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AToM Tunnel Selection Using MPLS Traffic-Engineering

By default, AToM will use IGP to select what path that will used to send the pseudowire packets. In this scenario we will use MPLS Traffic-Engineering to select the pseudowire path.

Below is the diagram for our scenario:

We will build an AToM VC (Virtual Circuit) for CE-1 and CE-2 Ethernet connection. The VC will use Pseudowire Tunnel-Selection with MPLS Traffic-Engineering. We will select path (PE-1) – (P1) – (PE-2).

So, let we configure our routers (note that IGP and LDP is already configured and working properly).

Configure EoMPLS VC on PE-1 and PE-2

Configure RSVP for MPLS Traffic-Engineering support on the relevant interfaces at the Service Provider routers, that are PE-1 (F1/1,F0/0), PE-2 (F1/1, F0/0), P1 (F0/0, F1/0, F1/1) and P2 (F0/0, F1/0, F1/1):

mpls label protocol ldp
mpls traffic-eng tunnels
mpls ip
ip rsvp bandwidth 8000

The RSVP bandwidth for path (PE-1)-(P1)-(PE-2) is 80000, and for path (PE-1)-(P2)-(PE-2) is 70000 Mbps.

The configuration below is implemented only at router PE-1. Remember that MPLS Traffic-Engineering is for unidirectional traffic flow. So if we want to use Traffic-Engineering for the reserve flow, then we must implement it at router PE-2 too.

Configure IP Explicit-Path to use (PE-1)-(P1)-(PE-2) path:

ip explicit-path name P1-PE2 enable
next-address 10.0.0.2
next-address 10.1.1.1

Configure Interface Tunnel1 that used by EoMPLS VC 301 for preferred path. Don’t forget to apply the IP Explicit-Path P1-PE2 to this interface

interface Tunnel1
ip unnumbered Loopback0
no ip directed-broadcast
mpls traffic-eng tunnels
tunnel destination 10.10.10.3
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng priority 1 1
tunnel mpls traffic-eng bandwidth 7500
tunnel mpls traffic-eng path-option 1 explicit name P1-PE2
end

Configure pseudowire-class with MPLS encapsulation and using Tunnel1 as preferred-path:

pseudowire-class VIA_P1
encapsulation mpls
preferred-path interface Tunnel1

On router PE-1, configure subinterface that facing to the CE-1 (note that IP interface loopback0 on PE-2 is 10.10.10.3). In this scenario, we use VLAN 30 EoMPLS:

interface FastEthernet1/0.30
encapsulation dot1Q 30
no ip directed-broadcast
xconnect 10.10.10.3 301 pw-class VIA_P1
end

Because we just want to use Traffic-Engineering for one direction only (that is for flow from PE-1 to PE-2), then we configure the standard configuration for AToM application at the interface that facing to router CE-2 (note that IP interface loopback0 on PE-2 is 10.10.10.1):

interface FastEthernet1/0.30
encapsulation dot1Q 30
no ip directed-broadcast
xconnect 10.10.10.1 301 encapsulation mpls
end

Verifying EoMPLS VC on PE-1

So, let we verify our configuration:

PE-1#sh mpls l2 vc
Local intf Local circuit Dest address VC ID Status
————- ————————– ————— ———- ———-
Fa1/0.30 Eth VLAN 30 10.10.10.3 301 UP

PE-1#sh mpls l2 vc 301 det
Local interface: Fa1/0.30 up, line protocol up, Eth VLAN 30 up
Destination address: 10.10.10.3, VC ID: 301, VC status: up
Preferred path: Tunnel1, active
Default path: ready
Next hop: point2point
Output interface: Tu1, imposed label stack {39 33}
Create time: 00:42:44, last status change time: 00:40:36
Signaling protocol: LDP, peer 10.10.10.3:0 up
Targeted Hello: 10.10.10.1(LDP Id) -> 10.10.10.3
MPLS VC labels: local 34, remote 33
Group ID: local 0, remote 0
MTU: local 1500, remote 1500
Remote interface description:
Sequencing: receive disabled, send disabled
VC statistics:
packet totals: receive 0, send 0
byte totals: receive 0, send 0
packet drops: receive 0, seq error 0, send 0

Note that for VC 301, we will use Tunnel1 as a preferred-path.

PE-1#sh mpls traffic-eng tunnels Tunnel 1
Name: PE-1_t1 (Tunnel1) Destination: 10.10.10.3
Status:
Admin: up Oper: up Path: valid Signalling: connected
path option 1, type explicit P1-PE2 (Basis for Setup, path weight 2)
Config Parameters:
Bandwidth: 7500 kbps (Global) Priority: 1 1 Affinity: 0x0/0xFFFF
Metric Type: TE (default)
AutoRoute: disabled LockDown: disabled Loadshare: 7500 bw-based
auto-bw: disabled
Active Path Option Parameters:
State: explicit path option 1 is active
BandwidthOverride: disabled LockDown: disabled Verbatim: disabled
InLabel : –
OutLabel : FastEthernet1/1, 39
RSVP Signalling Info:
Src 10.10.10.1, Dst 10.10.10.3, Tun_Id 1, Tun_Instance 15
RSVP Path Info:
My Address: 10.0.0.1
Explicit Route: 10.0.0.2 10.1.1.2 10.1.1.1 10.10.10.3
Record Route: NONE
Tspec: ave rate=7500 kbits, burst=1000 bytes, peak rate=7500 kbits
RSVP Resv Info:
Record Route: NONE
Fspec: ave rate=7500 kbits, burst=1000 bytes, peak rate=7500 kbits
Shortest Unconstrained Path Info:
Path Weight: 2 (TE)
Explicit Route: 10.0.0.1 10.0.0.2 10.1.1.2 10.1.1.1 10.10.10.3
History:
Tunnel:
Time since created: 45 minutes, 36 seconds
Time since path change: 16 minutes, 35 seconds
Number of LSP IDs (Tun_Instances) used: 15
Current LSP:
Uptime: 16 minutes, 35 seconds
Prior LSP:
ID: path option 1 [14]
Removal Trigger: configuration changed
PE-1#

We can see that the path that used by interface Tunnel-1 is equivalent with our ip explicit-path configuration (P1-PE2).

The outgoing (outer) label that used by Tunnel1 is 39 via interface FastEthernet 1/1. We can see the corellation at router P1:

P1#sh mpls traffic-eng tunnels
LSP Tunnel PE-1_t1 is signalled, connection is up
InLabel : FastEthernet1/0, 39
OutLabel : FastEthernet1/1, implicit-null
RSVP Signalling Info:
Src 10.10.10.1, Dst 10.10.10.3, Tun_Id 1, Tun_Instance 15
RSVP Path Info:
My Address: 10.1.1.2
Explicit Route: 10.1.1.1 10.10.10.3
Record Route: NONE
Tspec: ave rate=7500 kbits, burst=1000 bytes, peak rate=7500 kbits
RSVP Resv Info:
Record Route: NONE
Fspec: ave rate=7500 kbits, burst=1000 bytes, peak rate=7500 kbits
P1#

And for the inner label (VC label), VC 301 use label 33. We can see this in the FIB table at router PE-2:

PE-2#sh mpls for
Local Outgoing Prefix Bytes tag Outgoing Next Hop
tag tag or VC or Tunnel Id switched interface
33 Untagged l2ckt(301) 0 none point2point
35 Pop tag 10.12.12.0/24 0 Fa0/0 10.3.3.2
Pop tag 10.12.12.0/24 0 Fa1/1 10.1.1.2
36 Pop tag 10.0.0.0/24 0 Fa1/1 10.1.1.2
37 Pop tag 10.2.2.0/24 0 Fa0/0 10.3.3.2
38 33 10.10.10.1/32 0 Fa1/1 10.1.1.2
42 10.10.10.1/32 0 Fa0/0 10.3.3.2
39 Pop tag 10.10.10.2/32 0 Fa1/1 10.1.1.2
64 Pop tag 10.10.10.4/32 0 Fa0/0 10.3.3.2

So, let we verify EoMPLS connectivity between CE-1 and CE-2:

CE-1#sh run int f1/0.30
interface FastEthernet1/0.30
encapsulation dot1Q 30
ip address 30.1.1.1 255.255.255.0
end
CE-1#ping 30.1.1.2
Sending 5, 100-byte ICMP Echos to 30.1.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 680/836/988 ms
CE-1#sh arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 30.1.1.2 0 cc05.1628.0010 ARPA FastEthernet1/0.30
Internet 30.1.1.1 – cc00.1628.0010 ARPA FastEthernet1/0.30
CE-1#

CE-2#sh run int f1/0.30
interface FastEthernet1/0.30
encapsulation dot1Q 30
ip address 30.1.1.2 255.255.255.0
end
CE-2#ping 30.1.1.1
Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 628/892/1580 ms
CE-2#sh arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 30.1.1.2 – cc05.1628.0010 ARPA FastEthernet1/0.30
Internet 30.1.1.1 2 cc00.1628.0010 ARPA FastEthernet1/0.30
CE-2#

Done …

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  1. Thai
    May 19, 2012 at 3:15 pm

    With GNS3 you can use that IOS
    pseudowire-class VIA_P1
    encapsulation mpls
    preferred-path interface Tunnel1

    I would go for that IOS
    thank you much

  1. July 28, 2008 at 12:01 pm
  2. July 28, 2008 at 10:40 pm

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