Level 3 BGP Advertisements

Matt Addison matt.addison at lists.evilgeni.us
Wed Aug 29 18:08:13 CDT 2012


Sent from my mobile device, so please excuse any horrible misspellings.

On Aug 29, 2012, at 18:30, james machado <hvgeekwtrvl at gmail.com> wrote:

> On Wed, Aug 29, 2012 at 1:55 PM, STARNES, CURTIS
> <Curtis.Starnes at granburyisd.org> wrote:
>> Sorry for the top post...
>>
>> Not necessarily a Level 3 problem but;
>>
>> We are announcing our /19 network as one block via BGP through AT&T, not broken up into smaller announcements.
>> Earlier in the year I started receiving complaints that some of our client systems were having problems connecting to different web sites.
>> After much troubleshooting I noticed that in every instance the xlate in our Cisco ASA for the client's IP last octet was either a 0 or 255.
>> Since I am announcing our network as a /19, the subnet mask is 255.255.224.0, that would make our network address x.x.192.0 and the broadcast x.x.223.255.
>> So somewhere the /24 boundary addresses were being dropped.
>>
>> Just curious if anyone else has seen this before.
>
> some OS's by M and others as well as some devices have IP stacks which
> will not send or receive unicast packets ending in 0 or 255.  have had
> casses where someone was doing subnets that included those in the DCHP
> scopes and the computers that received these addresses were black
> holes.
>
> james

MSKB 281579 affects XP home and below. Good times anytime someone adds
a .0 or .255 into an IP pool.



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