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Cisco Confidential © 2013 Cisco and/or its affiliates. All rights reserved. 1

Segment Routing Evoluce MPLS směrem k SDN

Josef Ungerman CSE, CCIE #6167

Oct 2013


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© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3

MPLS Segment Routing Overview

•  Emergence of Stateless MPLS •  Simplification – label distribution via IGP; no need for LDP and RSVP •  Scale – less state for routers to maintain to maintain •  Combined with SDN WAN Platform controller for path computation and programming •  Backward compatible with existing networks

A B C

M N O

Z

D

P

Nodal segment to Z (shortest path)

Nodal segment to Z

Adj Segment

Nodal segment : a shortest-path to the related node

Adjacency segment: one-hop through the related adjacency

Nodal segment to C

The state is no longer in the network, it’s in the packet.

draft-previdi-filsfils-isis-segment-routing draft-gredler-rtgwg-igp-label-advertisement


•  Simplicity –  less protocols to operate & troubleshoot –  no LDP sessions between routers –  deliver automated FRR for any topology

•  Scale –  avoid millions of labels in LDP database –  avoid millions of TE LSP’s in the network –  avoid millions of tunnels to configure

•  Simple to deploy and operate –  coexistence, incremental deployment –  MPLS: segment = label (push, pop, swap) –  Same behavior – ECMP, PHP, LFA…

X LFA <50ms (Loop-free alternate backup route+label)


•  Nodes advertises adjacency label per link –  simple IGP extension

•  Only advertising node installs adjacency segment in data plane

•  Enables source routing along any explicit path (segment list)

B C

N O

Z

D

P

A

9101

9105 9107

9103 9105

9101

9105

9107

9103

9105

9105

9107

9103

9105

9107

9103

9105

9103

9105 9105


•  Nodes advertise a node segment –  simple IGP extension

•  All remote nodes install node segment ids in data plane

A packet injected anywhere with top label 65 will reach Z

via IGP shortest path A B C

Z

D

65

FEC Z push 65

swap 65 to 65

swap 65 to 65 pop 65

Packet to Z

Packet to Z

65

Packet to Z

65

Packet to Z

65

Packet to Z


•  Source Routing

•  Any explicit path can be expressed: ABCOPZ

A B C

M N O

Z

D

P

Pop 9003

Packet to Z

65

9003

Packet to Z

65

Packet to Z

Packet to Z

65

Packet to Z

65

9003

72

Packet to Z

65

9003

72

72 72

65

65


•  IP-based FRR is guaranted in any topology

–  2002, LFA FRR project at Cisco –  draft-bryant-ipfrr-tunnels-03.txt

•  Directed LFA (DLFA) is guaranteed when metrics are symetric

•  No extra computation (RLFA)

•  Simple repair stack –  node segment to P node –  adjacency segment from P to Q

Backbone

C1 C2

E1 E4

E3 E2 1000

Node segment to P node

Default metric: 10


Non-Disjoint Traffic A sends traffic with [65] Classic ecmp “a la IP”

Disjoint Traffic A sends traffic with [111, 65] Packet gets attracted in blue plane and then uses classic ecmp “a la IP”

SR avoids state in the core

SR avoids enumerating RSVP-TE tunnels for each ECMP paths

ECMP-awareness!


•  Tokyo to Brussels –  data: via US: cheap capacity

–  VoIP: via Russia: low latency

•  CoS-based TE with SR –  IGP metric set such as

> Tokyo to Russia: via Russia

> Tokyo to Brussels: via US

> Russia to Brussels: via Europe

–  Anycast segment “Russia” advertised by Russia core routers

•  Tokyo CoS-based policy –  Data and Brussels: push the node segment to Brussels

–  VoIP and Brussels: push the anycast node to Russia, push Brussels

Node segment to Brussels

Node segment to Russia


•  At entry of the SR domain, two headers are pushed –  outer IPv6 header >  DA is within SRB block, active SID is within the DA

–  intermediate Routing Ext header with new type T (“the SR header” 43) >  I and E, Segment list and active pointer

•  Any node within SR domain is configured with SRB block (e.g. 0xCAFFE0123456789A/64)


Path ABCOPZ is ok. I account the BW. Then I steer the traffic on this path

FULL 66

65 68

Tunnel AZ onto {66, 68, 65}

The network is simple, highly programmable and responsive to rapid changes

2G from A to Z please


Towards an Open Network Environment for SDN Implementation Perspective: Evolve the Control- and Management Plane Architecture

•  Agility = simplicity + flexibility

•  ISIS/OSPF costs 0$, don’t fix what is no broken

•  Adding intelligence, and CPU power

Distributed Control Plane (selfish view of each node)

Evolved Control Plane Architecture (Examples)

…

Control/Network/Services-plane component(s) Data-plane component(s) Applications

Centralized Control (Master of Puppets?)

Adding Intelligence (what is the best for the network)

Traditional Control Plane Architecture


14

SDN WAN Collector Program

NB API

WAN Off-Net R1

R2

R3

Hi-Prio Cust App

1

2

3

4

①  Network conditions reported to collector, accessible to App

②  Congestion threshold triggers app to request Prem Cust to Prem Path Mapping

③  SDN WAN computes 1-7-2-3 SR path;

④  Programs: <SR stack via PCEP> < prem cust classifer via OF>

Premium

Normal Congested!!

R7

PCEP OF OF

4


Evolution of MPLS “MPLSDN”

G-MPLS

WAN Controller

DC

Cross Domain Orchestration

FlexLSP for transport orientated services

Baseline MPLS Architecture

DC Controller

Segment Routing

Segment Routing – simplified control plane; more scalable data plane

IP+Optical Multi-Layer Optimization (nLight)


Co tomu říkáte?

Klikněte na mapu šipkou z webexu J

Connect Club 10.října 2013

MPLS zhyne, bude nahraženo IPv6.

SDN je budoucnost. MPLS se musí přizpůsobit.

Jak vidíte budoucnost MPLS a SP páteří (5 let)?

MPLS pojede dál, jen k němu přibyde ta trocha SDN.

MPLS pojede dál v nezměněné podobě. SDN je jen výstřelek.


asr9000-pe1 ! router isis DEFAULT is-type level-2-only net 49.0000.1720.1625.5001.00 address-family ipv4 unicast metric-style wide ! interface Loopback0 passive address-family ipv4 unicast nodal-sid sid-value 16001 ! ! interface GigabitEthernet0/0/0/4 point-to-point address-family ipv4 unicast ! ! interface GigabitEthernet0/0/0/5 point-to-point address-family ipv4 unicast ! ! !

Packets with label 16001 forwarded

towards PE1 via IS-IS shortest path. PHP enabled by default.

172.16.255.101/32 SID=16101

PE2

P1

P2

PE1

172.16.255.102/32 SID=16102

172.16.255.2/32 SID=16002

172.16.255.1/32 SID=16001


asr9000-p2 ! router isis DEFAULT is-type level-2-only net 49.0000.1720.1625.5102.00 address-family ipv4 unicast metric-style wide ! interface Loopback0 passive address-family ipv4 unicast nodal-sid sid-value 16102 PHP-disable ! ! interface GigabitEthernet0/0/0/4 point-to-point address-family ipv4 unicast ! ! interface GigabitEthernet0/0/0/5 point-to-point address-family ipv4 unicast ! ! interface GigabitEthernet0/0/0/6 point-to-point address-family ipv4 unicast ! ! !

Packets with label 16102 forwarded

towards P2 via IS-IS shortest path. PHP

disabled.

172.16.255.101/32 SID=16101

PE2

P1

P2

PE1

172.16.255.102/32 SID=16102

172.16.255.2/32 SID=16002

172.16.255.1/32 SID=16001


172.16.255.101/32 SID=16101

PE2

P1

P2

PE1

172.16.255.102/32 SID=16102

172.16.255.2/32 SID=16002

172.16.255.1/32 SID=16001

RP/0/RSP0/CPU0:asr9000-pe1#sh isis database detail verbose asr9000-pe2.00 Tue May 7 12:49:07.939 PDT IS-IS DEFAULT (Level-2) Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL asr9000-pe2.00-00 0x0000076b 0xe36c 1123 0/0/0 Area Address: 49.0000 NLPID: 0xcc Hostname: asr9000-pe2 IP Address: 172.16.255.2 Metric: 10 IS-Extended asr9000-p2.00 Metric: 10 IS-Extended asr9000-p1.00 Metric: 10 IP-Extended 172.16.0.0/31 Metric: 10 IP-Extended 172.16.0.2/31 Metric: 0 IP-Extended 172.16.255.2/32 Nodal-SID: 16002 PHP-off:1 Ext:0 Total Level-2 LSP count: 1 Local Level-2 LSP count: 0 RP/0/RSP0/CPU0:asr9000-pe1#

Node segment id associated with PE2

loopback


RP/0/RSP0/CPU0:asr9000-pe1#sh isis database detail verbose asr9000-p2.00 Tue May 7 12:54:57.779 PDT IS-IS DEFAULT (Level-2) Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL asr9000-p2.00-00 0x0000001a 0x39d4 1169 0/0/0 Area Address: 49.0000 NLPID: 0xcc Hostname: asr9000-p2 IP Address: 172.16.255.102 Metric: 10 IS-Extended asr9000-pe2.00 Metric: 10 IS-Extended asr9000-pe1.00 Metric: 10 IS-Extended asr9000-p1.00 Metric: 10 IP-Extended 172.16.0.2/31 Metric: 10 IP-Extended 172.16.0.4/31 Metric: 10 IP-Extended 172.16.0.8/31 Metric: 0 IP-Extended 172.16.255.102/32 Nodal-SID: 16102 PHP-off:1 Ext:0 Total Level-2 LSP count: 1 Local Level-2 LSP count: 0 RP/0/RSP0/CPU0:asr9000-pe1#

172.16.255.101/32 SID=16101

PE2

P1

P2

PE1

172.16.255.102/32 SID=16102

172.16.255.2/32 SID=16002

172.16.255.1/32 SID=16001

Node segment id associated with P2

loopback


RP/0/RSP0/CPU0:asr9000-pe1#sh mpls forwarding Tue May 7 12:22:53.650 PDT Local Outgoing Prefix Outgoing Next Hop Bytes Label Label or ID Interface Switched ------ ----------- ------------------ ------------ --------------- ------------ 16001 Aggregate default: Per-VRF Aggr[V] \ default 59 16002 16002 No ID Gi0/0/0/4 172.16.0.4 18722 16002 No ID Gi0/0/0/5 172.16.0.7 0 16020 Aggregate RED: Per-VRF Aggr[V] \ RED 4500 16101 16101 No ID Gi0/0/0/5 172.16.0.7 0 16102 16102 No ID Gi0/0/0/4 172.16.0.4 0 RP/0/RSP0/CPU0:asr9000-pe1#

Local node segment id

Node segment id to reach PE1 via ECMP

Node segment id to reach P1


172.16.255.101/32 SID=16101

PE2

P1

P2

PE1

172.16.255.102/32 SID=16102

172.16.255.2/32 SID=16002

172.16.255.1/32 SID=16001


RP/0/RSP0/CPU0:asr9000-p2#sh mpls forwarding Tue May 7 13:17:35.480 PDT Local Outgoing Prefix Outgoing Next Hop Bytes Label Label or ID Interface Switched ------ ----------- ------------------ ------------ --------------- ------------ 16001 Pop No ID Gi0/0/0/4 172.16.0.5 0 16002 16002 No ID Gi0/0/0/6 172.16.0.2 21258 16101 16101 No ID Gi0/0/0/5 172.16.0.8 0 RP/0/RSP0/CPU0:asr9000-p2#

Node segment id to reach PE1 (PHP)


Node segment id to reach PE2

172.16.255.101/32 SID=16101

PE2

P1

P2

PE1

172.16.255.102/32 SID=16102

172.16.255.2/32 SID=16002

172.16.255.1/32 SID=16001


PE2 PE1 VRF RED

192.168.255.1/32 VRF RED

192.168.255.2/32 IP/MPLS

(segment routing)

hostname asr9000-pe1 ! vrf RED address-family ipv4 unicast import route-target 65172:0 ! export route-target 65172:0 ! ! ! interface Loopback11 vrf RED ipv4 address 192.168.255.1 255.255.255.255 ! router bgp 65172 address-family ipv4 unicast ! address-family vpnv4 unicast ! neighbor 172.16.255.2 remote-as 65172 update-source Loopback0 address-family ipv4 unicast ! address-family vpnv4 unicast ! ! vrf RED rd 65172:0 address-family ipv4 unicast redistribute connected ! ! !

L3VPN usual configuration

172.16.255.1/32 SID=16001

172.16.255.2/32 SID=16002


RP/0/RSP0/CPU0:asr9000-pe1#sh bgp vpnv4 unicast labels Tue May 7 13:21:11.106 PDT BGP router identifier 172.16.255.1, local AS number 65172 BGP generic scan interval 60 secs BGP table state: Active Table ID: 0x0 RD version: 1269798720 BGP main routing table version 23 BGP scan interval 60 secs Status codes: s suppressed, d damped, h history, * valid, > best i - internal, r RIB-failure, S stale, N Nexthop-discard Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Rcvd Label Local Label Route Distinguisher: 65172:0 (default for vrf RED) *> 192.168.255.1/32 0.0.0.0 nolabel 16020 *>i192.168.255.2/32 172.16.255.2 16000 nolabel Processed 2 prefixes, 2 paths RP/0/RSP0/CPU0:asr9000-pe1# RP/0/RSP0/CPU0:asr9000-pe1#sh cef vrf RED 192.168.255.2 Tue May 7 13:20:58.960 PDT 192.168.255.2/32, version 15, internal 0x14004001 (ptr 0xad279764) [1], 0x0 (0x0), 0x410 (0xadf7a4b0) Updated May 7 09:41:16.371 Prefix Len 32, traffic index 0, precedence n/a, priority 3 via 172.16.255.2, 3 dependencies, recursive [flags 0x6010] path-idx 0 [0xae0429a8 0x0] next hop VRF - 'default', table - 0xe0000000 next hop 172.16.255.2 via 16002/0/21 next hop 172.16.0.4/32 Gi0/0/0/4 labels imposed {16002 16000} next hop 172.16.0.7/32 Gi0/0/0/5 labels imposed {16002 16000} RP/0/RSP0/CPU0:asr9000-pe1#

Label stack to forward traffic to

192.168.255.2/32 (VRF RED) via

ECMP (as usual)

PE2 PE1 VRF RED

192.168.255.1/32 VRF RED

192.168.255.2/32 IP/MPLS

(segment routing)

172.16.255.1/32 SID=16001

172.16.255.2/32 SID=16002

BGP local/remote labels for VPNv4

prefixes (as usual)


•  External mailing list [email protected]

•  Segment Routing public material

http://www.slideshare.net/getyourbuildon/tagged/cisco_segment_routing •  Cisco internet draft (“Segment Routing with IS-IS Routing Protocol”)

http://tools.ietf.org/html/draft-previdi-filsfils-isis-segment-routing •  Google NANOG 57 presentation (“Topology Aware Blackbox Monitoring”)

http://www.nanog.org/meetings/abstract?id=2058

Thank you.

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