From: yu chunyan (yuchunyan@hotmail.com)
Date: Fri Sep 12 2003 - 11:56:11 GMT-3
Hi,
If you are not confident on regexp, how about this way:
route-map ex1 permit 20
match as-path 12
match as-path 13
set local-preference 400
ip as-path access-list 12 permit ^698_
ip as-path access-list 13 permit _405_
These two "match" have "and" relation in route-map, which has the same
effect as one complex expression.
Bin.
>From: raj_tpd@comcast.net
>Reply-To: raj_tpd@comcast.net
>To: "Gary Bartlett" <ciscokid@sympatico.ca>
>CC: <ccielab@groupstudy.com>
>Subject: Re: prefix & AS-path questions
>Date: Fri, 12 Sep 2003 04:33:53 +0000
>
>Here is what I think.
>
>For
>1. sets the local pref to 400 for any paths learned directly from AS 698
>that
>pass through AS 405.
>
>Answer i think: ip as-path access-list 12 permit ^698_(.+_)*405_
>
>when you said ^698_(.+_)*405_(.+_)$ means received from AS698 pass through
>any
>number of AS then match 0 or more sequence of AS405 and then match again
>any
>number of AS till origin.
>
>Why do it that way when there is a build in function.
>
>^698_(.+_)*405_
>Where it says received from AS698, match any number of AS in between then
>match
>AS405 and then I don't care what else it passes through till origin. I only
>care about received AS and pass through AS405. Leave the rest on the
>program to
>figure it out.
>
>For
>2. Sets the weight to 10,000 and the local preference to 60 for networks in
>the
>range 172.16.0.0/16 to 172.31.0.0/16 network, and any of their subnets.
>
>Answer i think: ip prefix-list test22 seq 5 permit 172.16.0.0/12 ge 16 le
>32
>
>This is saying match first 12 bits exactly what I have said and then from
>bit
>16 to 32 I do not care.
>
>
>I think the rest looks good.
>
>I might be totally off, I that case please do correct me. I will learn a
>thing
>or two. Just my 2 cents.
>
>Raj
> > So it's coming down to the wire for me now, I'll be taking the exam on
> > Sept 18th in RTP. There are still a few things I'm not comfortable with,
> > so if you could help me with these I'd appreciate it.
> > Thanks,
> > Gary
> >
> > 1. Construct a route map that sets the BGP local preference to 200 for
> > any paths learned directly from AS 307, sets the local pref to 400 for
> > any paths learned directly from AS 698 that pass through AS 405, and
> > denies all other paths.
> > 2. Construct a route map that:
> > - Sets the origin code to "incomplete" and the local preference to 50
> > for the 10.0.0.0/8 network and any of its subnets.
> > - Sets the weight to 10,000 and the local preference to 60 for networks
> > in the range 172.16.0.0/16 to 172.31.0.0/16 network, and any of their
> > subnets.
> > - Sets the local preference to 70 for any 192.168.x.0/24 network or
> > subnet.
> > - Denies all other prefixes.
> >
> > MY ANSWERS
> > 1)
> > route-map ex1 permit 10
> > match as-path 11
> > set local-preference 200
> > route-map ex1 permit 20
> > match as-path 12
> > set local-preference 400
> > ip as-path access-list 11 permit ^307_
> > ip as-path access-list 12 permit ^698_(.+_)*405_(.+_)$
> > -------------------------
> >
> > 2)
> > route-map ex2 permit 10
> > match ip address prefix test21
> > set origine incomplete
> > set local-preference 50
> > route-map ex2 permit 20
> > match ip address prefix test22
> > set weight 10000
> > set local-preference 60
> > route-map ex2 permit 30
> > match ip address prefix test23
> > set local-preference 70
> > ip prefix-list test21 seq 5 permit 10.0.0.0/8 le 32
> > ip prefix-list test22 seq 5 permit 172.16.0.0/12 ge 16 le 32
> > ----------------------
> > ip prefix-list test23 seq 5 permit 192.168.0.0/16 le 32
> >
> > COMMENTS:
> > 1) My problem is that they said passed through as 405, but they didn't
> > say originated from AS 405, that's why my answer is different...
> > 2) I added ge 16 because in the question they said that the 3rd octet
> > could be any # in the range of 16 to 31, but the subnet would still be
> > /16 to /32...
> > THERE ANSWERS
> > 1.
> > route-map test1 permit 10
> > match as-path 1
> > set local preference 200
> > route-map test1 permit 20
> > match as-path 11
> > set local preference 400
> >
> > ip as-path access-list 1 permit ^307_
> > ip as-path access-list 11 permit ^698_(.+_)*405_ -----------------
> > 2.
> > route-map test2 permit 10
> > match ip address prefix test2a
> > set origin incomplete
> > set local-preference 50
> > route-map test2 permit 20
> > match ip address prefix test2b
> > set weight 10000
> > set local-preference 60
> > route-map test2 permit 30
> > match ip address prefix test2c
> > set local-preference 70
> > ip prefix-list test2a seq 5 permit 10.0.0.0/8 le 32
> > ip prefix-list test2b seq 5 permit 172.16.0.0/12 le 32
> > ----------------
> > ip prefix-list test2c seq 5 permit 192.168.0.0/16 le 32
> >
> >
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