regarding routing, the suggestion is to move the route entries in the interfaces file from the vrouter interface to the vhost0 interface in the vrouter installation script.

Currently, the vrouter.cfg file looks like this for a multi-interface, L3 fabric environment after vrouter installation:

root@ic-skbrat2-cz37486c8s:~# cat /etc/network/interfaces.d/vrouter.cfg 
###############################################################################
# [ WARNING ]
# Configuration file maintained by Juju. Local changes may be overwritten.
###############################################################################

auto bondB
iface bondB inet manual
    bond-lacp-rate fast
    bond-miimon 100
    bond-mode 802.3ad
    bond-num-grat-arp 1
    bond-slaves none
    bond-xmit-hash-policy layer2
    hwaddress 48:df:37:21:ed:98
    mtu 9134
    post-up route add -net 100.80.39.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.39.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.59.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.59.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.69.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.69.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.38.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.38.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.48.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.48.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.58.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.58.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.68.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.68.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true

auto vhost0
iface vhost0 inet static
    address 100.80.49.1/24
    pre-up ip link add address $(cat /sys/class/net/bondB/address) type vhost
    pre-up vif --add bondB --mac $(cat /sys/class/net/bondB/address) --vrf 0 --vhost-phys --type physical
    pre-up vif --add vhost0 --mac $(cat /sys/class/net/bondB/address) --vrf 0 --type vhost --xconnect bondB
    post-down vif --list | awk '/^vif.*OS: vhost0/ {split($1, arr, "\/"); print arr[2];}' | xargs vif --delete
    post-down vif --list | awk '/^vif.*OS: bondB/ {split($1, arr, "\/"); print arr[2];}' | xargs vif --delete
    post-down ip link delete vhost0


The file should look like this after vrouter installation - making sure the configuration is persitent across reboots etc:

root@ic-skbrat2-cz37486c8s:~# cat /etc/network/interfaces.d/vrouter.cfg     
###############################################################################
# [ WARNING ]
# Configuration file maintained by Juju. Local changes may be overwritten.
###############################################################################

auto bondB
iface bondB inet manual
    bond-lacp-rate fast
    bond-miimon 100
    bond-mode 802.3ad
    bond-num-grat-arp 1
    bond-slaves none
    bond-xmit-hash-policy layer2
    hwaddress 48:df:37:21:ed:98
    mtu 9134

auto vhost0
iface vhost0 inet static
    address 100.80.49.1/24
    pre-up ip link add address $(cat /sys/class/net/bondB/address) type vhost
    pre-up vif --add bondB --mac $(cat /sys/class/net/bondB/address) --vrf 0 --vhost-phys --type physical
    pre-up vif --add vhost0 --mac $(cat /sys/class/net/bondB/address) --vrf 0 --type vhost --xconnect bondB
    post-down vif --list | awk '/^vif.*OS: vhost0/ {split($1, arr, "\/"); print arr[2];}' | xargs vif --delete
    post-down vif --list | awk '/^vif.*OS: bondB/ {split($1, arr, "\/"); print arr[2];}' | xargs vif --delete
    post-down ip link delete vhost0
    post-up route add -net 100.80.39.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.39.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.59.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.59.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.69.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.69.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.38.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.38.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.48.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.48.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.58.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.58.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    post-up route add -net 100.80.68.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true
    pre-down route del -net 100.80.68.0 netmask 255.255.255.0 gw 100.80.49.254 metric 0 || true