Re: IGPs in use

[Tony Li <tli () juniper net>]

xxvaf () WR BBNPLANET COM (Vince Fuller) writes:

>     There are some drawbacks to IS-IS: ...
>
> IS-IS uses an underlying traffic exchange which is based on OSI/CLNS. This
> introduces requirements for OSI addressing and CLNS implementation which are
> otherwise useless in an IP-centric network. IMHO, this represents a
> substantial bit of operational complexity (obtaining CLNS addresses, teaching
> operations/engineering staff how to use them and interpret them while
> debugging, etc., etc...)


While it does require OSI addressing, it does not require CLNP forwarding.
As to the engineering and operations aspects, the additional complexity
can, with a reasonable implementation, be almost completely hidden.  For
example:

> show isis adjacency
IS-IS adjacency database:
Interface    System         L State        Hold (secs) SNPA
fxp0.0       lab5           2 Up                    16 0:0:c0:cc:a0:bf
fxp0.0       lab2           2 Up                    25 0:0:c0:e8:69:db
fxp0.0       lab10          1 Up                    22 0:a0:c9:36:b3:a6


> On a pragmatic note, though, the relative successes of IS-IS and OSPF in the
> large provider marketplace probably has more to do with the relative competence
> of the cisco's original OSPF and IS-IS implementors than anything else
> (only someone else who suffered through OSPF's growing pains way back in
> the 9.0-9.1 days can really appreciate this comment...)


Very true, tho those of us who had ringside seats do sympathize.  ;-)

Tony