Other Line Options: Difference between revisions

[[File:Cqm-ratedrop.png|none|frame|Changing the rate from 100% to 95% reduced average latency when filling the downlink.]]

These stability options refer to how aggressiveness BT's DLM is when monitoring and managing the line.

Usually we'd suggest keeping it on Normal (the default). Using increased stability options increases DLM sensitivity, so can have the side effect of making your line sync at lower speeds.

'''More Info:''' MTU is negotiated upon connection. We usually like 1500 MTU, however, there can be situations where forcing 1492 is required. For example, if your router negotiated 1500 initially but you make a connection to a server that want's to re-negotiate a lower MTU it will try to do this using ICMP, but if your router has a miss-configured firewall that blocks ICMP this can't be re-negotiated and the connection to the server will have problems. This is seen when connecting to certain web sites, bank web sites and https sites. Forcing 1492 from the start means that all your traffic is in packets of 1492 bytes and so won't have this problem.

[[File:LineOptionsLCPFix.png|none|frame|Re-negotiates PPP LCP after acquiring the connection from BT, who may provide an MTU of 1500 when it should be 1492.]]

'''More Info:''' During the PPP connection when your router initially syncs up and logs in to us, the PPP connection is passed via BT. Sometimes BT can change the MTU. With this option we will accept the PPP connection from BT, but will then re-negotiate the PPP connection with your router allowing the MTU to be reduced. On TalkTalk connections the MTU is always negotiated as 1492, you need to select LCPFix and an MTU of 1500 to fix this, otherwise the LNS will use 1492 when re-negotiating.

Shows the recent usage/quality stats for the line, with columns:

Time,Period,Polls Sent,Fail,Latency Min,Ave,Max,Traffic (bit/s) Rx,Tx,Score

The steps are normally 100s. Latency is in ns. The output is in CSV format for ease of import into a spreadsheet.