DM: support L2 and L3 configuration for external VNs

[Nischal Sheth]

Current implementation does not generate L2 routing-instance configuration
for external VNs. This limitation needs to be removed to support use cases
where there are external VNs with BMSs.

The following changes need to be made:

1. Decision to generate L2 routing-instance configuration or not must be
made based on the VN forwarding-mode (see bug 1471637) rather than the
external flag. L2 configuration must not be generated if the forwarding
mode is L3 only.

2. Static routes for external VN prefixes should be added to inet.0 to
allow user to export these prefixes into the routing protocol used for
inet.0. These routes should have a discard next-hop since JUNOS does not
allow 2 tables with static routes (even if the prefixes are different) to
have table next-hops pointing to each other. Static routes can either be
added as primary routes to inet.0 or by creating a rib-group for each
external VN and applying rib-group to static routes added in corresponding
VRF. The former should be the first choice.

Note that the L3 routing-instance configuration for an external VN already
has static default route with a table next-hop that points to inet.0. This
is used to forward traffic coming in from BMSs to the external VRF. There
will be no change to this configuration.

3. Note that the static discard routes in inet.0 added as part of 2 above
will not be used for forwarding, only for route export. Traffic coming in
to inet.0 will be directed to the appropriate VRF based on the forwarding
table filter that's applied to inet.0. This filter is currently generated
but it's not clear if it supports > 1 external VNs. Instead of creating a
filter per external VN, a single filter must be created. This filter will
should have a term for each external VN. The term should match prefixes in
the external VN and redirect the traffic to routing-instance in question.

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/13524
Submitter: Suresh Balineni (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/13524
Committed: http://github.org/Juniper/contrail-controller/commit/140154bdf72baf76ae56cc9060b3df46cf349cc6
Submitter: Zuul
Branch: master

commit 140154bdf72baf76ae56cc9060b3df46cf349cc6
Author: sbalineni <email address hidden>
Date: Tue Sep 1 17:33:28 2015 -0700

DM: VRF instances are configured based on VN forwarding mode

- VN forwarding mode {l2, l2_l3} - Configure L2 VRF
- VN forwarding mode {l3, l2_l3} - Configure L3 VRF
- L2 VRF will only have interface config
- IRB interfaces, irb ip allocation is done only if fwd mode is 'l2_l3'
- For all external VNs subnets, add a static route in global
forwarding options
- for all L3 vrf instances, static routes with discard nexthops are added.

Change-Id: I860fb6c59b85391e667554d8b57602f24cd14e48
Closes-Bug: #1472699

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/13668
Submitter: Suresh Balineni (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/13668
Committed: http://github.org/Juniper/contrail-controller/commit/1713ce221a09497a792146a716eeb81fed382514
Submitter: Zuul
Branch: R2.20

commit 1713ce221a09497a792146a716eeb81fed382514
Author: sbalineni <email address hidden>
Date: Tue Sep 8 10:28:49 2015 -0700

DM: VRF instances are configured based on VN forwarding mode

- VN forwarding mode {l2, l2_l3} - Configure L2 VRF
- VN forwarding mode {l3, l2_l3} - Configure L3 VRF
- L2 VRF will only have interface config
- IRB interfaces, irb ip allocation is done only if fwd mode is 'l2_l3'
- For all external VNs subnets, add a static route in global
forwarding options
- for all L3 vrf instances, static routes with discard nexthops are added.

Change-Id: I4832b5036c9aecf3ae25187d4bd88018f08af7bc
Closes-Bug: #1472699

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/13922
Submitter: Suresh Balineni (<email address hidden>)