From: Popgeorgiev Nikolay (nikolay.popgeorgiev@siemens.com)
Date: Wed Mar 08 2006 - 06:01:39 GMT-3
Mushtaq,
It will match not only 10.10.0.0 and 10.10.0.4
But also
10.10.x.y/30
Where x can be from 0-255
And y can be a each umber which can be devided by 4 - ( 0,4,8,12 ..., 252)
Hope this makes it more clear
Best,
Nick
-----Original Message-----
From: Mushtaq A. Khan [mailto:mak.ccie2b@gmail.com]
Sent: Wednesday, March 08, 2006 7:06 AM
To: Troy Levin
Cc: ccielab@groupstudy.com
Subject: Re: IP Prefix-List issue
Troy,
Great. Thanks for your kind efforts to test this as well. Now I wrote in my
NVRAM :)
Mushtaq
On 3/7/06, Troy Levin <troylevin@hotmail.com> wrote:
>
> Hi Mushtaq,
>
> My test results show that a prefix list of "ip prefix-list permit
> 10.10.0.0/16 ge 30 le 30" will match ONLY on /30 subnets where the first
> 16
> bits are 10.10
>
> /16 means match the first 16 bits left to right without skipping must
> match.
> ge 30 le 30 means that the subnet must be equal to /30 or 255.255.255.252.
>
> R1#sh run | b router bgp
> router bgp 1
> no synchronization
> bgp log-neighbor-changes
> neighbor 131.108.50.2 remote-as 2
> neighbor 131.108.50.2 prefix-list Filter in
> no auto-summary
> !
> ip classless
> no ip http server
> !
> !
> !
> ip prefix-list Filter seq 5 permit 10.10.0.0/16 ge 30 le 30
>
> R2#sh run | B router bgp
> router bgp 2
> no synchronization
> bgp log-neighbor-changes
> network 10.10.0.0 mask 255.255.255.252
> network 10.10.0.4 mask 255.255.255.252
> network 10.10.13.0 mask 255.255.255.252 -----> also makes it through
> filter
> on R1
> network 12.12.0.0 mask 255.255.255.252 -----> /24 does not make it
> through filter on R1
> neighbor 131.108.50.1 remote-as 1
> no auto-summary
>
> R1#sh ip bgp
> BGP table version is 10, local router ID is 1.1.1.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 10.10.0.0/30 131.108.50.2 0 0 2 i
> *> 10.10.0.4/30 131.108.50.2 0 0 2 i
> *> 10.10.13.0/30 131.108.50.2 0 0 2 i
>
> HTH,
>
> Troy
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Mushtaq A. Khan
> Sent: Tuesday, March 07, 2006 3:00 PM
> To: ccielab@groupstudy.com
> Subject: IP Prefix-List issue
>
> All,
>
> I have recently read one very good posting on prefix-list in the
> groupstudy
> and thought I now understand it very well but look like I still have some
> confusions. Can someone help me out here.
>
> For the prefix list "ip prefix-list permit 10.10.0.0/16 ge 30 le 30" I
> think
> it will match the first 16 bits and will use a mask of 255.255.255.252. If
> this is correct, will this permit 10.10.0.0 and 10.10.0.4 or only
> 10.10.0.4as the mask seems to limit to match the 30th bit.
>
> Thanks,
> Mushtaq
>
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