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Re: Community List Verification posted 09/08/2001
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Perhaps I have my scenario set up differently than yours, but it looked to
me that Figure 3-26 on page 270 indicated that 10.2.1.0/24, 10.2.2.0/24, and
10.2.3.0/24 were all in AS2000, which I defined as loopback interfaces on
the Austria router.  If I set the community for all routes going to Idaho as
2000:100, then added 100:2000 to the same routes on Idaho, I then see all
three routes with the same communities on Colorado, which are 100:2000 and
2000:100.  If p2r5 is Colorado, all three routes should look the same, and
the access list should match all three exactly.  The way to distinguish
these three routes with exact-match is to have routes that have both
100:2000 and 2000:100 but also have other communities in addition to those
two communities.  Given the scenario on page 270, I think the example at the
bottom of page 282 would look the same with or without the exact-match
parameter.

----- Original Message -----
From: "Michael Wong" <Michael.Wong@xxxxxxxxxx>
To: "Groupstudy - CCIELAB (E-mail)" <ccielab@xxxxxxxxxxxxxx>
Sent: Thursday, September 06, 2001 9:59 PM
Subject: Community List Verification


> Hi Group
>
> I would just like some verification on how community-lists operate when
matching multiple community values. This in reference to Doyle Vol II p.282
>
> Here is a community list matching 2 community values which I am using.
>
>    -  ip community-list 1 permit 100:2000 2000:100
>
> I have 3 routes on that router. One route has 100:2000 2000:100 and the
other 2 routes have only 2000:100 as you can see below.
>
> p2r5#sh ip bgp 10.2.1.0
> BGP routing table entry for 10.2.1.0/24, version 3
> Paths: (1 available, best #1, table Default-IP-Routing-Table)
>   Advertised to peer-groups:
>      CLIENTS
>   2000
>     10.1.255.8 from 10.1.255.8 (10.1.255.8)
>       Origin IGP, metric 0, localpref 100, valid, internal, best
>       Community: 2000:100
>
> p2r5#sh ip bgp 10.2.2.0
> BGP routing table entry for 10.2.2.0/24, version 2
> Paths: (1 available, best #1, table Default-IP-Routing-Table)
>   Advertised to peer-groups:
>      CLIENTS
>   2000
>     10.1.255.8 from 10.1.255.8 (10.1.255.8)
>       Origin IGP, metric 0, localpref 100, valid, internal, best
>       Community: 100:2000 2000:100
>
> p2r5#sh ip bgp 10.2.3.0
> BGP routing table entry for 10.2.3.0/24, version 4
> Paths: (1 available, best #1, table Default-IP-Routing-Table)
>   Advertised to peer-groups:
>      CLIENTS
>   2000
>     10.1.255.8 from 10.1.255.8 (10.1.255.8)
>       Origin IGP, metric 0, localpref 100, valid, internal, best
>       Community: 2000:100
>
>
> The book states that when using the community-list to match multiple
values, the community-list (as shown above) will match either or both. If
you want to match both, you have to use exact-match. However, this where I
get stuck ...... look at the following outputs below .....
>
> p2r5#sh ip bgp community-list 1
> BGP table version is 14, local router ID is 10.1.255.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
>    Network          Next Hop            Metric LocPrf Weight Path
> *>i10.2.2.0/24      10.1.255.8               0    100      0 2000 i
>
> p2r5#sh ip bgp community-list 1 exact-match
> BGP table version is 14, local router ID is 10.1.255.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
>    Network          Next Hop            Metric LocPrf Weight Path
> *>i10.2.2.0/24      10.1.255.8               0    100      0 2000 i
>
> As you can see, whether I use the "exact-match" command or not, it still
matches on both values .... not according to the book.
>
> Has anyone else experienced this ????
>
> Thanks ..... MW
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