Re: LISP for web

"Marco Baringer" <mb@xxxxxxx> writes:

[Snippedy-Snip]
>>
>> Need more input? Ask!
>
> i'm asking :)
>

So you dare you ask, hm ? ;-) Here you go:

Any large scale web app that is business critical is based on a few
fundamental components.

1. All components are redundant
-> So you need at least two routers, two switches, two machines ...
And also two UPS boxes, two power supplies in each devices...

2. Load balancing is done based on content and on network traffic
Cisco and Baynetworks are examples for producers of stuff like
LoadBalancer that direct traffic based on content and network
bandwidth requirements to parts of the network infrastructure and
to the application servers

3. High availability is achieved on application level either by
having mulptiple instances of a given app on several machines
(which of course are running in buildings that are at least
2 km apart - according to NATO regulations) and/or by
putting the apps in packages that are switchable between
machines in case of a hardware failure. Commercial solutions
are IBM'S HACMP or HP's MC/ServiceGuard. These solutions facilitate
the switching based on monitoring critical resources and also
by updating each node in a cluster about health status of each
node. If a node experiences problems all other nodes are either
notified actively or passively (when that node is no more
reachable). Then the packages (a DB, a CL image proces, the Web
server, whatever) gets shutdown on the problem node and started
on another, pre-defined failover sequence node. In doing so the
IP address of that app (NOT of the interface, in a HA cluster
each application is assigned an IP address) is taken onto the
new node's network interface. The network infrastructure is
notified about the new MAC address to IP address mapping using
the ARP protocol and other mechanisms. Therefore the load
balancer, the switch and all other devices "know" that the
app is now running on a new node. Or, more precisely, they
don't care because the switches next to the nodes take
care of this using IP protocol facilities.


Even Amazon and Ebay are running based on the architecture outlined
above.

Hey, normally I do charge 1250 EUR for this type of consulting ;-)

Want more? Ask!

Frank

.

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