[c-nsp] BGP Route Announcement

[Bryan Holloway]

I generally prefer to keep the Null0 even if there's a static or (IGP) 
non-static as a matter of best-practice.

If your IGP burbles, then the rest of the Internet won't, leading to 
faster recovery times.

Statics are inherently less prone to this, but having the Null0 pin-up 
doesn't hurt anything and it makes your configuration more homogeneous 
knowing that anything you're advertising should be in the routing table 
no matter what. Easier to trouble-shoot, spot errors, etc.


On 12/14/18 2:40 PM, Shawn L wrote:
> That second part has bit me in the rear before..... As a matter of course
> now I always make a static route to null 0 for every prefix I announce via
> BGP.  Once I verify that an IGP or static route is covering that prefix, I
> remove the null route.... or not if you have several more specific routes.
> 
> On Fri, Dec 14, 2018 at 12:34 PM Mark Tinka <mark.tinka at seacom.mu> wrote:
> 
>>
>>
>> On 14/Dec/18 19:16, Joseph Mays wrote:
>>
>>>
>>> The distribute lists shown also just contained appropriate permit and
>> deny entries for 216.24.0.0 /18
>>
>> Firstly, please don't use distribute lists. This is very archaic and
>> prone to mistakes. Suggest you migrate to prefix lists right away!
>>
>>>
>>>
>>> That changed the broadcast cogent was receiving, but not in the expected
>> way. They only route they saw us broadcasting after that was the
>> 216.24.60.0/23 route. Not the first one in the list, not the last one,
>> not the biggest one or the smallest one, but just one route from the middle
>> of the list. I don't get this behavior at all. Cogent cleared and bounced
>> bgp to us, and still received only that one route in the broadcast from us.
>>
>> After you've fixed your filtering with prefix lists, you need to ensure
>> that any "network..." statement is backed up by the presence of the very
>> same route in your IGP (which includes static routing).
>>
>> Mark.
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