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Prefix List ???

Hi,

I am a bit confused with the prefix list. Say I have "permit 10.16.0.0/14 le 21", what does it mean?

Thanks.

3 REPLIES

Re: Prefix List ???

(Just discovered netpro today ;)

"permit 10.16.0.0/14 le 21"

Ok, as I see it:

A mask lenght up to 24 bits in routes with the prefix of 10.16.0.0/14 will be accepted.

So this will aply to the 10.16.0.x range in this case

ge = value from = prefix length greater than or equal to the value. (ge is the lowest value of a range).

le = value up to = prefix length less than or equal to the value. (le is the highest value of a range)

eq = Exact value of the length.

So "permit 10.16.0.0/14 qe 19 le 21" will allow for routes with the prefixes from /19 up to /21

For more detail see:

see: http://www.cisco.com/en/US/products/ps5763/products_command_reference_chapter09186a00803e023f.html#wp1018810

Hope this helps

Johnmar

Re: Prefix List ???

Hi, andrew

The supernet 10.16.0.0/14 has an address range 10.16.0.0 ~ 10.19.255.255, so any routes within this range and has a mask less than or equal to 21 will be permited by this prefix list.

For example:

The supernet 10.16.0.0/15 has a prefix within this range and its mask is less than 21; it is permitted.

and so do 10.18.0.0/15,

and so do 10.16.0.0/16,

and so do 10.17.0.0/16,

...

and so do 10.19.248.0/21

The subnet 10.16.4.0/22 will not be permitted because its mask is too long.

The subnet 10.20.0.0/18 has a shorter mask, but it is out of range; it is denied.

Hope this help

SSLIN

Re: Prefix List ???

10.16.0.0/14 is a subnet, not supernet. sorry for the mistake.

SSLIN

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