traffic as VIP in Ace 4710

Question

One of the feature of our application is that our Application Server initiate text message to our devices sourcing from UDP 1120 and device need to see the message come from a specific pubic IP (2.2.2.2) with UDP port 1120 and reply back with the same Public IP (2.2.2.2) with UDP port 1120.The problem is we can make that happen if we have only one server in our ACE Serverfarm when we do a SNAT the real servers with the VIP address (10.1.246.32) but it does not work when we have more than one server in the Serverfarm. Since we have 2 servers, i cannot nat the real servers with the VIP address, if I do a PAT, obviously it is changing the source port of the request.
Note: This setup is working fine with the Cisco Content Switch module running on chasis 6509. When I sniff the traffic initiated from the server coming the CSM load balancer, it is sourcing the traffic as the VIP and the source port remains the same by default but this is not the case with ACE 4710
Traffic flow as follows
===============
ACE 4710                                                       FWSM (Firewall static NAT)                    Device ( configured with 2.2.2.2:1120 (udp) to snd/rcv msg)
                                             VIP
Rserver 1   - 10.1.104.80       10.1.246.32           10.1.246.32  < - > 2.2.2.2                              1.1.1.1
Rserver 2   - 10.1.104.81c
---------------------------------------------------------->           ------------------------------->                      - traffic flow from server to the device when we send msg
Configs:
======
rserver host server1
  ip address 10.1.104.80
  inservice
rserver host server2
  ip address 10.1.104.81
  inservice
serverfarm host SFARM
  failaction purge
  probe ICMP
  rserver server1
    inservice
  rserver server2
    inservice
access-list TEST-1120 line 8 extended permit udp host 10.1.104.80 eq 1120 any
access-list TEST-1120 line 16 extended permit udp host 10.1.104.81 eq 1120 any
parameter-map type connection UDP_TIMEOUT
  set timeout inactivity 3600
sticky ip-netmask 255.255.255.255 address source STKY-SFARM
  serverfarm SFARM
  timeout 180
  replicate sticky
class-map match-all CLS-SFARM
  2 match virtual-address 10.1.246.32 udp eq 1120
class-map match-all SERVERNAT
  2 match access-list TEST-1120
policy-map type loadbalance first-match POL-SFARM
  class class-default
    sticky-serverfarm STKY-SFARM
policy-map multi-match POL-LB
class CLS-SFARM
    loadbalance vip inservice
    loadbalance policy POL-SFARM
    loadbalance vip icmp-reply active
    connection advanced-options UDP_TIMEOUT
class SERVERNAT
   nat dynamic 1 vlan 244
int vlan 244
ip address 10.1.246.2 255.255.255.0
service-policy input POL-LB
nat-pool 1 10.1.246.32 10.1.246.32 netmask 255.255.255.255
  mac-sticky enable
  no icmp-guard
no shut
interface vlan 2506
ip address 10.1.104.2 255.255.255.0
service-policy input POL-LB
  mac-sticky enable
  no icmp-guard
no shut

Answer 1

I see in CSS, they are able to nat the source ip address with VIP and port-mapping diabled. How do I implement
portmap disable in ACE 4710
Disabling Port Mapping
By default, the CSS NATs source IP addresses and PATs source ports for a configured source group. If you configure the portmap disablecommand in a source group, the CSS performs NAT on the source IP addresses but does not perform PAT on the source ports of UDP traffic that matches on that source group.
For UDP applications with high-numbered assigned ports (for example, SIP and WAP), we recommend that you preserve those port numbers by configuring destination services in source groups instead of using the portmap disable command. Destination services cause the CSS to NAT the client source ports, but not the destination ports. For information about configuring destination services,