Topic: Inter-AS BGP Local Preference Matrix

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1

My company is building a national backbone network, leveraging leased lines and dark fiber from Tier 1/2/3 providers. What we've found is that when we buy IP in the major markets, our traffic does not flow deterministically with AS-Path as the metric. This is because most of the major providers give their customers one local preference value, and their peers another, in an effort to ensure SLAs are met by keeping customer traffic on-net for as long as possible. There are varying values assigned, and some vendors don't offer community values to neutralize this effect.

I'm wondering if anyone has dealt with this in the past, or if it would be possible to have some sort of agreement on local preference manipulation. Something similar to the below:

1. All vendors must offer at least 5 community values for local preference. This is to allow for customer-based multivendor traffic engineering.
2. All vendors must offer a local preference community value greater than their best default metric.
3. All vendors must offer a local preference community value lesser than their worst default metric.
4. All vendors should offer a range of community values both above and below local preference 100.
5. All vendors should make an effort to standardize the values/value ranges offered with other vendors.
6. All vendors should offer a local preference matrix to their customers, listing the changes made to a specific AS (e.g. another vendor) to aid the customer in making an intelligent routing decision for load balancing and traffic engineering in a multivendor BGP environment.

It's obviously something that each of us would need to do individually, but I'm wondering if there is any way this could become a de facto standard, or could be a method that the community at large could enforce somehow.

Sincerely,

Brian A . Rettke
RHCT, CCDP, CCNP, CCIP
Network Engineer, CableONE Internet Services

2

My company is building a national backbone network, leveraging leased lines and dark fiber from Tier 1/2/3 providers. What we've found is that when we buy IP in the major markets, our traffic does not flow deterministically with AS-Path as the metric. This is because most of the major providers give their customers one local preference value, and their peers another, in an effort to ensure SLAs are met by keeping customer traffic on-net for as long as possible. There are varying values assigned, and some vendors don't offer community values to neutralize this effect.

I think you mean "provider" rather than "vendor"; by and large, all
hardware vendors provide
some knob to allow for changing localpreference values across the full
range of allowable values.

Providers, on the other hand, only allow customers to request a change
of local preference
values, and then only among a very small set of values, usually
ranging from "above normal
customer localpref", "default customer localpref", and "below customer
localpref". If you're
really lucky, they might allow you to set "peer localpref" and "below
peer localpref".

I'm wondering if anyone has dealt with this in the past, or if it would be possible to have some sort of agreement on local preference manipulation. Something similar to the below:

1. All vendors must offer at least 5 community values for local preference. This is to allow for customer-based multivendor traffic engineering.
2. All vendors must offer a local preference community value greater than their best default metric.
3. All vendors must offer a local preference community value lesser than their worst default metric.
4. All vendors should offer a range of community values both above and below local preference 100.

Not everybody uses 100 as their default value, so that requirement
could be at odds with the
rest of the requirements. I'd recommend dropping that from your list,
to make the barrier to
adoption lower.

5. All vendors should make an effort to standardize the values/value ranges offered with other vendors.
6. All vendors should offer a local preference matrix to their customers, listing the changes made to a specific AS (e.g. another vendor) to aid the customer in making an intelligent routing decision for load balancing and traffic engineering in a multivendor BGP environment.

It's obviously something that each of us would need to do individually, but I'm wondering if there is any way this could become a de facto standard, or could be a method that the community at large could enforce somehow.

I'm not sure what incentive there would be for the providers to
coordinate like this;
it would mean quite a bit more work for them, with no appreciable gain
in revenue
for it.

Matt

3

not to mention the sloshing of traffic to get to a standard... weee!

4

Alice's Restaurant.

If one customer asks for it, if two ask for it, if 50 ask for it...

Just put your requirements into the RFP, and make it clear your $$ are going to
the outfit that does the best on your list of 6 requirements. Remind the
losers of this. Get 49 of your friends to put it in RFP's too. The providers
are *not* going to do something like this unless there's a good economic basis
for doing it.