From: P729 (p729@cox.net)
Date: Thu Dec 19 2002 - 00:47:34 GMT-3
"I am curious if the mechanism is interal or external to the routing
protocol process?"
It occurs to me that since this command is issued under a specific routing
process that the mechanism is internal to the routing process.
In any event, the net result is disabling the transmission of protocol
packets on the specified interface(s). Your knowledge of the specific
protocol behavior would lead you to deduce the net effect. For example,
distance-vector protocols will still listen for and install routes from
updates learned through a passive interface, while link-state protocols will
fail to form adjacencies because of Hello suppression so routes cannot be
learned through passive interfaces.
Regards,
Mas Kato
https://ecardfile.com/id/mkato
----- Original Message -----
From: "tan" <tan@dia.janis.or.jp>
To: "Ccielab (E-mail)" <ccielab@groupstudy.com>
Sent: Wednesday, December 18, 2002 6:20 PM
Subject: internals of passive interface
passive interface blocks rip broadcasts 255.255.255.255. What exactly is the
mechanism here? Because the command is not routing protocol specific, I am
curious if the mechanism is interal or external to the routing protocol
process?
example
-rip first actually generates the broadcast update to 255.255.255.255 but
some other process kills it because the passive command (in the sense
external to rip process) says to kill broadcasts to 255.255.255.255
-same thing as above, but other process kills it because there is a rip
identity marker in the header
-rip internally does not generate broadcast at all
-other
The inadequacy I find with book descriptions is the focus on the result of
passive int on a case by case routing protocol basis. Rather than say
passive results in this or that, can we say definitively is does one thing
since it is not a protocol specific command. Note, this command does not
apply to BGP, and since BGP is unique from the others in that it is an upper
layer protocol, can we say passive command works at layer 3 and 4 the same
across all routing protocols but external to them? As in..."passive
interface kills packets to all_hosts_broadcsts/subnet_broadcasts, WHEN in
combination a routing protocol is identified in the header?" I find this
easier to deal with than memorizing case by case situations. Or, do we just
got to know the idiosyncrasies on a case by case routing protocol basis?
.
.
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