Re: WCCP talk..

[lincoln dale <ltd () interlink com au>]

At 11:16 PM 11/10/98 -0500, alex () nac net wrote:
> > i don't think i am --
> > i would assume that the cache design would perform suitable sanity checks
> > prior to sending out a heartbeat.  if the design is sound, the cache would
> > not be capable of sending out WCCP packets if it has 'died' in some way.
>
> You can't be serious.
>
> A cache may check itself, but my arguement is that this self-checking
> scheme may fail, seeing itself as alive, but not able to actually serve
> requests.

lets go through the following scenario.  i've no idea if a CCE works this
way, but lets say for arguments sake that it does:
 - internally, a process goes and stores an object in the cache under URL
A.  the contents of the object is some unique number.
 - the process then goes and requests, via HTTP, (say over the loopback
interface) that object.
just about all of the functionality of the cache is then tested:
 - the disk store works,
 - the cache is able to accept a HTTP request,
 - the tcp stack is working
 - the internal processes of associating a cache object to a request works
(and the disk worked ...).
everything has therefore been checked, except external network
connectivity.  the sending of the WCCP packet and subsequent receival by
the router tests that as working.

i guess what we come down to is this: is it the router's responsibility to
maintain state on devices around it, or of devices to inform the router of
their state.  imho, its a moot point, but i dare say that it was probably
easier for cisco to implement the former, as it would have involved far
less lines coded in IOS than the latter solution.

cheers,

lincoln.