Hi all,
Sorry, it's my ambiguous description. What I said default value is Cisco's
admin distance value, eBGP is 20 and iBGP is 200. We plan to use preference to
implement admin distance. Actually ,in bird, the preference of channel for
BGP is BGP protocol default preference DEF_PREF_BGP ( = 100).
1) Since the configuration of preference is in channel ,if the protocol
have more than one channel, does mean different channel can configure different
preference in the same protocol ?
2) I also notice that " new->pref = c->preference; " in rte_update2, does
mean the preference of route in route table get from preference of channel ?
3) When route selection, does mean algorithm selection compare preference
of every route firstly , whether compare the preference of routes coming from
same protocol ?
The global best route selection algorithm is (roughly) as follows: ---> Does
routes selection be processed as below sequence ?
* Preferences of the routes are compared. ----> what's preference of the
route, is preference in channel-config ?
* Source protocol instance preferences are compared. --> what's protocol
instance preference, is preference in channel-config for BGP protocol instance?
* If source protocols are the same (e.g. BGP vs. BGP), the protocol's
route selection algorithm is invoked. --->source protocols, iBGP and eBGP are
treated as same source protocol ?
* If source protocols are different (e.g. BGP vs. OSPF), result of the
algorithm is undefined.
The Admin distance of Cisco for eBGP and iBGP:
https://supportforums.cisco.com/t5/wan-routing-and-switching/administrative-distance-and-bgp-path-selection-process/td-p/2276230
Thanks
Arvin
-----Original Message-----
From: Bird-users <bird-users-boun...@network.cz> On Behalf Of Robert Blayzor
Sent: Tuesday, April 17, 2018 10:07 PM
To: bird-users@network.cz
Subject: Re: BGP route selection
On 4/17/18 8:20 AM, Ondrej Zajicek wrote:
> Hi
>
> No, default value is 200 for both EBGP and IBGP. Where did you noticed 20?
20 is Cisco's default admin distance for EBGP.
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