Background: We own /24 as well as /23 blocks provider independent.
I am talking to an ISP, say ISP-A for a 10G line with a IPVPN line (2 links - actual inbound + IPVPN link for clean traffic when there is a attack) for DDOS mitigation. When there is a attack my ISP filters the attack the send the clean traffic through IPVPN. This is a proposal.
For redundancy purpose, we are planning to have an another ISP-B but still want to use the ISP-As DDOS mitigation. When we asked this, ISP-A said, we cannot do mitigation for blocks less than /24, technically they cannot advertise less than /24 due some memory issues etc and said it is kind of internet limitation not BGP or theirs(ISP-A).
Can anyone explain more on it?