Should I trunk?

[jdufour]

Hello!

We are reconfiguring a 20 switch network. We have HP 2920 models, all identical. We have no VLAN usage besides the default VLAN1. We are considering the pros and cons of using group trunking to connect switches. Our thought is that this may improve overall network performance. We have no data on traffic flow, bandwidth. Our IPS connection is 10 Gig capable. Should we use group trunking? If so, how many ports? Pros? Cons?  Thanks for your time! -  John

[parnassus]

Yes, you should.

There is a very primary reason: if your network topology and passive cabling permit the usage of more than just a single cable (Up to 8 ports can be aggregated per LAG Link Aggregation Group, AKA "Trunk") between each Switch (or between each Switch and its core, if a core Switch exists), then you will see (a) enhancements on network throughput (especially the any-to-one and the any-to-any traffic types) both horizontally (if your twenty switches form a long chain, which is a bad thing) and also vertically (to the core/ToR), and (b) better resiliency levels against cables/ports failures (it helps management too).

Clearly you must consider that you should (1) dedicate some ports only for Port Trunking purposes on each Switch and (2) configure port trunking groups on all involved Switch (or, at least, on those Switches you think they will require that type of deployment).

Consider that you should avoid chains and loops, preferring a star topology (a Star with a Core)...eventually, if your units aren't too far each others (are on the same rack or are on very near - distance < 3 meters - racks), you can consider to deploy backplane stacking (it's Hardware stacking) for some of them (Up to 4 members)...but all depends on your planned network topology and traffic flows (East/West and/or North/South) between your various Clients and Servers.