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New Member

CSS UDP source group sticky problem

I have a CSS 11503 that we use to balance SIP calls(UDP) among our SIP servers.

We have a content rule that balances the incoming traffic and a source group to NAT the outbound traffic. Both the content rule and the source group use the same IP address.

When a SIP call arrives at one of our servers through the VIP an entry is created in the sticky table based on the sip-call-id as expected. But when we initiate a call from one of our SIP servers an entry is not created in the sticky table. When the remote SIP server responds the CSS sees a new sip-call-id and load balances the call instead of sending it back to the originating server.

Is there a way to add an entry to the sticky table for the sip-call-id when a source group is used?

Here is the pertinent config:

circuit VLAN2

  ip address

    ip virtual-router 25

    ip redundant-interface 25

    ip redundant-vip 25

    no redirects

circuit VLAN3

  ip address

    ip virtual-router 52

    ip redundant-interface 52

    no redirects

service SIP03

  ip address

  redundant-index 130


service SIP08

  ip address

  redundant-index 180

owner test

  content sip-udp-test

    application sip

    port 5060

    protocol udp

    flow-timeout-multiplier 38

    vip address

    redundant-index 103

    balance weightedrr

    add service TalkingSIP03 weight 1

    add service TalkingSIP08 weight 1

    advanced-balance sip-call-id


!*************************** GROUP ***************************

group sip-udp-test

  vip address

  flow-timeout-multiplier 38

  redundant-index 200

  add service SIP03

  add service SIP08

  portmap disable

A call comes into on udp 5060, is load balanced to, and an entry is added to the sticky-table for the sip-call-id.

When SIP03 starts a call to remote server using source group IP a sticky-table entry is not added for the sip-call-id and when sends a response it is load balanced to either SIP03 or SIP08.

How can I keep the call that was initiated on SIP03 on SIP03?



Everyone's tags (5)

CSS UDP source group sticky problem


  The "vip address" on your content rule is what matches the inbound traffic.  Your outbound traffic is initiated to which is not a vip ip, hence, it doesn't match the content rule.  On the reverse - the response is mapping to a vip ip since the source was the natpool.  I would assume that server already had a connection through the vip and/or something changed slightly about the flow that classified it as a new inbound connection instead of re-mapping back through the sourcenat pool. 


New Member

CSS UDP source group sticky problem

I think this problem is unique to UDP.

I assume there is an existing flow with the sourcenat when responds. Is there a way get the CSS to use the flow in this instance instead of load balancing?

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