ARCH wait on SENDREQ

I have DG set up for my DBs and contantly I got high "ARCH wait on SENDREQ". If I understand correctly, Oracle had 2 achiver by default: so one of them archiver the data and other archiver sent the log over the the stand by. So if I have "ARCH wait on SENDREQ", does it mean that I have some bottleneck on my network when the second archiver sent off the log?

1. if my network slow which leads to "ARCH wait on SENDREQ" and it result the database performance, am I correct?

2. by default, Oracle had 2 archiver and I won't if they are depended on each other? Another word, if the second is not finsihed sending the log over to DR, does it mean the first one will wait till the second one finish its job.

Thanks,

This is most likely caused by slow network connection in between sites; a poorly performing storage subsystem on secondary location could also cause this wait event.
Check metalink Note ID 418709.1 for details.