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epaalx's avatar
epaalx
Icon for Cirrus rankCirrus
Sep 19, 2011

multiple interfaces on a single VLAN

Hello F5'ers,

 

I've taken it for granted that it just works, but was questioned by a non-F5 colleague and couldn't provide qualified answer or cite documentation....

 

"TMOS Management Guide for BIG-IP Systems", Chapter 7, section "Related configuration tasks":

 

"When you assign multiple interfaces to a single VLAN, traffic destined for a host in that VLAN can travel through any one of these interfaces to reach its destination"

 

Questions (assuming STP hadn't blocked all):

 

1. How is outgoing traffic distributed - would ARPs be sent out on both interfaces?

 

2. How is returning traffic distributed (towards Clients) when AutoLasthop is disabled?

 

3. If a multicast/broadcast arrives on one interface, would F5 forward it onto second interface?

 

Thanks.

 

config
design
  • The_Bhattman's avatar
    The_Bhattman
    Icon for Nimbostratus rankNimbostratus
    Sep 19, 2011
    Hi Epaalx,

     

    I think the following link might answer your questions regarding how trunk links forwarding packets are distributed

     

    http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/tmos_management_guide_10_0_0/tmos_trunks.html1010209

     

     

    AS for multicast the following link might be helpful

     

    http://support.f5.com/kb/en-us/solutions/public/9000/300/sol9310.html?sr=16619446

     

     

    I hope this helps

     

    Bhattman
  • epaalx's avatar
    epaalx
    Icon for Cirrus rankCirrus
    Sep 19, 2011
    Hi Bhattman,

     

    thanks, but my issue isn't with Trunks - LTM allows multiple Interfaces (multiple Trunks, too) associated with a VLAN.. The question is - how does TMM distribute outgoing traffic among the Interfaces (and Trunks)?

     

     

    Re: "3. If a multicast/broadcast arrives on one interface, would F5 forward it onto second interface?" - I think I can answer this myself - as per F5 SOL9310: "By default, LTM functions as an L2-only switch, flooding frames addressed to L2 multicast addresses across all interfaces in the VLAN but the origin." Since broadcast is a general type of multicast, then for both cases, LTM will forward them onto other interfaces.

     

     

    R's, Alex