Issue
In
this example we will configure xconnect between two PE routers (R2 and R5)
which are located in different ASs in order to achieve connectivity
Configuration
R1
R1#sh
run int s1/0
interface
Serial1/0
ip address 192.1.16.1 255.255.255.0
no keepalive
R2
R2#sh
run int s2/0
interface
Serial2/0
no ip address
no keepalive
R2#sh
run int f1/0
interface
FastEthernet1/0
ip address 192.1.23.2 255.255.255.0
speed 100
duplex full
mpls ip
R2#sh
run int lo0
interface
Loopback0
ip address 2.2.2.2 255.255.255.255
R2#sh
run | sec router ospf
router
ospf 1
router-id 2.2.2.2
network 2.2.2.2 0.0.0.0 area 0
network 192.1.23.2 0.0.0.0 area 0
R3
R3#sh
run int f2/0
interface
FastEthernet2/0
ip address 192.1.23.3 255.255.255.0
speed 100
duplex full
mpls ip
R3#sh
run int pos1/0
interface
POS1/0
ip address 192.1.34.3 255.255.255.0
encapsulation ppp
R3#sh
run | sec router ospf
router
ospf 1
router-id 3.3.3.3
redistribute bgp 100 subnets route-map MSSK
network 3.3.3.3 0.0.0.0 area 0
network 192.1.23.3 0.0.0.0 area 0
R3#sh
run | sec router bgp
router
bgp 100
bgp log-neighbor-changes
no bgp default ipv4-unicast
neighbor 192.1.34.4 remote-as 200
!
address-family ipv4
network 2.2.2.2 mask 255.255.255.255
network 3.3.3.3 mask 255.255.255.255
neighbor 192.1.34.4 activate
exit-address-family
R4
R4#sh
run int pos1/0
interface
POS1/0
ip address 192.1.34.4 255.255.255.0
encapsulation ppp
R4#sh
run int f2/0
interface
FastEthernet2/0
ip address 192.1.45.4 255.255.255.0
ip router isis 1
speed 100
duplex full
mpls ip
router
isis 1
net 49.0001.0000.0000.0004.00
is-type level-2-only
redistribute bgp 200 route-map MSSK
R4#sh
run | sec router bgp
router
bgp 200
bgp log-neighbor-changes
no bgp default ipv4-unicast
neighbor 192.1.34.3 remote-as 100
!
address-family ipv4
network 4.4.4.4 mask 255.255.255.255
network 5.5.5.5 mask 255.255.255.255
neighbor 192.1.34.3 activate
exit-address-family
R5
R5#sh
run int f1/0
interface
FastEthernet1/0
ip address 192.1.45.5 255.255.255.0
ip router isis 1
speed 100
duplex full
mpls ip
R5#sh
run int ser2/0
interface
Serial2/0
no ip address
no keepalive
serial restart-delay 0
xconnect 2.2.2.2 16 encapsulation mpls
R5#sh
run | sec router isis
ip router isis 1
ip router isis 1
router
isis 1
net 49.0001.0000.0000.0005.00
is-type level-2-only
R6
R6#sh
run int s1/0
interface
Serial1/0
ip address 192.1.16.6 255.255.255.0
no keepalive
serial restart-delay 0
Verification
Now,
R2 (the PE in AS 100) does not know about the loopback of R5 (and vice versa)
which will be used to configure the xconnect peering, and in order for MPLS to operate,
LDP has to assign labels, in order for that to take place we will redistribute
the routes in IGP (OSPF and ISIS in AS 100, 200 respectively) as IGP will
handle label assignments
R3#sh
run | sec ip pref
ip
prefix-list MSSK seq 5 permit 4.4.4.4/32
ip
prefix-list MSSK seq 10 permit 5.5.5.5/32
R4#sh
run | sec ip pref
ip
prefix-list MSSK seq 5 permit 2.2.2.2/32
ip
prefix-list MSSK seq 10 permit 3.3.3.3/32
route-map
MSSK permit 10
match ip address prefix-list MSSK
R3
router
ospf 1
redistribute
bgp 100 subnets route-map MSSK
R4
router
isis 1
redistribute
bgp 200 route-map MSSK
R2#show
mpls forwarding-table | inc 5.5.5.5
17 19 5.5.5.5/32 0 Fa1/0 192.1.23.3
R5#show
mpls forwarding-table | inc 2.2.2.2
17 18 2.2.2.2/32 0 Fa1/0 192.1.45.4
Now
in order for the labels to be passed through the ASes , we have to configure the
BGP neighbors to send the labels
R3
router
bgp 100
address-family
ipv4
neighbor 192.1.34.4 send-label
R4
router
bgp 200
address-family
ipv4
neighbor 192.1.34.3 send-label
Now
let us check the status of our L2VPN
R2#show
mpls l2transport vc 16
Local
intf Local circuit Dest address VC ID
Status
------------- -------------------------- ---------------
---------- ----------
Se2/0 HDLC 5.5.5.5 16 UP
R5#sh
mpls l2transport vc 16
Local
intf Local circuit Dest address VC ID
Status
------------- -------------------------- ---------------
---------- ----------
Se2/0 HDLC 2.2.2.2 16 UP
R1#ping
192.1.16.6
Type
escape sequence to abort.
Sending
5, 100-byte ICMP Echos to 192.1.16.6, timeout is 2 seconds:
!!!!!
Success
rate is 100 percent (5/5), round-trip min/avg/max = 20/20/24 ms
R6#ping
192.1.16.1
Type
escape sequence to abort.
Sending
5, 100-byte ICMP Echos to 192.1.16.1, timeout is 2 seconds:
!!!!!
Success
rate is 100 percent (5/5), round-trip min/avg/max = 20/21/24 ms
R1#traceroute
192.1.16.6 numeric
Type
escape sequence to abort.
Tracing
the route to 192.1.16.6
VRF
info: (vrf in name/id, vrf out name/id)
1 192.1.16.6 20 msec * 20 msec
R6#traceroute
192.1.16.1 numeric
Type
escape sequence to abort.
Tracing
the route to 192.1.16.1
VRF
info: (vrf in name/id, vrf out name/id)
1 192.1.16.1 20 msec * 20 msec
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