All things related to multicast

[ken lindahl <>]

hi Toerless et al,

Toerless Eckert wrote:   
>  c) In general we recommend not to enable SAP, so i am very interested
>     to get a reinforcement about how useful this command still is
>     to common user practices ;-))

i will shamelessly confess that SAP listening is enabled in all
of our routers, and on more than one occasion i have successfully
used "show ip sap" to quickly narrow down the location of a problem.
("ok, 134 sessions shown on this router, 132 on this one, but only 67
on this one, wtf???")

> After all: 
>     There is really nothing in SAP that you could not do better by 
>     running SAP on a host system (PC, unix, linux,...).

we have nearly 100 routers in nearly as many buildings on campus and
in remote offices. i hope you're not suggesting that we install and
operate a host system in each of those locations. imo, we're much
better off being able to use tools on the routers themselves.

>     The router is just receiving these messages and you can display
>     them with "show" commands. Nothing else. The forwarding of SAP,
>     as already said by someone else on this thread is completely
>     unaffected.

understand that. the "show" commands are exactly what i've used in
the past.

>     The problem obviously is that because SAP on texithe router is used
>     ONLY for such random "show" commands by few users, there is
>     no real business incentive to follow all the newest developments
>     into decoding new type of SAP messages, so the command also
>     becomes less and less useful - and it was only of limited use
>     in the beginning.

if there's still business incentive for promoting multicast, then
there ought to be business incentive for making it as easy as pos-
sible to debug, and the question becomes how many users think SAP
listening makes it easier to debug multicast problems. i do, but
i don't know how many others feel the same.

thanks,
ken