From: Williams, Glenn (WILLIAMSG@xxxxxxxxxxxxx)
Date: Fri Mar 22 2002 - 16:06:23 GMT-3
All I was trying to do is pass 199.100.1.0/24, 199.100.2.0/24 etc....
The host 255.255.255.0 of the access list 100 I thought should lock in to
/24 only on the mask while the 0.0.255.255 should allow the 3rd octet to be
of any network.
So the full command is : access-list 100 permit ip 199.100.0.0 0.0.255.255
host 255.255.255.0
Unless I'm wrong which often I am, this list should permit 199.100.1.0/24,
199.100.2.0/24, 199.100.3.0/24 etc....
and so should p prefix-list 1 permit 199.100.0.0/16 ge 24 le 24
I typed and worded my question badly. A 192.100.0.0/24 network is not a
subnet, its a major network. Sorry.
GW
-----Original Message-----
From: Brian Lodwick [mailto:xpranax@hotmail.com]
Sent: Friday, March 22, 2002 1:02 PM
To: Williams, Glenn; ccielab@groupstudy.com
Subject: Re: Prefix lists
In access-list format this 199.100.0.0 0.0.255.255
equals this in prefix-list format
ip prefix-list 1 permit permit 199.100.0.0/16 le 32
Meaning you will allow all subnets from a /16 to a /32 if the first 2 octets
look like 199.100
I didn't quite catch exactly what you were saying on the other part.
"apply this to filter routes which will allow subnets 1 - 254 to pass of a
/24 network only."
Are you saying you don't want anything to pass that has less than a /24
mask?
If yes then your prefix list should look like this:
ip prefix-list 1 permit permit 199.100.0.0/16 le 24
Which would allow all updates from 199.100.0.0/16 to 199.100.0.0/24 but
nothing less than /24 will be allowed no /25 - /32
>>>Brian
>From: "Williams, Glenn" <WILLIAMSG@PANASONIC.COM>
>Reply-To: "Williams, Glenn" <WILLIAMSG@PANASONIC.COM>
>To: "'ccielab@groupstudy.com'" <ccielab@groupstudy.com>
>Subject: Prefix lists
>Date: Fri, 22 Mar 2002 12:51:25 -0500
>
>Friends,
>
>I know for BGP I can do this with an access list:
>
>access-list 100 permit ip 199.100.0.0 0.0.255.255 host 255.255.255.0
>
>apply this to filter routes which will allow subnets 1 - 254 to pass of a
>/24 network only. For a prefix-list would it look like this????:
>
>ip prefix-list 1 permit permit 199.100.0.0/16 ge 25 le 25
>
>is it the same or how would it look?
>
>GW
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