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From: Scott Townsend on 24 Apr 2006 14:00
We received a Router from an ISP and they have the Following Line in it.

ip route A.B.C.0 255.255.255.0 Null0 254 permanent

Where the local Ethernet Interface is: A.B.C.1 255.255.255.0

What is the Purpose of this? If the Ethernet interface is Down, route all
traffic to NULL?

Thanks,
Scott<-


From: Merv on 24 Apr 2006 14:08
correct

From: java321 on 24 Apr 2006 21:42
The purpose is to prevent routing loops.

Here is an example
http://www.cisco.com/en/US/tech/tk364/technologies_tech_note09186a00801c9a6e.shtml.

Good Luck

"Scott Townsend" <scott-i@.-N0-SPAMplease.enm.com> wrote in message
news:on83g.19574$tN3.10995(a)newssvr27.news.prodigy.net...
> We received a Router from an ISP and they have the Following Line in it.
>
> ip route A.B.C.0 255.255.255.0 Null0 254 permanent
>
> Where the local Ethernet Interface is: A.B.C.1 255.255.255.0
>
> What is the Purpose of this? If the Ethernet interface is Down, route all
> traffic to NULL?
>
> Thanks,
> Scott<-
>


From: Mooron on 25 Apr 2006 15:04

Scott Townsend wrote:
> We received a Router from an ISP and they have the Following Line in it.
>
> ip route A.B.C.0 255.255.255.0 Null0 254 permanent
>
> Where the local Ethernet Interface is: A.B.C.1 255.255.255.0
>
> What is the Purpose of this? If the Ethernet interface is Down, route all
> traffic to NULL?
>
> Thanks,
> Scott<-


Also note the high metric of 254 which makes it the
route of "last resort." A directly connected network
has a metric of 0. Under normal cirucmastances,
when the Ethernet is up, the route does nothing.

It prevents bouncing of packets between you and
your ISP when the Ethernet interface is down.

- Mooron

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