Hello On Mon, Oct 06, 2008 at 02:53:27PM +0200, Martin Mares wrote:
Variable 'bgp_as4_support' decides whether this router support 4B ASN or not. It is possible to disable 4B ASN support (using global option 'disable_bgp_as4') (for example for testing or to workaround a bug in the neighbor implementation of 4B ASN) but it shouldn't be neccessary to change this setting. When bgs_as4_support is enabled, then native representation of AS_PATH (type EAF_TYPE_AS_PATH) is 4 B per ASN, otherwise it is 2 B per ASN.
I would really like to have this configurable per protocol instance -- when you want to work around a bug, you usually do not wish to disable the feature for the whole router, but only for the particular neighbor.
I will think about it.
The extended attribute AS4_PATH is used only when 4B-aware and 4B-non-aware routers communicate together. If BIRD is 4B-aware, then it discards such attribute ASAP, and when BIRD is not 4B-aware, it is opaque attribute for it.
I have missed the fact that the attribute is only temporary at the first reading.
As a temporary attribute, it can well be opaque, but we should convert it to a common fixed format as soon as possible.
It is not converted - if BIRD is 4B-aware, then it is used (together with 2B AS_PATH) to reconstruct real AS_PATH and then immediately discarded. if BIRD is not 4B-aware, then BIRD should handle it as unknown optional transitive atribute. -- Elen sila lumenn' omentielvo Ondrej 'SanTiago' Zajicek (email: santiago@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."