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boo_radley_1114's avatar
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Jul 12, 2011

Possible to dedicate interfaces in a single VLAN?

Here is my situation: I have a single /24 test network and a single VLAN defined on my F5 LTM called 'internal'. Clients, virtual servers, pool members, etc, are all on the same network, so I was only using a single interface on the LTM.



However, as we increased test traffic, we started seeing throughput rates of 700-800 Mbps on this single interface, and signs of network latency (eg, fetch times for a static image). So as an immediate work-around, I created a 'trunk' on the LTM side, by connecting a second interface back to the switch, and used LACP, and the network admins configured whatever they needed to on the Cisco 2960 switch. In theory I now have 2Gbps bandwidth....



I'm still not happy with this topology, and I'd like to have client traffic enter on one set of trunked interfaces (say 1.1. and 1.2) and traffic from the load-balanced servers back to the client on another trunk: say interfaces (1.3. and 1.4). Is it possible to do this on a single VLAN? The alternative is to create a second VLAN for the client traffic, which makes sense, but it's hard to implement at the moment because client and server test machines are intermingled so it's very difficult assigning different ports in the network switches to a specific vlans.







2 Replies

  • Hi Boo,



    I think the simplest solution would be to add more ports to a single trunk. You could try VLAN groups for this, but it's a messy solution. The most common implementation is to create separate VLANs for client and server hosts.



  • hoolio as an expert is of course right :)


    what I suggest to you is to check weather this traffic rate is generated only by your servers. I mean weather there are no drops on interfaces on swith or F5. Once I had this situation that traffic on trunk (LACP) was huge and only one service was turned on. A lot of drops were seen on the interfaces of F5. For me it was a new situation and pain in the a... and what we found out was that administrator of the switch forgot to limit trunk to only allowed vlans, and all traffic was sent to this LACP ports which F5 did drop cause it was listening only on its specified vlans.