Forum Discussion

BaltoStar_12467's avatar
Sep 10, 2013

difference between self-ip and internal-facing vip

f5 BIG-IP LTM VE 11.4.0

 

Could someone please describe the difference between a self-ip assigned to an internally-facing vlan , and a virtual server on the same subnet as that vlan ?

 

4 Replies

  • nathe's avatar
    nathe
    Icon for Cirrocumulus rankCirrocumulus

    A virtual server is an IP address plus port e.g. 80. A self IP is associated to a vlan/interface and how the traffic gets to the hosts on that vlan. Hope that's a useful explanation. N

     

  • nathe's avatar
    nathe
    Icon for Cirrocumulus rankCirrocumulus

    Not necessarily, depends on where the f5 sits in your network. If using snat on the vs then that could be the case. This will explain better than I can:http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/tmos-concepts-11-4-0/13.htmlconceptid

     

  • There is a good solution on AskF5 on this subject. Please check SOL3475 for details.

     

    A self IP is beeing used as:

     

    • next hop to locally attached networks (local routing tables are automatically based on it),* source IP for healthchecks (both machines in a device group will use them to send out monitors),
    • if defined as a floating self IP it may act as a next hop for incoming datagrams to get routed to destinations on or behind the BIG-IP,
    • may be used for inband management and serves as reference point for heartbeat, mirroring and config sync (make sure to disable unnecessary services via PortLockDown),
    • can be reached from associated ingress VLAN only,
    • in case of 'self IP' will belong to traffic group 'traffic-group-local-only' and never be moved to another device in the group,
    • in case of 'floating self IP' will belong to a traffic group i.e. 'traffic-group-1' along with some virtual addresses and can be moved between devices,
    • will be stored in /config/bigip_base.conf or in /config//bigip_base.conf.

    Instead a virtual server acts as a reference point to handle traffic:

     

    • on all enabled / not disabled VLANs,* depending on assigned protocol, destination IP or network address, assigned profiles, iRules and pools,
    • may get reached through a self IP which acts as next hop in case the virtual IP is not associated with the IP address range of the ingress VLAN,
    • will be stored in /config/bigip.conf or in /config//bigip.conf