DM: configure unit on lo0 interface for L3 only VNs

[Nischal Sheth]

If the forwarding mode for a VN is l2_l3, DM allocates IP address from
each VN subnet and configures them on an IRB IFL that belongs to the
L3 VRF for the VN. This functionality was implemented via bug 1465070.

Along similar lines, if the forwarding mode for a VN is l3, DM needs to
allocate IP address from each VN subnet and configure them on a lo0
IFL that belongs to the L3 VRF for the VN. This will be useful to test
connectivity between the VRF and a VM.

Note that the addresses for each lo0 unit must be persisted, pretty much
the same way that IRB addresses are persisted.

Unit number for the lo0 IFL can be calculated based on the VN index.
However, instead of using the VN index directly as the unit number,
we should calculate it using a fixed offset, say 1000 + VN index. This
is to avoid conflict with lo0.0 (which is typically configured by user)
and to have some unit numbers available for users for manual config.

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/23393
Submitter: Suresh Balineni (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/25796
Submitter: Suresh Balineni (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/25796
Committed: http://github.org/Juniper/contrail-controller/commit/644dd9b9b5de1033ab0fe8ed8e32c2719045a640
Submitter: Zuul
Branch: master

commit 644dd9b9b5de1033ab0fe8ed8e32c2719045a640
Author: sbalineni <email address hidden>
Date: Mon Nov 7 16:32:01 2016 -0800

[DM]: Allocate ip from each subnet of VN for lo0 interface

- allocate ip from each subnet of VN (non-external L3 VNs) and configure lo0 interface
- lo0 interface ifl unit number is calculated as 1000 + vn_id
- for now, do not allocate this ip if vn is type external
- persist allocated IPs in DB, and on restart use same allocated ips
- on delete, free up allocated ips
- Cassandra Key indexing format is changed for supporting both irb & lo0
- Upgrade issue is taken care
- Added UT cases
- Fixed ip_alloc recent regression issue (bad parameter was passed to virtual_network_ip_alloc api)

Generated Config:

root@cmbu-tasman# show groups __contrail__ interfaces lo0 | display set
set groups __contrail__ interfaces lo0 unit 0 family inet address 172.16.184.200/32 primary
set groups __contrail__ interfaces lo0 unit 0 family inet address 172.16.184.200/32 preferred
set groups __contrail__ interfaces lo0 unit 1210 family inet address 40.0.0.6/32

[edit]
root@cmbu-tasman# show groups __contrail__ interfaces lo0 | display xml
<rpc-reply xmlns:junos="http://xml.juniper.net/junos/14.2R6/junos">
<configuration junos:changed-seconds="1471546906" junos:changed-localtime="2016-08-18 12:01:46 PDT">
<groups>
<name>__contrail__</name>
<interfaces>
<interface>
<name>lo0</name>
<unit>
<name>0</name>
<family>
<inet>
<address>
<name>172.16.184.200/32</name>
<primary/>
<preferred/>
</address>
</inet>
</family>
</unit>
<unit>
<name>1210</name>
<family>
<inet>
<address>
<name>40.0.0.6/32</name>
</address>
</inet>
</family>
</unit>
</interface>
</interfaces>
</groups>
</configuration>
<cli>
<banner>[edit]</banner>
</cli>
</rpc-reply>

Change-Id: I2104b0f5a2f72c824e1e14e464271b7bb44106f5
Closes-Bug: #1491506