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MPLS ATOM Interworking – Ethernet and IP

Interworking is the capability of L2TPv3 to change encapsulations between CE devices. The transport on one CE device can be translated to another transport. An example of this would be Frame Relay to Ethernet over an MPLS cloud.

Key points:

Ethernet Interworking can be used with IP and non-IP protocols
IP Interworking can only be used with IP

Example of Frame Relay to Ethernet Interworking (Ethernet)

PE1:
mpls ldp router-id Loopback0
mpls label protocol ldp
pseudowire-class CU1-MPLS-PW
encapsulation mpls
interworking ethernet

interface FastEthernet1/0
description connection to CU1A f0/0
no ip address
no cdp enable
xconnect 192.168.1.2 101 pw-class CU1-MPLS-PW
!
CU1A:
interface FastEthernet0/0
ip address 172.16.11.1 255.255.255.252
!

interface Serial2/0
no ip address
encapsulation frame-relay
serial restart-delay 0
frame-relay intf-type dce
no clns route-cache
!
connect frame-ethernet Serial2/0 101 l2transport
xconnect 192.168.1.1 101 pw-class CU1-MPLS-PW

CU1B:
bridge irb
interface Serial2/0
no ip address
encapsulation frame-relay
serial restart-delay 0
no clns route-cache
!
interface Serial2/0.101 point-to-point
frame-relay interface-dlci 101
bridge-group 1
!
interface BVI1
ip address 172.16.11.2 255.255.255.252
no clns route-cache

bridge 1 protocol ieee
bridge 1 route ip
!

Some outputs for verification:
CU1B#o
Codes: C – connected, S – static, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route

Gateway of last resort is not set

172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.16.11.0/30 is directly connected, BVI1
O 172.16.1.1/32 [110/65] via 172.16.11.1, 00:07:19, BVI1
C 172.16.1.2/32 is directly connected, Loopback0
CU1B#ping 172.16.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/35/52 ms

CU1A#o
Codes: C – connected, S – static, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route

Gateway of last resort is not set

172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.16.11.0/30 is directly connected, FastEthernet0/0
C 172.16.1.1/32 is directly connected, Loopback0
O 172.16.1.2/32 [110/2] via 172.16.11.2, 00:07:35, FastEthernet0/0
CU1A#ping 172.16.1.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/35/84 ms

PE1#sho mpls forwarding-table
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
16 Pop Label 10.1.102.0/31 0 Fa0/0 10.10.110.0
17 17 10.1.230.0/31 0 Fa0/1 10.1.120.1
18 10.1.230.0/31 0 Fa0/0 10.10.110.0
19 Pop Label 10.20.30.0/31 0 Fa0/1 10.1.120.1
20 21 192.168.1.2/32 0 Fa0/0 10.10.110.0
21 Pop Label 192.168.1.10/32 0 Fa0/0 10.10.110.0
22 Pop Label 192.168.1.20/32 0 Fa0/1 10.1.120.1
23 23 192.168.1.30/32 0 Fa0/1 10.1.120.1
24 No Label l2ckt(101) 25728 none point2point

PE2#sho mpls forwarding-table
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
16 17 10.1.120.0/31 0 Fa0/0 10.1.102.0
17 10.1.120.0/31 0 Fa0/1 10.1.230.0
17 Pop Label 10.10.110.0/31 0 Fa0/0 10.1.102.0
19 Pop Label 10.20.30.0/31 0 Fa0/1 10.1.230.0
20 20 192.168.1.1/32 0 Fa0/0 10.1.102.0
21 Pop Label 192.168.1.10/32 0 Fa0/0 10.1.102.0
22 23 192.168.1.20/32 0 Fa0/1 10.1.230.0
23 Pop Label 192.168.1.30/32 0 Fa0/1 10.1.230.0
25 No Label l2ckt(101) 17461 none point2point

PE1#sho mpls l2transport vc 101

Local intf Local circuit Dest address VC ID Status
————- ——————– ————— ———- ———-
Fa1/0 Ethernet 192.168.1.2 101 UP

PE2#sho mpls l2transport vc 101

Local intf Local circuit Dest address VC ID Status
————- ——————– ————— ———- ———-
Se2/0 FR DLCI 101 192.168.1.1 101 UP

PE1#sho mpls l2transport vc 101 det
Local interface: Fa1/0 up, line protocol up, Ethernet up
Destination address: 192.168.1.2, VC ID: 101, VC status: up
Output interface: Fa0/0, imposed label stack {25 21}
Preferred path: not configured
Default path: active
Tunnel label: 21, next hop 10.10.110.0
Create time: 00:17:30, last status change time: 00:11:56
Signaling protocol: LDP, peer 192.168.1.2:0 up
MPLS VC labels: local 24, remote 25
Group ID: local 0, remote 0
MTU: local 1500, remote 1500
Remote interface description:
Sequencing: receive disabled, send disabled
VC statistics:
packet totals: receive 502, send 320
byte totals: receive 31550, send 39537
packet drops: receive 0, send 0

PE2#sho mpls l2transport vc 101 detail
Local interface: Se2/0 up, line protocol up, FR DLCI 101 up
MPLS VC type is Ethernet, interworking type is Ethernet
Destination address: 192.168.1.1, VC ID: 101, VC status: up
Output interface: Fa0/0, imposed label stack {24 20}
Preferred path: not configured
Default path: active
Tunnel label: 20, next hop 10.1.102.0
Create time: 00:11:46, last status change time: 00:11:44
Signaling protocol: LDP, peer 192.168.1.1:0 up
MPLS VC labels: local 25, remote 24
Group ID: local 0, remote 0
MTU: local 1500, remote 1500
Remote interface description: connection to CU1A f0/0
Sequencing: receive disabled, send disabled
VC statistics:
packet totals: receive 190, send 448
byte totals: receive 18876, send 39750
packet drops: receive 0, send 0

PE1#sho mpls l2transport binding
Destination Address: 192.168.1.2, VC ID: 101
Local Label: 24
Cbit: 1, VC Type: Ethernet, GroupID: 0
MTU: 1500, Interface Desc: connection to CU1A f0/0
VCCV Capabilities: None
Remote Label: 25
Cbit: 1, VC Type: Ethernet, GroupID: 0
MTU: 1500, Interface Desc: n/a
VCCV Capabilities: None

PE2#sho mpls l2transport bind
Destination Address: 192.168.1.1, VC ID: 101
Local Label: 25
Cbit: 1, VC Type: Ethernet, GroupID: 0
MTU: 1500, Interface Desc: n/a
VCCV Capabilities: None
Remote Label: 24
Cbit: 1, VC Type: Ethernet, GroupID: 0
MTU: 1500, Interface Desc: connection to CU1A f0/0
VCCV Capabilities: None

PE1#sho mpls l2transport hw-capability interface fastEthernet 0/0
Interface FastEthernet0/0

Transport type FR DLCI
Core functionality:
MPLS label disposition supported
Control word processing supported
Sequence number processing not supported
VCCV Type 1 processing supported
Edge functionality:
Not supported

Example of Frame Relay to Ethernet Interworking (IP)

PE1:
mpls ldp router-id Loopback0
mpls label protocol ldp
pseudowire-class CU1-MPLS-PW
encapsulation mpls
interworking ip
!
interface FastEthernet1/0
description connection to CU1A f0/0
no ip address
duplex auto
speed auto
no cdp enable
no clns route-cache
xconnect 192.168.1.2 101 pw-class CU1-MPLS-PW

PE2:
frame-relay switching
no mpls traffic-eng auto-bw timers frequency 0
mpls ldp router-id Loopback0
mpls label protocol ldp
pseudowire-class CU1-MPLS-PW
encapsulation mpls
interworking ip
!
interface Serial2/0
no ip address
encapsulation frame-relay
serial restart-delay 0
frame-relay intf-type dce
no clns route-cache
!
connect frame-ethernet Serial2/0 101 l2transport
xconnect 192.168.1.1 101 pw-class CU1-MPLS-PW

CU1A:
interface FastEthernet0/0
ip address 172.16.11.1 255.255.255.252
duplex auto
speed auto
no clns route-cache

CU1B:
interface Serial2/0
ip address 172.16.11.2 255.255.255.252
encapsulation frame-relay
ip ospf network broadcast ! note the need to ensure OSPF network types are compatible on both sides.
serial restart-delay 0
frame-relay map ip 172.16.11.1 101 broadcast
no clns route-cache
!
PE1#sho mpls l2transport vc 101 detail
Local interface: Fa1/0 up, line protocol up, Ethernet up
MPLS VC type is IP, interworking type is IP
Destination address: 192.168.1.2, VC ID: 101, VC status: up
Output interface: Fa0/0, imposed label stack {25 21}
Preferred path: not configured
Default path: active
Tunnel label: 21, next hop 10.10.110.0
Create time: 00:28:49, last status change time: 00:16:38
Signaling protocol: LDP, peer 192.168.1.2:0 up
MPLS VC labels: local 18, remote 25
Group ID: local 0, remote 0
MTU: local 1500, remote 1500
Remote interface description:
Sequencing: receive disabled, send disabled
VC statistics:
packet totals: receive 1963, send 977
byte totals: receive 121260, send 118233
packet drops: receive 0, send 0

PE2#sho mpls l2transport vc 101 detail
Local interface: Se2/0 up, line protocol up, FR DLCI 101 up
MPLS VC type is IP, interworking type is IP
Destination address: 192.168.1.1, VC ID: 101, VC status: up
Output interface: Fa0/0, imposed label stack {18 20}
Preferred path: not configured
Default path: active
Tunnel label: 20, next hop 10.1.102.0
Create time: 00:21:53, last status change time: 00:16:55
Signaling protocol: LDP, peer 192.168.1.1:0 up
MPLS VC labels: local 25, remote 18
Group ID: local 0, remote 0
MTU: local 1500, remote 1500
Remote interface description: connection to CU1A f0/0
Sequencing: receive disabled, send disabled
VC statistics:
packet totals: receive 119, send 81
byte totals: receive 9492, send 8786
packet drops: receive 0, send 0

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