Transcript Session MI.1 - PW/MPLS

Benchmarking Carrier Ethernet
Technologies Workshop
Session MI.1: PW/MPLS
Krakow, Poland
Lieven Levrau
30th April 2008
Agenda
1. Multi Segment Pseudo Wires
2. Multi-Segment Pseudo Wire OAM
3. Advanced Topics for MS-PW
2 | PW/MPLS | April 2008
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1
Service and Network Scale
Multi Segment Pseudo Wires
3 | PW/MPLS | April 2008
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Extending the MPLS Enabled Area
Diving L2VPN scalability requirements
PE3
PE2
CE
LSR
MPLS
CE
PE1
CE
MPLS
PE4
LSR
CE
MPLS Aggregation
Network
Full mesh of tunnels
and T-LDP sessions
MPLS
IP/MPLS
Backbone
LSR
PE5
PE6
Tunnels/Signalling
sessions grow exponentially
MPLS Aggregation
Networks
Scale VLL and VPLS services over a multi-area network or between providers
 Remove the need for a full mesh of Targeted LDP sessions between PEs
 Remove the need for a full mesh of RSVP-TE tunnels between PEs
 Minimise number of tunnels terminating on access/aggregation
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CE
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CE
CE
draft-ietf-pwe3-ms-pw-arch-02.txt
draft-ietf-pwe3-segmented-pw-04.txt
Multi-Segment PWs (PW switching)
FEC
FEC
FEC
FEC
FEC
FEC
T-PE
Multi-segment PW
S-PE
MPLS
CE
T-PE
CE
CE
S-PE
MPLS
T-PE
MPLS tunnel
CE
MPLS
Aggregation
Network
MPLS
Pseudo wire
segments
Terminating PE
Tunnels & PWs terminated
IP/MPLS
Backbone
Switching PE
Tunnels terminated
PWs switched between
ingress/egress tunnels
S-PE
T-PE
T-PE/S-PE
MPLS Aggregation Networks
FECs configured at S-PEs, label bindings advertised
PW cross connect configured at S-PEs
PWs switched between ingress/egress tunnels
• Simple PW label swap
• PW status messages mapped at each S-PE
• PW switching point TLV for loop detection
5 | PW/MPLS | April 2008
CE
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CE
CE
Multi-segment Pseudo-wire – How can you use them ?
Ethernet VLLs with SS-PW
SS-PW
MPLS tunnel
PE
CE
PE
T-LDP
CE
P
P
MPLS
MPLS
T-LDP
PE
PE
MPLS
CE
CE
T-LDP
MPLS
PE
PE
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CE
Multi-segment Pseudo-wire – How can you use them ?
Ethernet VLLs with MS-PW
MS-PW
T-PE
CE
T-PE
T-LDP
T-LDP
S-PE
MPLS
CE
S-PE
T-LDP
MPLS
T-PE
CE
T-PE
T-LDP
MPLS
T-LDP
CE
T-LDP
MPLS
T-LDP
S-PE
MPLS tunnel
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T-LDP
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T-PE
CE
2
Multi-Segment Pseudo Wire OAM
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OAM for PWs
PW have OAM capabilities to check / diagnose PW layer
 Connectivity testing:
 Virtual Circuit Connectivity Verification (VCCV)
– Uses a dedicated channel on a PW to test connectivity
 Defect notifications:
 Defect status mapped between AC and PW in the PE
– Interworking with ATM OAM & FR LMI
 PW status signalling propagates defect notifications along PW
MPLS
PE 1
FR AC
VCCV channel
CE 1
L2
I/F
PP
WW
LSP Tunnel
MPLS
PE 2
FR AC
MPLS PW L2
CE 2
I/F
(FR Network)
(FR Network)
FR PW
PW status
LMI full status
MS-PWs introduce two new requirements on OAM:
LMI full status
 Ability to test connectivity of segments of a PW, and to trace PW path
 Ability to generate defect notifications if a PW segment fails
9 | PW/MPLS | April 2008
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Multi-Segment Pseudo Wire OAM
Provide and coordinate OAM at the relevant levels in the MPLS network
 OAM Procedures for VPWS Interworking: draft-ietf-l2vpn-vpws-iw-oam PW OAM Message Mapping: draft-ietf-pwe3-oam-msg-mapProactive & reactive OAM mechanisms, independent at all levels
Service Level
e.g VRF-Ping, MAC-Ping
PW Level
e.g VCCV, PW status
Tunnel LSP Level
e.g MPLS OAM
draft-stokes-vkompella-l2vpn-hvpls-oam-00.txt
draft-ietf-pwe3-vccv-07.txt
draft-ietf-pwe3-control-protocol-17.txt
RFC4379
draft-ietf-bfd-mpls-02.txt
Multi-segment PWs require extensions to single segment PW OAM to allow:
 Segmented OAM (between 1 or more T/S-PEs)
 Propagation of defect notifications between PW segments & ingress/egress tunnels
10 | PW/MPLS | April 2008
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3
Advanced topics
Simplified Provisioning and Management of Advanced Service
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Emerging Requirements for MS-PW Provisioning
Maintain the same provisioning model as SS-PWs

“One-touch” provisioning for PWs
Remove the requirement to provision the S-PEs

Only provision the T-PEs
This has two new protocol implications:

Signalling must enable the full MS-PW to be established. This needs T-LDP to
be extended to multiple hops.

The S-PE path between the T-PEs is no longer determined by the MPLS tunnel.
This needs automatic PW path selection.
Proposed solutions are forward-looking and not yet implemented
12 | PW/MPLS | April 2008
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Extending T-LDP for Dynamic Multi-Segment PWs
draft-ietf-pwe3-dynamic-ms-pw-06.txt
Operational consistency with SS-PWs
 Reuse existing provisioning models
 Simple application to existing VPLS deployments
 Same OAM mechanisms
Implementation consistency with SS-PWs
 Existing PW implementations are LDP
 Minimal changes, mainly for addressing remote PEs
T-LDP addressing uses FEC 129 with AII type 2 from draft-ietf-pwe3-aii-aggregate0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
AII Type=02
|
Length
|
Global ID
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Global ID (contd.)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Prefix
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
AC ID
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
13 | PW/MPLS | April 2008
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Extending T-LDP for Dynamic Multi-Segment PWs
draft-ietf-pwe3-dynamic-ms-pw-06.txt
Support for QoS and TE for PWs
 Allows S-PEs to perform CAC
 Consistent traffic parameters, irrespective of PW type
 Translation done by layer 2 aware T-PE
 Allow asymmetric BW assignment to PWs
T-LDP extended with forward and reverse SENDER_TSPEC
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0|
PW BW
TLV
(0x096E)
|
TLV
Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Forward SENDER_TSPEC
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Reverse SENDER_TSPEC
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
14 | PW/MPLS | April 2008
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Committed rate bucket/size
Peak Rate
Minimum policed unit
Max packet size
Extending T-LDP for Dynamic Multi-Segment PWs
draft-ietf-pwe3-dynamic-ms-pw-06.txt
Fully qualified info in signalled
FEC allows T-PE/S-PE to
select next hop
T-LDP
CE
T-LDP
MPLS
T-PE
T-PE
T-LDP
CE
S-PE
MPLS
MS-PW
S-PE
CE
T-PE
MPLS tunnel
CE
CE
MPLS
FEC 129 provides
a unique key for the
Attachment circuit (AII)
IP/MPLS
Backbone
S-PE
T-PE
T-PE/S-PE
Global ID (e.g. AS#)
+ AC identifier
15 | PW/MPLS | April 2008
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CE
CE
Requirements for Routing PWs
Automatically select path for the MS-PW
 Not all routers are S-PEs, not all S-PEs are PW
switching or dynamic MS-PW signalling
capable
CE
 Cannot rely on IGP next hop
CE
 Must know connectivity state at PWE3 level
 In metro networks, assume all S-PEs in the
same AS, and are often MP-BGP incapable
domains anyway
 Routers may be small devices and support a
minimal routing implementation
CE
CE
 ...but we also need a solution for inter-AS
 Potentially a large number of small nodes
 Automated link state routing to avoid failed links /
determine which is the least cost path to reduce
provisioning overhead
 Support a combination of static and dynamically
learned routes
16 | PW/MPLS | April 2008
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Advertising PWE3 Reachability in BGP
draft-ietf-pwe3-dynamic-ms-pw-06.txt
Aggregated FECs advertised between BGP speaking S/T-PEs
Provides next-hop reachability through an S/T-PE
T-PE
T-LDP
T-LDP
CE
T-LDP
MPLS
T-PE
CE
S-PE
MPLS
MS-PW
S-PE
CE
T-PE
MPLS tunnel
CE
CE
MPLS
IP/MPLS
Backbone
S-PE
T-PE
T-PE/S-PE
17 | PW/MPLS | April 2008
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CE
CE
Advertising PWE3 Topology in IGP
draft-dolganow-pwe3-ospf-ext-.txt
OSPF is extensible via opaque link state advertisements (LSAs)
 These are already used for flooding traffic engineering information
 Can also be used to advertise aggregated PW AIIs within a single area
 Each S/T-PE can advertise its local topology using these LSAs
 Nodes that do not understand LSAs will simply flood them
Must not to disrupt or over burden the routing protocols that manage the infrastructure of a
service providers network
 Use aggregation of attachment identifiers
 Prioritisation of LSAs
AII TLV
PW Adjacency TLV
T-PEs
T-PEs
S-PE
S-PE
S-PE
S-PE
S-PE
S-PE
18 | PW/MPLS | April 2008
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Summary of Candidate PW Routing Solutions
IGP Extensions

IGP knows the state of the physical topology and potential PWE3 topology

OSPF and IS-IS extensible to allow PWE3 topology and ACs to be advertised using currently defined mechanisms

IGP is always present and is less costly to deploy:
 Does not require additional routing protocol or management layer
 Potentially simple to implement in basic PW CPEs
Multi-Protocol BGP (MP-BGP)

Allows reachability through a given S-PE to be advertised

Only provides PW next-hop information

Requires BGP to be deployed
 Although often used for MPLS based L3 services
Path Computation Element (PCE)

Enables best path through a domain to be calculated

Needs to learn underlying PWE3 topology

Requires PCE to be deployed
 Targeted at Inter-AS scenarios
IGP, BGP and PCE solutions are complementary
19 | PW/MPLS | April 2008
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 IP/MPLS is “the” technology to transport multi services
 Scalable
 Resilient
 Manageable
20 | PW/MPLS | April 2008
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www.alcatel-lucent.com
Thank you !
21 | PW/MPLS | April 2008
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