Sorry for the repetitive post but your math is 100% correct if the question is
Write a single access-list that matches all odd loopback subnets on R1 However if the question asked Write an access list that only matches the odd loopback subnets on R1 in as few lines as possible i think the answer would be access-list 1 permit 10.10.101.0 0.0.2.0 access-list 1 permit 10.10.105.0 0.0.0.0 On Thu, Aug 12, 2010 at 7:13 PM, Aaron Moreck <[email protected]> wrote: > I would also have to say that my solution takes into account all addresses > that you put on the example but i now realize that you may have been looking > for the acl statement that matches ONLY the odd loopbacks on R1 with the > assumtion that there might be other networks advertised beyond what is shown > in the question > > So i would have to change my answer to > > access-list 1 permit 10.10.101.0 0.0.2.0 > access-list 1 permit 10.10.105.0 0.0.0.0 > > the trick being the 3rd octet > You would actually need to lines in the access list > > 101= 0110 0101 > 103= 0110 0111 > mask 0000 0010 = 2 > > 105=0110 1001 > > Argubably you could use > > access-list 1 permit 10.10.101.0 0.0.2.255 > access-list 1 permit 10.10.105.0 0.0.0.255 > > > > > On Thu, Aug 12, 2010 at 6:53 PM, Aaron Moreck <[email protected]> wrote: > >> The way i would approach this is to see what is in common. >> >> GETTING TO THE SOLUTION >> -First octet of the loopbacks on R1 all start with 10 >> -who cares about the 2nd Octet >> -3rd Octet should be odd >> -4th octet needs to be zero >> >> SOLUTION: >> access-list 1 permit 10.0.1.0 0.255.254.0 >> >> EXPLANATION >> >> >> 1st Octet: 0 wildcard will force octet to match exactly (10) >> 2nd Octet: all binary 1's in wild card meaning that they could be >> anything 0-255 are acceptable decimal values >> 3rd Octet: >> >> Given Octet: 0000 0001 (1) >> Wild Card Mask 1111 1110 (254) >> >> All 1 bits are don't cares where 0 bits have to match. This says that >> first bit of this octet must be 1 which is true for all odd numbers >> >> 4th Octet: 0 wildcard will force octet to match eactly (0) >> >> >> Aaron >> >> >> >> >> >> >> On Wed, Aug 11, 2010 at 10:50 AM, Aryan <[email protected]>wrote: >> >>> Can Someone please share how to calculate complex wild card for ACLs >>> from binary prospective. >>> >>> I tried doing AND and XOR method but somehow didn't get it rightly. >>> >>> here is quick requirement those I tested. >>> >>> R1 - >>> >>> R1#sh prot | e un|do >>> Global values: >>> Internet Protocol routing is enabled >>> FastEthernet0/0 is up, line protocol is up >>> Internet address is 11.11.11.1/24 >>> Serial0/0 is up, line protocol is up >>> Internet address is 12.12.12.1/24 >>> Loopback0 is up, line protocol is up >>> Internet address is 10.10.100.1/24 >>> Loopback1 is up, line protocol is up >>> Internet address is 10.10.101.1/24 >>> Loopback2 is up, line protocol is up >>> Internet address is 10.10.102.1/24 >>> Loopback3 is up, line protocol is up >>> Internet address is 10.10.103.1/24 >>> Loopback4 is up, line protocol is up >>> Internet address is 10.10.104.1/24 >>> Loopback5 is up, line protocol is up >>> Internet address is 10.10.105.1/24 >>> Loopback6 is up, line protocol is up >>> Internet address is 10.10.106.1/24 >>> >>> >>> >>> R2 - >>> >>> R2#sh prot | e un|do >>> Global values: >>> Internet Protocol routing is enabled >>> Serial0/0 is up, line protocol is up >>> Internet address is 12.12.12.2/24 >>> Loopback0 is up, line protocol is up >>> Internet address is 22.22.22.22/24 >>> >>> >>> Challenge - Filter all ODD subnets of R1 (loopback ranges) to reach R2's >>> Loopback >>> >>> >>> How I tried to solve it is >>> >>> First convert ODD blocks into binary: >>> >>> >>> 10.10.101.0/24 >>> 10.10.103.0/24 >>> 10.10.105.0/24 >>> >>> = >>> >>> 00001010 00001010 01100101 00000000 >>> 00001010 00001010 01100111 00000000 >>> 00001010 00001010 01101001 00000000 >>> >>> >>> next step - performed AND operation >>> >>> AND: >>> >>> 00001010 00001010 01100101 00000000 >>> 00001010 00001010 01100111 00000000 >>> 00001010 00001010 01101001 00000000 >>> ------------------------------------------------------------- >>> 00001010 00001010 01100001 00000000 >>> ------------------------------------------------------------- >>> >>> back in binary - 10.10.97.0 >>> >>> Next step - Performed XOR operation >>> >>> XOR: >>> >>> 00001010 00001010 01100101 00000000 >>> 00001010 00001010 01100111 00000000 >>> 00001010 00001010 01101001 00000000 >>> --------------------------------------------------------------- >>> 00000000 00000000 00001110 00000000 >>> ---------------------------------------------------------------- >>> >>> >>> back in binary - 0.0.14.0 >>> >>> >>> final net id and wildcard pair comes as - 10.10.97.0 0.0.14.0 >>> >>> but obviously I am making some mistake some where. >>> >>> >>> Document I referred: - http://www.ine.com/resources/01700370.htm >>> >>> >>> kindly help and suggest the right way with few examples >>> >>> Thanks! >>> Aryan >>> >>> >>> >>> >>> _______________________________________________ >>> For more information regarding industry leading CCIE Lab training, please >>> visit www.ipexpert.com >>> >>> >> >
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
