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Odd and Even Routes - Further Observation!!! [7:61699] posted 01/23/2003
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Hello,Based on my problem of understanding odd and even routes, I finally
took the 'bull by it's horns' and made some observations this morning.These
are my notes as I work towards the CCIE Lab so hopefully it helps
candidates like me out there.Any further observation/comments welcome:This
is based on a Class A network:  0.0.0.0 = Even1.0.0.0 = OddMask
portion:254.0.0.0
= match exact254.255.255.255 = match anyEx. 1st Octet10.0.0.0/8
11.0.0.0/8
12.0.0.0/8
13.0.0.0/8i.) To match exactly ONLY 10.0.0.0/8 even routes in the 1st
octet:#access-list 10 permit 10.0.0.0 254.0.0.0ex.
   Network          Next Hop            Metric LocPrf Weight Path
*> 10.0.0.0         144.228.148.6         9999             0 26844 i
*> 12.0.0.0         144.228.148.6         9999             0 26844 i
*> 144.228.148.4/30 0.0.0.0                  0         32768 iNote: the
all 0's in the
mask-------------------------------------------------------------------------------ii.)
To match 10.0.0.0/8 AND ANY other even routes in the 1st octet:
     ex. 172.16.0.0/16, 192.168.10.0/24#access-list 10 permit 0.0.0.0
254.255.255.255NOTE: the 255's in the mask.ex.
 Network          Next Hop            Metric LocPrf Weight Path
*> 10.0.0.0         144.228.148.6                          0 26844 i
*> 12.0.0.0         144.228.148.6                          0 26844 i
*  144.228.148.4/30 144.228.148.6            0             0 26844 i
*>                  0.0.0.0                  0         32768 i
*> 192.149.105.0    144.228.148.6            0             0 26844
i---------------------------------------------------------------------------------iii.)
To match odd routes ONLY in 10.0.0./8 in the 1st octet:#access-list
1.0.0.0 254.0.0.0ex.
   Network          Next Hop            Metric LocPrf Weight Path
*> 11.0.0.0         144.228.148.6         9999             0 26844 i
*> 13.0.0.0         144.228.148.6         9999             0 26844 i
*> 144.228.148.4/30 0.0.0.0                  0         32768
i--------------------------------------------------------------------------------iv.)
To match odd routes in 10.0.0.0/8 AND ANY other odd routes in the 1st
octet:#access-list 1.0.0.0 254.255.255.255ex.
  Network          Next Hop            Metric LocPrf Weight Path
*> 7.7.7.0/24       144.228.148.6         9999             0 26844 i
*> 11.0.0.0         144.228.148.6         9999             0 26844 i
*> 13.0.0.0         144.228.148.6         9999             0 26844 i
*> 144.228.148.4/30 0.0.0.0                  0         32768 i
*> 207.96.46.0      144.228.148.6         9999             0 26844 i
*> 209.96.46.0      144.228.148.6         9999             0 26844 i
------------------------------------------------------------------------------   

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