1. Jessica Yu ANS Communication Inc. Feb. 9th, 1998
A Routing Filtering Model for Improving Global Routing Robustness an IOPS proposal
Jessica Yu
ANS Communication Inc.
Feb. 9th, 1998

2. Background
Internet suffered a series of outages as a result of leakage of ‘bad’ routing information
IOPS identifies a mechanism to improve routing system robustness
IOPS encourages its member and other ISPs to implement it

3. What’s the Problem?
Current global routing system is open thus vulnerable
‘Bad’ routing information injecting from anywhere of the Internet will be propagated allover resulting outages (one dead mouse spoils the whole pot of soup)
Proven by several incidents occurred - unfortunately

4. What’s the Problem? (con’t)
Could happen due to misconfiguration, software bugs or malicious attempt
The ‘openness’ can be potentially used by attackers to inject routes for denial of service attacks such as smurf attack

5. Current Picture: Vulnerable

6. Bad routing information can cause big outage

7. IOPS Goals
To identify or define mechanism to improve global routing robustness
Using existing technology as much as possible so it can be implemented fast since the problem is an urgent one

8. The Routing Filtering Model
Sparse filtering on ‘trusted’ and Dense filtering on ‘less-trusted’ routing boundaries
Trusted routing boundary - the peer does dense filtering at all of its customers boundaries and all of it’s downstream providers implement such routing filtering model
Otherwise, it’s less-trusted boundary
This is mainly verify against the border AS which advertising the route

9. Scenario 1: All ISPs Dense Filter customers

10. Scenario 2: Some ISPs do not dense filter customers, immediate upstreams have to

11. Scenario 3: ISP does not dense filter less-trusted downstream ISPs, peer have to

12. Benefits
bad routes will be stopped from propagating near or at its source thus reduce impact to a small scope of the Internet
Attackers has less chance to introduce routes on the fly to the whole Internet and launch attacks
To localize the impact of the ‘bad’ routes
To Reducing the weakness which potentially will be explored by attackers
The more ISPs or AS implement this model the better protection we have
The more ISP does this, the less work everyone need to do (
less boundaries needs dense filtering, and
shorter prefix each has to manage

13. Tools
The key to this is to maintain an prefix list to generate filtering list on the border routers
Private database which install customer to be announced prefix
IRR
Other means

14. Issues how to validate if someone is entitled to advertise a route
Provider check its customers route match with address assignment information
Add features in IRR to validate such information in combination with assignment information (working under way)

15. Future work
This work was done 6 months ago which at the time was the best viable option
This is model of checking against neighbor AS, another model is to check against the Origin AS
If there is other viable proposal which will address the problem better, will consider that.