On Thu, 2007-07-26 at 17:36 +1000, David Kempe wrote: > Oh and at Glen Turner - how is bandwidth greater than 155Mbps considered > low? :) (yes i know you work at aarnet! :)
Hi Dave, It depends on your situation, obviously. Here's a quick summary from the ISP's view. It doesn't make economic sense to light metro fibre using anything less than gigabit ethernet (fast ethernet will actually cost you more). Offshore bandwidth comes in chunks. 155Mbps is the smallest, 622Mbps is the next size up. So for an ISP wanting to get the utmost out of the expensive Southern Cross Cable Network between Sydney and California/Oregon bandwidth optimisation only works on the lowest pipe size. >From the customer's point of view if you are taking a virtual service, like a rate-limited tunnel, or if you have some non-fiber service in the last mile then bandwidth optimisation devices make sense for the customer to deploy. That assumes you can get access to both ends of the link, such as for an inter-office virtual link. There are two other scenarios where similar boxes make some sense. Firstly, a lot of customers have mistuned TCP hosts, and terminating those connections much closer improves performance. Secondly, if you run a QoS network connected to a non-QoS network then you might want to do deep packet inspection and set the DSCP on incoming traffic. Otherwise you end up with a situation where the user on the non-QoS network gets a nice picture but the user on the QoS network gets the poor picture. But you have to trade this off against the evil of having a middlebox. Very few of these boxes have robustness, hardware or features suitable for critical traffic. Best wishes, Glen -- Glen Turner -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
