From: David Prall (dcp@dcptech.com)
Date: Fri Aug 15 2008 - 10:01:41 ART
Nope, can be used in just about every protocol I've tried. First time I saw
this was in the OSPF configuration guide.
router eigrp 1
redistribute static route-map default-only
ip access-list extended default-only
permit ip host 0.0.0.0 host 0.0.0.0
route-map default-only permit 10
match ip address default-only
David
-- http://dcp.dcptech.com> -----Original Message----- > From: Fahad Khan [mailto:fahad.khan@gmail.com] > Sent: Friday, August 15, 2008 3:38 AM > To: David Prall > Cc: Hobbs; Igor Manassypov; ccielab@groupstudy.com > Subject: Re: rule for prefix-access list conversion > > Plz confirm that this kind of ACL can only be used in BGP? > > Thanks, > > On 8/15/08, David Prall <dcp@dcptech.com> wrote: > > If this is for an access-list in a route-map for > redistribution you can use > an extended ACL. The first portion is the network and > the second portion is > the subnet mask. > > If my quick memory is right: > access-list 100 permit ip 192.168.0.0 0.0.255.64 > 255.255.0.0 0.0.255.64 > > David > > -- > http://dcp.dcptech.com > > > > -----Original Message----- > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On > > Behalf Of Hobbs > > Sent: Thursday, August 14, 2008 9:28 PM > > To: Igor Manassypov > > Cc: ccielab@groupstudy.com > > Subject: Re: rule for prefix-access list conversion > > > > Hi Igor, > > > > Well I don't think you can do it, but I could be > wrong. Some easy > > prefix-length only matches can be converted but not > complex ge or le > > matches. Here is my attempt and maybe someone can point out > > if I am path... > > > > Suppose you had the requirement: > > > > Only allow 192.168.0.0 routes with subnet less than /26 > > > > Our prefix-list would be easy: > > ip prefix-list ALLOW permit 192.168.0.0/16 le 26 > > > > Our ACL would be harder to find. but we know our first 16 > > bits: 192.168. > > > > So our acl looks like this for now: > > > > access-list 1 permit 192.168.x.x 0.0.x.x > > > > We dont care what the third bit is either so we could now go: > > > > access-list 1 permit 192.168.0.x 0.0.255.x > > > > That leaves the last bits of the network and mask. We can > > break out the > > networks of the 4th octet in binary: > > > > xxxx xxxx > > > > /24 = 0000 0000 > > > > /25 = 0000 0000 > > 1000 0000 > > > > /26 = 0000 0000 > > 0100 0000 > > 1000 0000 > > 1100 0000 > > > > /27 = 0000 0000 > > 0010 0000 > > 0100 0000 > > 0110 0000 > > 1000 0000 > > 1010 0000 > > 1100 0000 > > 1110 0000 > > > > We can already see where this is headed. Our first two bits > > are "don't care" > > and our last 6 must be 0 in order to be considered > less than /26. > > > > so we could have this: > > > > access-list 1 permit 192.168.0.0 0.0.255.128 > > > > However this would prevent a problem for networks such as > > 192.168.11.0/28because the network has all 0's and > for all the router > > knows could be a /24, > > /25 or /26 with all 0's. > > > > So we need to deny all of these: > > > > 192.168.0.0/27,/28,/29,/30 > > 192.168.1.0/27,/28,/29,/30 > > 192.168.2.0/27,/28,/29,/30 > > > > Don't know a way of doing it without too many entries...and > > if we were to > > deny these first we would deny their /24,/25,/26 > counterparts... > > > > maybe that's why prefix-lists were invented... > > > > > > > > > > > > On Thu, Aug 14, 2008 at 8:38 AM, Igor Manassypov > > <imanassypov@rogers.com>wrote: > > > > > Hello, > > > > > > What is the rule for converting between 'prefix-list' and > > 'access-list'? > > > > > > Thanks! > > > > > > > > > Igor M., M.Eng, P.Eng > > > Network Architect > > > > > > > > > Blogs and organic groups at http://www.ccie.net > > > > > > > > ______________________________________________________________ > > _________ > > > Subscription information may be found at: > > > http://www.groupstudy.com/list/CCIELab.html > > > > > > Blogs and organic groups at http://www.ccie.net > > > > ______________________________________________________________ > > _________ > > Subscription information may be found at: > > http://www.groupstudy.com/list/CCIELab.html > > > Blogs and organic groups at http://www.ccie.net > > > ______________________________________________________________ > _________ > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html > > > > > > > > > > > > > -- > FAHAD KHAN > > BE Computer Systems NED, > > CCNA,CCDA,CCNP,FOUNDFE,CLSE,QOS,JNCIA,JNCIS,MCP,CCIE (Written) > > Systems Support Engineer, Premier Systems (Pvt) limited, > > Karachi, Pakistan > > 92-321-2370510.
Blogs and organic groups at http://www.ccie.net
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