From: Hyunseog Ryu (r.hyunseog@ieee.org)
Date: Sun Jul 29 2007 - 17:28:53 ART
Upstream providers will remove private AS number when they readvertise
to other ISPs.
So natually if you have multi-homed to multiple ISPs, the route will be
appeared as inconsistent ORIGIN AS, which will not appeared as valid
route from RFC viewpoint.
According to RFC - I don't remember which -, it should be originated
from single AS number.
Also, customer who uses Private ASN with multiple upstream providers can
NOT implement consistent routing policy for that matter.
So multihomed customer with private ASN is not recommended for multiple
providers upstream connection.
If customer have multiple connections with SAME providers, they may use
private ASN for load sharing purpose.
Hyun
Gregory Gombas wrote:
> What are you losing by using a private ASN? You can still advertise
> your own dedicated IP address space via both providers can't you? Your
> ISP's simply needs to remove that private AS when passing the update
> to other ISP's...
>
> Am I missing something here?
>
> On 7/29/07, Herbert Maosa <asawilunda@googlemail.com> wrote:
>
>> If you dont have your own ASN, you will most likely have to use a private
>> ASN to connect to the two ISPs. Remember that if you use the ISPs ASN then
>> you are an extension of that ISP. Using the private ASN in this case will
>> permit you to be totally provider independent.
>>
>> regards,
>>
>> Herbert.
>>
>>
>> On 7/29/07, Gregory Gombas <ggombas@gmail.com> wrote:
>>
>>> When connecting to the internet via two different ISP's, why is it
>>> necessary to have a unique AS?
>>>
>>> What if you simply configured your BGP router with the same AS number
>>> as one of your ISP's?
>>>
>>> Considering there are only 64511 unique AS numbers, I assume that most
>>> if not all the AS numbers are already taken. What do companies do in
>>> the case they cannot get their own AS number and need to multihome?
>>>
>>> Thanks,
>>> Greg
>>>
>>>
>>>
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>>
>> --
>> Kindest regards,
>> hm
>>
>
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