pseudowire headend

2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 1

Presented by Lim Fung HEROBU Technical Marketing

July 2013


CE S-PE P1

L2 PE, e.g. DSLAM

PW

Access Network

Global IP/MPLS Network

AC

L2 PE

AC

1. Customer edge (CE) node. This is typically a router but could be a host, DSLAM or Ethernet aggregation switch of some sort.

2. L2/PW feeder switch. The element may be a specialized, low-cost network node designed and optimized around Ethernet and PW functions. Most commonly it will be an aggregation node or an access node.

3. IOS-XR Service PE. This is where the PW termination onto a virtual interface and then attachment of the virtual interface to a L3 service instance is performed.


CPE S-PE P1

L2 PE, e.g. DSLAM

PW

Access Network

Global IP/MPLS Network

AC

PWs originate on L2/PW feeder nodes and terminated on an L3 service instance (VRF) at the S-PE

Cisco Confidential 2010 Cisco and/or its affiliates. All rights reserved. 4

EMSE ASR9K

Transport

Network

Residential

STB

Business

Corporate

Mobile 2G/3G / LTE

ASR9000 PE

L2/L3 VPN, BNG PW PW-HE*

ME3600 ME3800 ASR903 ASR901

IP/ MPLS Core VRF

BNG

VPLS/EVPN

1. Decoupling of service models from transport

2. Simplify transport models Unified MPLS 3. Sonet/SDH like OAM and resiliency with

MPLS-TP/MPLS-TE

4. Collapse Metro-PE and MSE

1. Leased transport or Multiple management domains

2. Multi-technology access/aggregation

3. SLA management 4. Capex optimizations

PW-HE any service anywhere

PW

-HE


PW

MPLS

CE PE PE

CE

xconnect xconnect

PW

MPLS

CE PE PE

xconnect xconnect

interface gig 0/0/0/1.1 l2transport

l2vpn

xconnect group vpws

p2p pwhe-red

interface gig 0/0/0/1.1

neighbor 100.100.100.100 pw-id 1

interface pw-ether 100 PWHE virtual interface

vrf vpn-red

ipv4 address 10.1.1.2/24

service-policy input pw_parent_in

service-policy output pw_parent_out

ipv4 access-group p-in-filter in

ipv4 access-group p-out-filter out

l2vpn

xconnect group pwhe

p2p pwhe-red

interface pw-ether 100

neighbor 100.100.100.100 pw-id 1

Regular VPWS

PWHE


PW

MPLS

CE PE PE

xconnect xconnect

PW

MPLS

CE

PE

xconnect

BD

PW


vrf vpn-red


l2vpn

xconnect group pwhe

p2p pwhe-red


neighbor 100.100.100.100 pw-id 1

interface bvi 100

vrf vpn-red


l2vpn

bridge group irb

bridge-domain irb

neighbor 100.100.100.100 pw-id 1

neighbor 100.100.100.100 pw-id 2

routed interface bvi 100

PWHE: p2p xconnect

IRB: multi-point bridging


Unified MPLS end-to-end transport architecture

Flexible service edge placement with virtual PWHE interface o L3 interface in phase 1 o L2 interface/sub-interface and L3 sub-interface in future o Feature parity as regular L3 interface (please refer the later slides for the gaps and roadmaps)

CE-PE routing is over MPLS transport network. It doesnt need direct L3 link any more

CE-PE virtual link is protected by the MPLS transport network

LDP Core / Internet Core

Access PE (A-PE)

Service PE (S-PE)

CE

Pseudowire

CE L3PE

Pseudowire

Internet Peering

Business L3 VPNs

Aggregation LDP domain

CE-PE L3 link over PW

L2 PW PWHE virtual interface

L2 (port or vlan)


Features are configured under pwhe virtual interface but they are applied on the physical interfaces

There is pwhe virtual interface to physical interface mapping

To assure QoS SLA, all traffic to/from a given pwhe interface must be mapped to a certain physical interface. So load balancing for pwhe must be per-PW basis, or per-VC load balancing

Per-VC load balancing is forced on the S-PE by the configuration

Per-VC load balancing must also be configured on the A-PE Router for ingress direction as well

Gig0/1/0/0

Pseudowire-foo

Pseudowire-foo

S-PE

Pseudowire-bar

Pseudowire-bar

Gig0/2/0/0

hash

PW-HE-foo

PW-HE-bar

Per-VC load balancing Features are applied to

physical interfaces


PW-HE (sub)interface is a virtual interface that is in theory global in scope and every LC has it replicated.

When features are applied on PW-HE, resources like uidb, statistics, TCAM, QOS would need to be applied on every LC/interface.

In order to overcome the scaling challenges pin-down interface list configuration has been chosen.

Both Tx and Rx of the PW-HE traffic is expected to be using the interfaces on the pin-down list


Generic interface list (aka pin down list) generic-interface-list atom interface TenGigE0/3/1/0

PWHE interface (VC type 4 and 5) interface PW-Ether1 ipv4 address 102.102.102.1 255.255.255.0 attach generic-interface-list atom

L2VPN l2vpn pw-class atom

encapsulation mpls xconnect group one

p2p vista interface PW-Ether1

neighbor 11.0.0.1 pw-id 1 pw-class atom


TX pindown For core to access case, PW TX traffic will only be sent to

one of the paths in interface list (based on VC-label hash)

Make sure the paths in the Interface-List are subset of the classic ECMP pathset chosen by IGPs for APE Loopback.

If classic IGP pathset and IF-list set are disjoint PW TX traffic will be dropped.

RX path steering / Pindown For access to core case, to make sure PW RX traffic arrives

only over IF-list, the routers in Access need to steer traffic towards these interface

To achieve this we need FLEX-LDP configured on S-PE Other MPLS traffic will use existing Loopback that is used as router-ID, as we know today.

Configure Static routes in access router (P/PE) directly connected to S-PE such that these new S-PE loopbacks are only reachable only over links in the IF-list. Redistribute these static routes into IGP config on these P/PE router that is directly connected to S-PE

Note: PW traffic arriving on Non-hosting LC will be dropped.

S-PE

Pseudowire foo

Pseudowire bar

Pseudowire bar

Pseudowire bar

Pseudowire foo

Gig0/1/0/0

Gig0/2/0/0

Gig0/1/0/1

Gig0/2/0/1


S-PE

Gig0/1/0/0

Gig0/2/0/0

Gig0/1/0/1

Gig0/2/0/1

Pseudowire foo

Pseudowire bar

Pseudowire bar

Pseudowire bar

Pseudowire foo

Configuration in IOS XR : generic-interface-list il1

interface gig0/1/0/0



generic-interface-list il2




vrf vpn-green




attach generic-interface-list il1


vrf vpn-blue




attach generic-interface-list il2

l2vpn

xconnect group pwhe

p2p pwhe-foo

interface pw-ether100

neighbor 100.100.100.100 pw-id 1

p2p pwhe2-bar

interface pw-ether200

neighbor 100.100.100.100 pw-id 2

Note: Up to 8 interfaces per interface list are supported Only physical links and bundles in interface-list. No tunnels or sub-interfaces.


For PW-HE to be up the PW has to be up

For PW to be up, the same conditions apply as for other PWs: attributes (CW, VC type, MTU) have to match, no fault indicated by PW status etc.

PW-HE forwarding also has to be up (this means at least one interface which can carry traffic), otherwise remote (A-PE) could black-hole

Note that if user mis-configures interface-list, e.g. by adding only link(s) which dont provide the reachability to A-PE, we might black-hole traffic (the PW-HE will be up since we dont detect mismatch between interface-list and forwarding)

Thank you.

pseudowire headend

Documents

bng pw pw

pw mpls ce pe pe ce

bd pw interface pwether

pw termination

pw functions

spe cisco confidential

cisco andor

ce spe p1 l2 pe