From: alain faure (alainfaure@xxxxxxxx)
Date: Sun Jan 13 2002 - 08:51:42 GMT-3
Hello,
Yes you are right, but is there another solution ?
Because my problem is ...yes, i know it is a bad design, but real case
situation :-)
The summary route to null0 may black hole all the packets going out of canada 1
to a network outside the eigrp AS but not known in the canada 1's routing
table(For example 182.16.5.0 / 24) and if there is a default route in canada 1.
> canada 1 (s0)--------------30.0.0.0----------------- mexico 1
> 182.16.3.0 / 24
> 182.16.4.0 / 24
canada 1's routing table mexico 1's routing table
0.0.0.0 s0 mexico 1 182.16.5.0/24 ethernet 0
182.16.0.0 / 16 null0 182.16.0.0/16 canada 1
182.16.3.0 / 24 tok 0
182.16.4.0 / 24 tok 1
---(dest:182.16.5.1)----------------------------------->
The packet comming into canada 1 will be black hole by the null0 route.
If no null0 route, it is ok, it will be forward to mexico 1
Best regards
--- Markus Haas <mh@nmc-m.dtag.de> a icrit : > Normaly the NULL0 route is to
prevent routing loop (see Dolye V.1 P. 380/381)
>
> I think that you cannot avoid the NULL0 route, because it is an default
> behavior.
>
>
> HTH,
> Markus
>
> -----Urspr|ngliche Nachricht-----
> Von: nobody@groupstudy.com [mailto:nobody@groupstudy.com]Im Auftrag von
> alain faure
> Gesendet: Samstag, 12. Januar 2002 18:47
> An: ccielab@groupstudy.com
> Betreff: avoid null0 with eigrp manual summarization
>
>
> Hello,
>
> i just bought the ccie pratical studies and try a example page 706 (with some
> little changes).
>
> when i do manual summarization on the serial interface of canada 1 i got the
> summary with NULL0 on canada 1 and the summary on mexico witch is correct.
>
> canada 1 (s0)--------------30.0.0.0----------------- mexico 1
> 182.16.3.0 / 24
> 182.16.4.0 / 24
>
> int s0
> ip add 30.0.0.1 255.0.0.0
> ip summ eigrp 12 182.16.0.0 255.255.0.0
>
> router eigrp 12
> net 182.16.0.0
> net 30.0.0.0
> no auto
>
> On page 705 they say auto-summary is bad because it generate a route to NULL0
> so
> How to avoid route to NULL0 on canada 1 with manual summary ?
>
> Thank you very much
>
> note : For canada 1 i use : IOS (tm) 2500 Software (C2500-JK8OS-L), Version
> 12.2(1b)
>
> best regards
>
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