[j-nsp] BGP export policy, group vs neighbor level

[Raph Tello]

Hey,

not really clear to me what that KB is exactly saying.

Does it say:

a) Peer will be reset when it previously hadn’t an individual import/export
policy statement but the group one and then an individual one is configured

b) Peer will be reset each time it‘s individual policy is touched while
there is another policy in the group

or

c) Peer is reset the first time it receives it‘s own policy under the group

Unfortunate that this seems to be not really well documented.


On Fri 4. Feb 2022 at 20:15, Andrey Kostin <ankost at podolsk.ru> wrote:

> Hi,
> this KB article just came in:
>
> https://kb.juniper.net/InfoCenter/index?page=content&id=KB12008&actp=SUBSCRIPTION
> Symptoms:
> Why does modifying a policy on a BGP neighbor in a group cause that
> particular peer to be reset, when another policy is applied for the
> whole peer group?
> Solution:
> Changing the export policy on a member (peer) in a group will cause that
> member to be reset, as there is no graceful way to modify a group
> parameter for a particular peer. Junos can gracefully change the export
> policy, only when it is applied to the complete group.
>
> It's not much helpful but just provides a confirmation.
>
> Kind regards,
> Andrey
>
> Raph Tello via juniper-nsp писал(а) 2022-02-04 09:33:
> > I would also like to hear opinions about having ipv4 and ipv6 ebgp peer
> > sessions in the same group and using the same policy instead of having
> > two
> > separate groups and two policies (I saw this kind policy at
> > https://bgpfilterguide.nlnog.net/guides/small_prefixes/#junos).
> >
> > It would nicely pack things together. Could that be considered kind of
> > new
> > best practice?
> >
> > On Thu 3. Feb 2022 at 16:12, Raph Tello <telloraph at gmail.com> wrote:
> >
> >> Hi list,
> >>
> >> I wonder what kind of bgp group configuration would allow me to change
> >> the
> >> import/export policy of a single neighbor without resetting the
> >> session of
> >> this neighbor nor any other session of other neighbors. Similar to
> >> enabling/disabling features on a single session without resetting the
> >> sessions of others.
> >>
> >> Let‘s say I have a bgp group IX-peers and each peer in that group has
> >> its
> >> own import/export policy statement but all reference the same
> >> policies. Now
> >> a single IX-peer needs a different policy which is going to change
> >> local-pref, so I would replace the policy chain of that peer with a
> >> different one.
> >>
> >> Would this cause a session reset because the peer would be moved out
> >> of
> >> the update group?
> >>
> >> (I wonder mainly about group>peer>policy vs. group>policy vs. each
> >> peer
> >> it‘s own group)
> >>
> >> - Tello
> >>
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