Does anyone have a good rule of thumb when picking between using a ISL links for embedded switches vs putting the embedded switches into AG mode?
Complete and compatible Brocade environment. AG mode pro, less domains to manage, AG mode con, loss of some Brocade FOS functionality but what other considerations am I missing.
ISL vs AG mode is the wrong question
ISL vs framebasedtrunking is the correct question. i guess?!
or do you just want to know the difference between native and ag mode?
you already summarized the key pros/cons correctly. In most cases there are many blade centers with embedded switches involved and to keep administation simpler AG mode is prefered.
It also simplifies FOS upgrade considerations as the embedded switches support matrix can differ.
IMHO it all depends on the data center design and the forecast. We use embedded switches in our blade enclosures and have seen an explosive growth. The maximum domain id count per fabric supported by Brocade is 56. So you might not have a choice in the long run anyway.
We are running each fabric with around 100 switches in AG mode without problems. I would suggest to buy them with fabric vision and especially trunking license though.