set_local_pref not flexible enough

[fldardenne]

Hi,

The set_local_pref function from bgp.py aims to change the local-preference attribute if the route matches the community or an AccessList.

ipmininet/ipmininet/router/config/bgp.py

Line 151 in 693f3b7

def set_local_pref(self, local_pref: int, from_peer: str,

To do so, the function creates a route-map in the router and links this route-map with the "from_peer" neighbor.

However, I noticed some problems:

• The new route-map linked to the neighbor blocks all the other routes that do not match the CommunityList/AccessList.
• We cannot set the same route-map with different orders.
• If we try to set multiple local-pref with multiple Communities, it does not add a new route-map with different orders but appends the new "match" condition and appends the new "set local-preference" in the existing route-map.

What I suggest as a solution and that I applied in the project is to give more flexibility to this function :

• An optional parameter to define the name, the function will format it as "name+adressFamily". If None is given, take the actual strategy (check if an existing route-map can take the "match" and the "set local-preference" - if not, a new route-map with the name rm%d is created)
• An optional parameter to define the order (actually hardcoded to 10)

With those two new parameters, the user can now define a succession of route-maps to define multiple local-pref matching some communities and finally set a default local-pref so that these route maps do not block others route.

If this solution is accepted, I can do a pull request for my implementation to solve these issues. If a better solution is proposed, I am willing to volunteer for the implementation of that one.

[fldardenne]

An optional parameter to define the order (actually hardcoded to 10)

But when creating a new route-map (let's call it rm11), the first route-map order should be set to 10. Or it will not be linked to the neighbor due to the bgpd.mako condition.

ipmininet/ipmininet/router/config/templates/bgpd.mako

Line 29 in 693f3b7

% if rm.neighbor.family == af.name and rm.order == 10:

Then afterward, the user can create other rm11 route-map with different order.

[jadinm]

Hello,

However, I noticed some problems:

• The new route-map linked to the neighbor blocks all the other routes that do not match the CommunityList/AccessList.
• We cannot set the same route-map with different orders.
• If we try to set multiple local-pref with multiple Communities, it does not add a new route-map with different orders but appends the new "match" condition and appends the new "set local-preference" in the existing route-map.

Could you provide a minimal example for each of the issues that you noted ?
For instance, a minimal topology with two BGP routers and maybe show the configuration that is produced.

Then, it would be easier to understand what the problem is and I will be able to provide feedback on your suggested solution ;-)