Less Than Best Effort on GÉANT2
The Less Than Best Effort (LBE) service has been implemented on GÉANT2 at the request of NRENs, researchers and GRID projects. It provides a traffic class that is able to make use of unused bandwidth on the GÉANT2 network. It allows high volume, low priority applications to run in the available bandwidth without adversely affecting regular Best Effort and Premium IP traffic.
LBE traffic is allocated any bandwidth not used by Premium IP and Best Effort services. If the network becomes congested, Premium IP and Best Effort traffic will take precedence – LBE packets are always the first to be dropped. LBE traffic is therefore subject to a relatively high risk of packet loss.
It may seem odd that anyone would want to use such a service. However, it is particularly useful for researchers who need to ship huge amounts of data where the speed of transfer is not so important, or where they do not want to risk affecting Best Effort or Premium IP traffic from other users. Some examples include:
- Data mirroring, where the mirror is updated continuously rather than once every night
- GRID data transfers, where time is not a constraint
- Non-invasive test traffic
- Network backups that need to be performed continuously throughout the day
- Student dormitory networks, which need to operate while protecting the research traffic
Requesting Less Than Best Effort
The Less Than Best Effort service on GÉANT is enabled by default, and is available at all PoPs in GÉANT2. To use it, sent packets must be tagged with DSCP 8. Any packet arriving on GÉANT with DSCP 8 is treated as Less than Best Effort.
Monitoring
The available network capacity for Less Than Best Effort traffic is currently monitored for each link by a tool called Taksometro. A traceroute with TOS (DSCP) change detection is available, but this tool is only available to those with NREN access port managers (APM) privileges.
Service Level Agreement
No end-to-end guarantees are provided to flows adopting the LBE service. This means that the LBE service is not parameterized - no performance metrics are needed to quantitatively describe the service. Because of this, there is no specific Service Level Agreement for LBE.
Note however, that this does not mean that any problems experienced by LBE users will be overlooked. In the event of problems, the network operators will be thoroughly investigated and the user will be notified of the cause. If the problem is caused by something other than congestion, it will be treated as per the Best Effort service.
