Use bgp_aigp instead of bgp_med to select the optimal route based on delay

[Brandon Zhi]

Hi Ondrej,


   as.path.len = 2                                          as.path.len = 1
Upstream1 ---- Node1 ---(10ms) Node2 --(20ms)-- Upstream2
                                           |
                                        Node3


For this network situation, I need to have node 3 go to node 2 and connect
to the internet through upstream 1. Even if its as.path is longer.
Therefore, a parameter with a priority greater than as.path.len is required
to achieve this.

Best,
*Brandon Zhi*
HUIZE LTD
www.huize.asia  <https://huize.asia/>| www.ixp.su | Twitter

This e-mail and any attachments or any reproduction of this e-mail in
whatever manner are confidential and for the use of the addressee(s) only.
HUIZE LTD can’t take any liability and guarantee of the text of the email
message and virus.


On Tue, 10 Oct 2023 at 21:43, Ondrej Zajicek <santiago at crfreenet.org> wrote:

> On Mon, Oct 09, 2023 at 11:29:33PM +0800, Brandon Zhi wrote:
> > Hi all,
> >
> > I plan to use bgp_aigp instead of bgp_med to find the optimal route based
> > on incremental pings per node. For example, if the delay between one node
> > and another node is 40, then bgp_aigp increases by 40 after passing this
> > ibgp.
> >
> > void bgp_aigp [O]
> > This attribute contains accumulated IGP metric, which is a total
> > distance to the destination through multiple autonomous systems.
> > Currently, the attribute is not accessible from filters.
> >
> > But it seems I can't modify this value?
>
> Hi
>
> You cannot modify bgp_aigp - total distance, but you can modify per-hop
> distance, which is added to it automatically in each (inter-AS) step.
>
> It is either regular IGP metric (e.g. the attribute 'ospf_metric1' in
> case of OSPF), or manually configured one (the attribute 'igp_metric'),
> or configured cost of inter-AS link [0].
>
> [0] https://bird.network.cz/?get_doc&v=20&f=bird-6.html#bgp-cost
>
> I think that using bgp_aigp is the right tool for your use case, but
> details depend on specific topology of your confederation - whether each
> internal AS in the confederation is nontrivial network with IGP, flat
> network, or just one router.
>
> --
> Elen sila lumenn' omentielvo
>
> Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
> OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
> "To err is human -- to blame it on a computer is even more so."
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://trubka.network.cz/pipermail/bird-users/attachments/20231013/36f176be/attachment.htm>