Re: OpenBGP filter question
On 12.2.2010 P3. 11:10, Stuart Henderson wrote:
On 2010-02-11, Ivo Chutkinopen...@bgone.net wrote:
match to $my_upstream_1 source-as {some_as} set prepend-self 4
I would like to prepend my as to make as path longer for some_as
trough my_upstream_1 and make it to prefer path trough my_upstream_2.
It does not produce error with bgpd-n but there is no effect as well.
Are you certain it has no effect (and how?) - you can't rely on
AS path prepending to change how traffic flows, if someone gives you
a higher localpref they'll use that path irrespective of the path length.
Hi Stuart,
I am certain as I don't see my prepend on some_as looking glass.
The actual filter looks like this without the comment:
match to $spnet_bg #(AS8717) sourse_as 9070 set prepend-seff 4
and this is what I see on 9070 looking glass:
This filter affects prefixes you send to the peer, and only those
with source_as 9070. Unless you are providing transit for 9070
you won't be sending anything to 34224 that matches this (and if
you are, it wouldn't be a useful thing to do, as 9070 won't
accept routes with their own AS in the path).
If I understand correctly, you'd like 9070 to see a longer path
to you via 34224, but not affect things for other AS that see you
via 34224.
I think there are just two ways you can do this via prepending
1. ask 34224 to prepend their announcements to 9070.
Some providers let you set communities on your prefixes to
do this, see e.g. whois -r as3356|more +/ties.acc
but many do not.
2. ask 9070 to prepend the paths they receive from 34224.
Hi Stuart, hi list,
Sorry for being away for so long.
You get me correct, that is what I wanted to achieve. The as 9070 is
just an example. Obviously it is not the correct way to do it.
Thank you for clarifying it for me.
Regards,
Ivo
Re: OpenBGP filter question
On 2010-02-11, Ivo Chutkin open...@bgone.net wrote:
match to $my_upstream_1 source-as {some_as} set prepend-self 4
I would like to prepend my as to make as path longer for some_as
trough my_upstream_1 and make it to prefer path trough my_upstream_2.
It does not produce error with bgpd-n but there is no effect as well.
Are you certain it has no effect (and how?) - you can't rely on
AS path prepending to change how traffic flows, if someone gives you
a higher localpref they'll use that path irrespective of the path length.
Hi Stuart,
I am certain as I don't see my prepend on some_as looking glass.
The actual filter looks like this without the comment:
match to $spnet_bg #(AS8717) sourse_as 9070 set prepend-seff 4
and this is what I see on 9070 looking glass:
This filter affects prefixes you send to the peer, and only those
with source_as 9070. Unless you are providing transit for 9070
you won't be sending anything to 34224 that matches this (and if
you are, it wouldn't be a useful thing to do, as 9070 won't
accept routes with their own AS in the path).
If I understand correctly, you'd like 9070 to see a longer path
to you via 34224, but not affect things for other AS that see you
via 34224.
I think there are just two ways you can do this via prepending
1. ask 34224 to prepend their announcements to 9070.
Some providers let you set communities on your prefixes to
do this, see e.g. whois -r as3356|more +/ties.acc
but many do not.
2. ask 9070 to prepend the paths they receive from 34224.
Re: OpenBGP filter question
Am 11.02.2010 11:31, schrieb Ivo Chutkin:
The actual filter looks like this without the comment:
match to $spnet_bg #(AS8717) sourse_as 9070 set prepend-seff 4
These are typos, right?
match to neighborip source-as as to prepend set { prepend-self 3 }
works in our setup
Re: OpenBGP filter question
On 10.2.2010 P3. 21:32, Stuart Henderson wrote:
On 2010-02-10, Ivo Chutkinopen...@bgone.net wrote:
Hello misc,
Would the following filter work?
match to $my_upstream_1 source-as {some_as} set prepend-self 4
I would like to prepend my as to make as path longer for some_as
trough my_upstream_1 and make it to prefer path trough my_upstream_2.
It does not produce error with bgpd-n but there is no effect as well.
Are you certain it has no effect (and how?) - you can't rely on
AS path prepending to change how traffic flows, if someone gives you
a higher localpref they'll use that path irrespective of the path length.
Hi Stuart,
I am certain as I don't see my prepend on some_as looking glass.
The actual filter looks like this without the comment:
match to $spnet_bg #(AS8717) sourse_as 9070 set prepend-seff 4
and this is what I see on 9070 looking glass:
inet.0: 5185 destinations, 8315 routes (5184 active, 0 holddown, 1 hidden)
+ = Active Route, - = Last Active, * = Both
A DestinationP Prf Metric 1 Metric 2 Next hopAS path
* 87.120.100.0/24B 170115212.116.129.38 34224
20682 I
B 170115 99 212.116.129.66 34224
20682 I
B 170115212.116.135.81 8717
20682 I
{master:0}
where 20682 is my as.
Filter like:
match to $spnet_gl prefix {$net3 $net4 $net5 $net6} set prepend-self 2
works perfect but it prepends all as paths from this neighbor and it
changes the routes to me.
I am aware of local preference.
Thanks for the help,
Ivo
OpenBGP filter question
Hello misc,
Would the following filter work?
match to $my_upstream_1 source-as {some_as} set prepend-self 4
I would like to prepend my as to make as path longer for some_as
trough my_upstream_1 and make it to prefer path trough my_upstream_2.
It does not produce error with bgpd-n but there is no effect as well.
Thanks for the help,
Ivo
Re: OpenBGP filter question
On 2010-02-10, Ivo Chutkin open...@bgone.net wrote:
Hello misc,
Would the following filter work?
match to $my_upstream_1 source-as {some_as} set prepend-self 4
I would like to prepend my as to make as path longer for some_as
trough my_upstream_1 and make it to prefer path trough my_upstream_2.
It does not produce error with bgpd-n but there is no effect as well.
Are you certain it has no effect (and how?) - you can't rely on
AS path prepending to change how traffic flows, if someone gives you
a higher localpref they'll use that path irrespective of the path length.
