From the freertr website:

freeRouter is a free, open source router os process it speaks routing protocols, and (re)encapsulates packets on interfaces (a huge list of encapsulation and routing test cases can be found under self-test page)since it handles packets itself, it is independent of underlaying os capabilities(optionally, it can export forwarding tables through openflow to external switch)since it is an unprivilegized process, it receives and sends packets through socketsthere are external, privileged processes that place traffic to these sockets(it means that internet can be used as backplane for router processes) the command line tries to mimic the industry standards with one exception: no global routing table: every routedinterface must be in a virtual routing table positive side effect: there are no vrf-awareness questions

As notes in my FreeRTR post, FreeRTR is a wonderful alternative to labbing up protocols and provides an incredible array of protocol support. Below are my three router test configurations from a basic setup. They should be enough to get you started.

RTR1

 
hostname rtr1 
buggy 
! 
! 
vrf definition host 
exit 
! 
vrf definition vrf1 
rd 1:1 
exit 
! 
router isis4 1 
vrf vrf1 
net-id 48.1111.0000.1111.00 
traffeng-id :: 
is-type both 
redistribute connected 
exit 
! 
router isis6 1 
vrf vrf1 
net-id 48.1111.0000.1111.00 
traffeng-id :: 
is-type both 
segrout 10 
level2 segrout 
level1 segrout 
redistribute connected 
exit 
! 
! 
interface loopback0 
no description 
vrf forwarding vrf1 
ipv4 address 10.99.99.1 255.255.255.255 
ipv6 address 2001:db8:1111::1 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 
router isis6 1 enable 
router isis6 1 circuit both 
router isis6 1 segrout index 1 
router isis6 1 segrout node 
no shutdown 
no log-link-change 
exit 
! 
interface loopback1 
no description 
no shutdown 
no log-link-change 
exit 
! 
interface ethernet1 
no description 
lldp enable 
vrf forwarding vrf1 
ipv4 address 10.1.1.1 255.255.255.252 
ipv6 address 2001:db8:1111::2 ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe 
mpls enable 
router isis6 1 enable 
router isis6 1 circuit both 
no shutdown 
no log-link-change 
exit 
! 
interface ethernet2 
no to_rt2_ether2 
lldp enable 
vrf forwarding vrf1 
ipv4 address 10.1.4.1 255.255.255.252 
ipv6 address 2001:db8:1114::2 ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe 
mpls enable 
router isis6 1 enable 
router isis6 1 circuit both 
no shutdown 
no log-link-change 
exit 
! 
interface ethernet20001 
no description 
vrf forwarding host 
ipv4 address 10.255.255.254 255.255.255.0 
no shutdown 
no log-link-change 
exit 
! 
line tty1 
no login authentication 
exit 
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alias test bash command attach shell1 socat - exec:sh,ctty,pty,stderr 
alias test bash description 
alias test bash parameter optional 
! 
server telnet host 
security protocol telnet 
no login authentication 
vrf host 
exit 
! 
! 
end 

RTR2

hostname rtr2 
buggy 
! 
! 
vrf definition host 
exit 
! 
vrf definition vrf1 
rd 1:1 
exit 
! 
router isis4 1 
no vrf 
exit 
! 
router isis6 1 
vrf vrf1 
net-id 48.2222.0000.2222.00 
traffeng-id :: 
is-type both 
segrout 10 
level2 segrout 
level1 segrout 
redistribute connected 
exit 
! 


interface loopback0 
no description 
vrf forwarding vrf1 
ipv4 address 10.99.99.2 255.255.255.255 
ipv6 address 2001:db8:2222::1 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 
router isis6 1 enable 
router isis6 1 circuit both 
router isis6 1 segrout index 1 
router isis6 1 segrout node 
no shutdown 
no log-link-change 
exit 
! 
interface ethernet1 
description to_rtr3_ether2 
lldp enable 
vrf forwarding vrf1 
ipv4 address 10.1.3.2 255.255.255.252 
ipv6 address 2001:db8:1112::2 ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe 
mpls enable 
router isis6 1 enable 
router isis6 1 circuit both 
no shutdown 
no log-link-change 
exit 
! 
interface ethernet2 
no to_rt1_ether2 
lldp enable 
vrf forwarding vrf1 
ipv4 address 10.1.4.2 255.255.255.252 
ipv6 address 2001:db8:1114::3 ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe 
mpls enable 
router isis6 1 enable 
router isis6 1 circuit both 
no shutdown 
no log-link-change 
exit 


! 
interface ethernet20001 
no description 
vrf forwarding host 
ipv4 address 10.255.255.254 255.255.255.0 
no shutdown 
no log-link-change 
exit 
! 
line tty1 
no login authentication 
exit 
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alias test bash command attach shell1 socat - exec:sh,ctty,pty,stderr 
alias test bash description 
alias test bash parameter optional 
! 
server telnet host 
security protocol telnet 
no login authentication 
vrf host 
exit 
! 
! 
end 

RTR3

hostname rtr3 
buggy 
! 
! 
vrf definition host 
exit 
! 
vrf definition vrf1 
rd 1:1 
exit 
! 
router isis4 1 
vrf vrf1 
net-id 48.3333.0000.3333.00 
traffeng-id :: 
is-type both 
redistribute connected 
exit 
! 
router isis6 1 
vrf vrf1 
net-id 48.3333.0000.3333.00 
traffeng-id :: 
is-type both 
segrout 10 
level2 segrout 
level1 segrout 
redistribute connected 
exit 
! 
interface loopback0 
no description 
vrf forwarding vrf1 
ipv4 address 10.99.99.3 255.255.255.255 
ipv6 address 2001:db8:3333::1 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 
router isis6 1 enable 
router isis6 1 circuit both 
router isis6 1 segrout index 1 
router isis6 1 segrout node 
no shutdown 
no log-link-change 
exit 
! 
interface loopback1 
no description 
no shutdown 
no log-link-change 
exit 
! 
! 
interface ethernet1 
description to_rtr2_ether1 
lldp enable 
vrf forwarding vrf1 
ipv4 address 10.1.3.1 255.255.255.252 
ipv6 address 2001:db8:1112::3 ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe 
mpls enable 
router isis6 1 enable 
router isis6 1 circuit both 
no shutdown 
no log-link-change 
exit 
! 
interface ethernet2 
description to_rtr1_ether1 
lldp enable 
vrf forwarding vrf1 
ipv4 address 10.1.1.2 255.255.255.252 
ipv6 address 2001:db8:1111::3 ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe 
mpls enable 
router isis6 1 enable 
router isis6 1 circuit both 
no shutdown 
no log-link-change 
exit 
! 
interface ethernet20001 
no description 
vrf forwarding host 
ipv4 address 10.255.255.254 255.255.255.0 
no shutdown 
no log-link-change 
exit 
! 
line tty1 
no login authentication 
exit 
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alias test bash command attach shell1 socat - exec:sh,ctty,pty,stderr 
alias test bash description 
alias test bash parameter optional 
! 
server telnet host 
security protocol telnet 
no login authentication 
vrf host 
exit 
! 
! 
end 

Helpful show commands for this basic setup

 sh ipv4 route vrf1
 sh ipv6 route vrf1