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Advances in BGP BRKRST-3371

Gunter Van de Velde

Sr. Technical Leader

© 2013 Cisco and/or its affiliates. All rights reserved. BRKRST-3371 Cisco Public

What is BGP?

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Without BGP the Internet would not exist in its current stable and simple form

It is the plumbing technology of the Internet

What a Google search “bgp abbreviation” finds?

– Source: http://www.all-acronyms.com/BGP Border Gateway Protocol Bacterial Growth Potential Battlegroup Becker, Green and Pearson <sensored entry> Bermuda grass pollen Berri Gas Plant beta-glycerophosphate biliary glycoprotein blood group bone gamma-carboxyglutamic acid protei… bone gamma-carboxyglutamic acid-contai… bone gla protein bone Gla-containing protein Borders Group, Inc. brain-type glycogen phosphorylase Bridge Gateway Protocol Broader Gateway Protocol Bureau de Gestion de Projet Brain Gain Program

http://www.all-acronyms.com/BGP/Border_Gateway_Protocol/4870

http://www.all-acronyms.com/BGP/Bacterial_Growth_Potential/851409

http://www.all-acronyms.com/BGP/Battlegroup/1129015

http://www.all-acronyms.com/BGP/Becker,_Green_and_Pearson/1003328

http://www.all-acronyms.com/BGP/Bermuda_grass_pollen/849470

http://www.all-acronyms.com/BGP/Berri_Gas_Plant/1223429

http://www.all-acronyms.com/BGP/beta-glycerophosphate/848267

http://www.all-acronyms.com/BGP/biliary_glycoprotein/846387

http://www.all-acronyms.com/BGP/blood_group/55208

http://www.all-acronyms.com/BGP/bone_gamma-carboxyglutamic_acid_protein/850178

http://www.all-acronyms.com/BGP/bone_gamma-carboxyglutamic_acid-containing_protein/847202

http://www.all-acronyms.com/BGP/bone_gla_protein/55209

http://www.all-acronyms.com/BGP/bone_Gla-containing_protein/850193

http://www.all-acronyms.com/BGP/Borders_Group,_Inc./42974

http://www.all-acronyms.com/BGP/brain-type_glycogen_phosphorylase/849876

http://www.all-acronyms.com/BGP/Bridge_Gateway_Protocol/1279817

http://www.all-acronyms.com/BGP/Broader_Gateway_Protocol/96403

http://www.all-acronyms.com/BGP/Bureau_de_Gestion_de_Projet/197282

http://www.all-acronyms.com/BGP/Brain_Gain_Program/1319634


Agenda

Motivation to Enhance BGP Scale and Performance Enhancements What happened in BGP Landscape? Some new Cool features that may interest you

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Agenda


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BGP started in 1989…

Motivation and Development of BGP: When the Internet grew and moved to an autonomous system (AS) mesh architecture it was needed to have stable, non-chatty and low CPU consuming protocol to connect all of these AS’s together. In June 1989, the first version of this

new routing protocol was formalized, with the publishing of RFC 1105, A Border Gateway Protocol (BGP).

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Service Provider Routing and Services progress

Multimedia, Mobile Internet and Cloud Services will generate massive bandwidth explosion Prefix growth is almost a linear curve Evolution of offered BGP services go from basic technologies to very advanced infrastructures

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Control-plane Evolution Most of services are progressing towards BGP

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Service/transport Before 2008 2013 and future

IDR (Peering) BGP BGP (IPv6)

SP L3VPN BGP BGP + FRR + Scalability

SP Multicast VPN PIM BGP Multicast VPN

DDOS mitigation CLI BGP flowspec

Network Monitoring SNMP BGP monitoring protocol

Security Filters BGP Sec (RPKI), DDoS Mitigation

Proximity BGP connected app API

SP-L3VPN-DC BGP Inter-AS, VPN4DC

Business & CE L2VPN LDP BGP PW Sign (VPLS)

DC Interconnect L2VPN BGP MAC Sign (EVPN)

MPLS transport LDP BGP+Label (Unified MPLS)

Data Center OSPF/ISIS BGP + Multipath

Massive Scale DMVPN NHRP / EIGRP BGP + Path Diversity

Campus/Ent L3VPN BGP (IOS) BGP (NX-OS)


Why BGP is so successful ?

Robustness: Run over TCP Low Overhead protocol: sends an update once and then remains silent Scalability: Path Vector Protocol, allows full mesh High Availability: NSR, PIC,… Well Known : Tons of engineers know BGP Simplicity: BGP is simple (even if knobs make BGP BIG and sometimes less trivial to read) Multi-protocol: IPv4, IPv6, L2VPN, L3VPN, Multicast Incremental: easy to extend: NLRI,Path Attribute, Community Flexible: Policy

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Scale & Performance Enhancements

Update Generation Enhancements – Update generation is the most important, time-critical task – Is now a separate process, to provide more CPU Quantum

Parallel Route Refresh – Significant delay (up to 15-30 minutes) seen in advertising incremental updates while RR is servicing route refresh requests or

converging newly established peers – Refresh and incremental updates run in parrallel

Keepalive Enhancements – Loosing or delayed keep-alive message result in session flaps – Hence keep-alive processing is now placed into a separate process using priority queuing mechanism

Adaptive Update Cache Size – Instead of using a fixed cache size, the new code dynamically adapts to the address family used, the available router memory

and the number of peers in an update group

BGP Scaling

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Agenda


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Scale & Performance Enhancements

PE Scaling –PE-CE Optimization In old code slow convergence was experienced with large numbers of CE’s Improved by intelligently evaluating VPN prefixes based upon the prefixes in the CE’s VRF –VRF-Based Advertise Bits Increased memory consumption when number of VRF’s was scaled on a PE Smart reuse of advertise bit space for VRF

Route Reflector Scaling –Selective RIB Download A Route-Reflector needs to receive the full RIB, however not all prefixes MUST be in the Forwarding Information Base (FIB) So, we now allow by using user policy to only download selected prefixes in the FIB

More about BGP Performance tuning in BRKRST-3321

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BGP Resiliency/HA Enhancement

Issue: Slow peers in update groups block convergence of other update group members by filling message queues/transmitting slowly

Persistent network issue affecting all BGP routers

Two components to solution Detection Protection

Detection BGP update timestamps Peer’s TCP connection characteristics

Slow Peer Management

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Protection Move slower peers out of update group Separate slow update group with matching policies created Any slow members are moved to slow update group Detection can be automatic or manual with CLI command

Automatic recovery Slow peers are periodically checked for recovery Recovered peers rejoin the main update group

Isolation of slow peers unblocks faster peers and lets them converge as fast as possible

Slow Peer Management

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ASR1000 RP2, RP1, ASR1001 and 7200 BGP Route and Session Scalability Comparison - RR

• Tested with BGP selective download feature for ipv4/ipv6 for dedicated RR application. This feature prevents ipv4/ipv6 BGP routes to be installed in RIB and FIB. It reduces memory usage per ipv4/ipv6 prefix and CPU utilization

• ASR 1000 with RP1 allocates ~1.7GB to IOSd, ASR 1001 with 4GB allocates ~1.4GB to IOSd, whereas on NPE-G2 entire 2G is used by IOS

7200 NPE-G2 (2GB)

ASR1000 RP1 (4GB)

ASR1001 (4GB)

ASR1001 (8GB)

ASR1001 (16GB)

ASR1000 RP2 (8GB)

ASR1000 RP2 (16GB)

ipv4 routes 4M 7M* 2M* 9M* 17M* 12M* 29M*

vpnv4 routes 7M 6M 2M 8M 16M 10M 24M

ipv6 routes 2M 5M* 2M* 8M* 15M* 9M* 24M*

vpnv6 routes 6M 5M 1.5M 7.5M 14.5M 9M 21M

BGP sessions <1000 4000 4000 4000 4000 8000 8000

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ASR 1000 RP1 and RP2 Convergence Performance Comparison - RR

Tested with peer groups (1K RR clients per peer group) 7200 NPE-G2 can not converge in the above test cases. ASR1000 RP2 converges about twice faster than 7200 NPE-G2 based on RR customer profile testing CPU utilization below 5% after convergence Link to Isocore report http://www.cisco.com/en/US/prod/collateral/routers/ps9343/ITD13029-ASR1000-RP2Validationv1_1.pdf

Tested with 1M Total Unique Routes

Total Routes Reflected by RR to All Clients (Number of routes x Number of Clients)

ASR1000 RP1 (4GB) Convergence (in seconds)

ASR1001 (16GB) Convergence (in seconds)

ASR1000 RP2 (16GB) Convergence (in seconds)

ipv4 (1K RR clients) 1Billion 220 133 75

vpnv4 (1K RR clients, 8K RT) 1Billion 680 489 221

ipv6 (1K RR clients) 1Billion 720 393 194

vpnv6 (1K RR clients, 8K RT) 1Billion 877 811 293

ipv4 (2K RR clients) 2 Billion 375 270 138

vpnv4 (2K RR clients, 8K RT) 2 Billion 1285 797 394

ipv6 (2K RR clients) 2 Billion 1126 897 284

vpnv6 (2K RR clients, 8K RT) 2 Billion 1766 1691 551

for your reference

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http://www.cisco.com/en/US/prod/collateral/routers/ps9343/ITD13029-ASR1000-RP2Validationv1_1.pdf


Agenda


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What Happened in XR Landscape?

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4.0 4.1 4.1.1 4.2 4.2.1 4.2.3 4.2.4 4.3.0 4.3.1

• Add Path Support • Accumulated

Interior Gateway Protocol (AIGP) Metric Attribute

• Unipath PIC for non-VPN address-families (6PE/IPv6/IPv4 Unicast)

• RT-Constraint

• BGP Accept Own

• Multi-Instance/Multi-AS

• BGP 3107 PIC Update for Global Prefixes

• Prefix Origin Validation based on RPKI

• PIC for RIB and FIB

• Attribute Filtering and Error handling

• DMZ Link Bandwidth for Unequal Cost Recursive Load Balancing

• Selective VRF Download • 6PE/6vPE over L2TPv3 • Next-Generation

Multicast VPN

• BGP Based DDoS Mitigation


What Happened in IOS Landscape?

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15.2(1)S 15.2(2)S 15.2(4)S 15.3(1)S 15.3(2)S

Origin AS Validation

Gracefull Shutdown iBGP NSR mVPN BGP SAFI 129 NSR without Route-Refresh

Additional Path Attribute Filtering and Error Handling Diverse Path Graceful Shutdown IPv6 client for Single hop BFD IPv6 PIC Core and Edge RT Constraint IP Prefix export from a VRF into global Table

mVPNv6 Extranet Support

Local-AS allow-policy RT/VPN-ID Attribute Rewrite Wildcard VRF Aware Conditional Announcement


What Happened in XE Landscape?

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3.8 3.9

Multicast VPN BGP Dampening Multiple Cluster IDs VPN Distinguisher Attribute

IPv6 NSR Local-AS Allow-policy RT or VPN-ID Rewrite Wildcard VRF Aware Conditional Advertisement


What Happened NXOS Landscape?

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5.2 6.0 6.1 6.2

Default information originate support Flexible distance manipulation with Inject map Unsupress map as-format command for AS-plain & AS-dot Enhancements for removal of private AS enable route target import-export in default VRF InterAS option B-lite BGP Authentication for Prefix-based neighbors

BGP AddPath BGP send community both BGP Neighbor AF weight command

BGP med confed and AS multipath-relax BGP next hop self for route reflector

Prefix Independent Convergence (Core) local-as AS Override (allowas-in) Disable 4-byte AS advertisement MP BGP – MPLS VPNs, 6PE, MDT


Agenda


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PIC Edge Feature Overview

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Internet Service Providers provide strict SLAs to their Financial and Business VPN customers where they need to offer a sub-second convergence in the case of Core/Edge Link or node failures in their network

Prefix Independent Convergence (PIC) has been supported in IOS-XR/IOS for a while for CORE link failures as well as edge node failures

BGP Best-External project provides support for advertisement of Best-External path to the iBGP/RR peers when a locally selected bestpath is from an internal peer

BGP PIC Unipath provides a capability to install a backup path into the forwarding table to provide prefix independent convergence in case of the PE-CE link failure


10.1.1.0/24 VPN1 Site #1

MPLS Cloud Traffic Flow 10.2.2.0/24

VPN1 Site #2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR

PIC Edge: PE-CE Link Protection

PE3 configured as primary, PE4 as backup –PE3 preferred over PE4 by local preference –CE2 has different RDs in VRFs on PE3 and PE4 –PE4: advertise-best-external, to advertise route via PE4-CE2 link –PE3: additional-paths install, to install primary and backup path


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10.1.1.0/24 VPN1 Site #1


VPN1 Site #2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR

PIC Edge: Link Protection

PE3 has primary and backup path – Primary via directly connected PE3-CE2 link – Backup via PE4 best external route

What happens when PE3-CE2 link fails?


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10.1.1.0/24 VPN1 Site #1


VPN1 Site #2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR


CEF (via BFD or link layer mechanism) detects PE3-CE2 link failure – CEF immediately swaps to repair path label

Traffic shunted to PE4 and across PE4-CE2 link


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10.1.1.0/24 VPN1 Site #1

MPLS Cloud

Traffic Flow

10.2.2.0/24 VPN1 Site

#2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR

Withdraw route via PE3


PE3 withdraws route via PE3-CE2 link – Update propagated to remote PE routers


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10.1.1.0/24 VPN1 Site #1

MPLS Cloud

Traffic Flow

10.2.2.0/24 VPN1 Site

#2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR

Withdraw route via PE3


BGP on remote PEs selects new bestpath – New bestpath is via PE4 – Traffic flows directly to PE4 instead of via PE3


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10.1.1.0/24 VPN1 Site #1


VPN1 Site #2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR

PIC Edge: Edge Node Protection

PE3 configured as primary, PE4 as backup – PE3 preferred over PE4 by local preference – CE2 has different RDs in VRFs on PE3 and PE4 – PE4: advertise-best-external, to advertise route via PE4-CE2 link – PE1: additional-paths install, to install primary and backup path


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10.1.1.0/24 VPN1 Site #1

MPLS Cloud

Traffic Flow

10.2.2.0/24 VPN1 Site

#2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR


PE1 has primary and backup path – Primary via PE3 – Backup via PE4 best external route

What happens when node PE3 fails?


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10.1.1.0/24 VPN1 Site #1

MPLS Cloud

Traffic Flow

10.2.2.0/24 VPN1 Site

#2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR

PE3’s /32 host route

removed from IGP




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10.1.1.0/24 VPN1 Site #1

MPLS Cloud

Traffic Flow

10.2.2.0/24 VPN1 Site

#2

PE1

PE2

PE3

PE4

CE1 CE2

Primary

Backup

RR

PE3’s /32 host route

removed from IGP


PE1 detects loss of PE3’s /32 host route in IGP – CEF immediately swaps forwarding destination label from

PE3 to PE4 using backup path

BGP on PE1 computes a new bestpath later, choosing PE4


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Enabling BGP PIC – Enabling IP Routing Fast Convergence

BGP PIC leverages IGP convergence Make sure IGP converges quickly IOS-XR: IGP Timers pretty-much tuned by default IOS: Sample OSPF config:

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process-max-time 50 ip routing protocol purge interface interface … carrier-delay msec 0 negotiation auto ip ospf network point-to-point bfd interval 100 min_rx 100 mul 3 router ospf 1 ispf timers throttle spf 50 100 5000 timers throttle lsa all 0 20 1000 timers lsa arrival 20 timers pacing flood 15 passive-interface Loopback 0 bfd all-interfaces

for your reference


Enabling BGP PIC Edge: IOS-XR

Two BGP-PIC Edge Flavors: BGP PIC Edge Multipath and Unipath Multipath: Re-routing router load-balances across multiple next-hops, backup next-hops

are actively taking traffic, are active in the routing/forwarding plane, commonly found in active/active redundancy scenarios. – No configuration, apart from enabling BGP multipath (maximum-paths ... )

Unipath: Backup path(s) are NOT taking traffic, as found in active/standby scenarios

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route-policy backup ! Currently, only a single backup path is supported set path-selection backup 1 install [multipath-protect] [advertise] end-policy

router bgp ... address-family ipv4 unicast additional-paths selection route-policy backup ! address-family vpnv4 unicast additional-paths selection route-policy backup !

for your reference


Enabling BGP PIC Edge: IOS

As in IOS-XR, PIC-Edge w/ multipath requires no additional configuration PIC-Edge unipath needs to be enabled explicitly ...

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router bgp ... address-family ipv4 [vrf ...] or address-family vpnv4

bgp additional-paths install

http://www.cisco.com/en/US/docs/ios/iproute_bgp/configuration/guide/irg_bgp_mp_pic.html

http://www.cisco.com/en/US/docs/ios/ios_xe/iproute_bgp/configuration/guide/irg_best_external_xe.html

... or implicitly when enabling best external

router bgp ... address-family ipv4 [vrf ...] or address-family vpnv4

bgp advertise-best-external

for your reference


Question: How will my PE’s learn about the alternate Paths?

By default my RR Only-Reflects the Best-Route

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RR

PE2

PE3

Z NH:PE3, P:Z

NH:PE2, P:Z

PE1

Prefix Z Via PE2

E0

E0

Prefix Z Via E0

Prefix Z Via E0

NH:PE2, P:Z


Diverse BGP Path Distribution Shadow Session

Easy deployment – no upgrade of any existing router is required, just new iBGP session per each extra path (CLI knob in RR1) Diverse iBGP session does announce the 2nd best path

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RR1 NH:PE2, P:Z

NH:PE2, P:Z Prefix Z Via PE2 Via PE3 NH:PE3, P:Z

NH:PE3, P:Z

PE2

PE3

Z PE1


BGP Add-Path

Add-Path will signal diverse paths from 2 to X paths Required all Add-Path receiver BGP router to support Add-Path capability.

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RR1 NH:PE2, P:Z AP 1 NH:PE2, P:Z

Prefix Z Via PE2 Via PE3 NH:PE3, P:Z AP 2

NH:PE3, P:Z

PE2

PE3

Z PE1


BGP Add-path flavors

IETF defines 5 flavors of Add-x-Path. 2 are implemented by Cisco: Add-n-path: with add-n-path the route reflector will do best path computation for all paths and

send n best to BR/PE. – Usecase: Primary + n-1 Backup scenario. (n is maximal for IOS-XR 2 and 3 for IOS).

Add-all-path: with add-all-path, the route reflector will do the primary best path computation (only on first path) and then send all path to BR/PE. – Usecase: Large DC ECMP load balancing, hot potato routing scenario

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Add-path: selecting second best

1. Select best 2. Remove all paths whose next-hop == best’s (including best) 3. Run bestpath selection again on the remaining paths to select backup

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Simple rule


Add-Path Configuration – IOS-XR

Enable in global address-family mode – Enables for all IBGP neighbors Enable/Disable in neighbor mode

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router bgp 100 address-family ipv4 unicast additional-paths send ! address-family vpnv4 unicast additional-paths send ! neighbor 1.1.1.1 remote-as 100 address-family ipv4 unicast ! address-family vpnv4 unicast ! ! neighbor 2.2.2.2 remote-as 100 capability additional-paths send disable address-family ipv4 unicast !

for your reference


Add-Path Configuration – IOS-XR

Enable in global address-family mode – Enables for all IBGP neighbors Enable/Disable in neighbor mode

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router bgp 100 address-family ipv4 unicast additional-paths receive ! address-family vpnv4 unicast additional-paths receive ! neighbor 1.1.1.1 remote-as 100 address-family ipv4 unicast ! address-family vpnv4 unicast ! ! neighbor 2.2.2.2 remote-as 100 capability additional-paths receive disable address-family ipv4 unicast ! ! !

for your reference


PIC Edge: Test Results

Test Setup Node Failure Link Failure

No PIC Edge, No BFD 12-14 sec 8-17 sec

BFD Only 10-12 sec 6-12 sec

PIC Edge Only 8 sec 4 sec

PIC Edge, BFD 0 sec 0 sec


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Automated Route Target Filtering

Increased VPN service deployment increases load on VPN routers –10% YOY VPN table growth –Highly desirable to filter unwanted VPN routes

Multiple filtering approaches –New RT filter address family –Extended community ORF

BGP Feature

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Derive RT filtering information from VPN RT import lists automatically

Exchange filtering info via RT filter AF or extended community ORF

Translate filter info received from neighbors into outbound filtering policies

Generate incremental updates for received RT update queries

Incremental deployment possible/desirable

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BGP Feature


PE-1

PE-2

PE-3

PE-4

RR-1 RR-2

VRF- Blue

VRF- Red

VRF- Red

VRF- Green

RT-Constraint: NLRI= {VRF-Blue, VRF-Red}

RT-Constraint: NLRI= {VRF-Green, VRF-Purple}

RT-Constraint: NLRI= {VRF-Purple, VRF-Blue}

RT-Constraint: NLRI= {VRF-Red, VRF-Green}

RT-Constraint: NLRI= {VRF-Blue, VRF-Red, VRF-Green}

RT-Constraint: NLRI={VRF-Green, VRF-Purple, VRF-Blue}

VRF- Green

VRF- Purple

VRF- Purple

VRF- Blue


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Improves PE and RR scaling and performance by sending only relevant VPN routes


IOS XR - Accept own

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Accept own

This feature allows movement from a PE-Based service provisioning model to a centralized router reflector (RR)-based service provisioning model. With this feature, you can define route TO service-VRF mapping within a centralized route reflector and then propagate this information down to all the PE clients of that RR. Without this feature, you would define the route TO service VRF mapping in all PE devices, thereby incurring a high configuration overhead, which could result in more errors.

This feature enables a route reflector to modify the Route Target (RT) list of a VPN route that is distributed by the route reflector, enabling the route reflector to control how a route originated within one VRF is imported into other VRFs.

router#configure router(config)#router bgp 100 router(config-bgp)#neighbor 10.2.3.4 router(config-bgp-nbr)#address-family vpnv4 unicast router(config-bgp-nbr-af)#accept-own


AIGP (Accumulated IGP Metric Attribute for BGP) http://tools.ietf.org/html/draft-ietf-idr-aigp-09 Optional, non-transitive BGP path attribute BGP attribute to provide BGP a way to make its routing decision based on

the IGP metric, to choose the “shortest” path between two nodes across different AS.

The main driving force for this feature is to solve the IGP scale issue seen in some ISP core network.

Mainly to be deployed to carry nexthop prefixes/labels across different AS within the same administrative domain.

The remote ingress PE select its best path using the modified best path selection process using AIGP metric.

Overview – AIGP

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Overview – AIGP

Passing AIGP attribute to non-AIGP capable neighbors • Translate AIGP into cost-community • 2 POI of pre-best-path and igp-cost are supported • A transitive keyword to make cost-comm transitive to eBGP neighbors • Redistribute BGP (with AIGP) into IGP – • Translate AIGP value into BGP MED

Other software components • Route installation – for BGP to tag AIGP metric during route installation • NH notification – when AIGP metric changed

– Update generation throttling is not supported in 4.0 – It is highly recommended to deploy BGP best-external and Additional-path in conjunction with

the AIGP attribute, to effectively achieve the desired routing policy.

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AIGP: Originating AIGP

router bgp 1 address-family ipv4 unicast redistribute ospf 1 route-policy set_aigp_1

route-policy set_aigp_1 if destination in (61.1.1.0/24 le 32) then set aigp-metric 111 elseif destination in (2100::1:0/112, 2100::2:0/112) then set aigp-metric igp-cost Endif end-policy

AIGP is enabled between iBGP neighbors by default AIGP between eBGP neighbors need to be enabled AIGP can be originated by using redistribute ospf, redistribute isis, redistribute static or the BGP network command. AIGP can also be originated using neighbor address-family inbound or outbound policy to set AIGP to be the IGP cost or to a fixed value.

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What is Multi-Instance BGP?

60

A new IOS-XR BGP architecture to support multiple instances along the lines of OSPF instances

Each BGP instance is a separate process running on the same or a different RP/DRP node

The BGP instances do not share any prefix table between them

No need for a common adj-rib-in (bRIB) as is the case with distributed BGP

The BGP instances do not communicate with each other and do not set up peering with each other

Each individual instance can set up peering with another router independently


What is Multi-AS BGP?

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It will be possible to configure each instance of a multi-instances BGP with a different AS number

Global address families can’t be configured under more than one AS except vpnv4 and vpnv6

VPN address-families may be configured under multiple AS instances that do not share any VRFs


Configuration Example for your reference

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Attribute Filtering and error-handling

Attribute filtering – Unwanted optional transitive attribute such as ATTR_SET, CONFED segment in

AS4_PATH causing outage in some equipments. – Prevent unwanted/unknown BGP attributes from hitting legacy equipment Block specific attributes Block a range of non-mandatory attributes

Error-handling – draft-ietf-idr-optional-transitive-04.txt – Punishment should not exceed the crime – Gracefully fix or ignore non-severe errors – Avoid session resets for most cases – Never discard update error, as that can lead to inconsistencies

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Architecture

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Invalid Attribute Contents

Wrong Attribute Length Unknown Attributes Unwanted Attributes

Malformed BGP Updates Transitive Attributes

Attribute Filtering

Error-handling

NLRI processing…


Attribute filtering

First level of inbound filtering Filtering is configured as a range of attribute codes and a corresponding action

to take (Note: Never Discard Update as that can lead towards inconsistencies) Actions

– Discard the attribute – Treat-as-withdraw Applied when parsing each attribute in the received Update message

– When a attribute matches the filter, further processing of the attribute is stopped and the corresponding action is taken

68

for your reference


Error-handling

Comes into play after attribute-filtering is applied When we detect one or more malformed attributes or NLRIs or other fields in

the Update message Steps

– Classification of errors – Actions to be taken – Logging

69

for your reference


Origin Validation for E-BGP routes Next release to cover origin validation for locally sourced routes Support client functionality of RPKI RTR protocol

Separate database to store record entries from the cache Support to announce path validation state to IBGP neighbors using a well

known path validation state extended community Modified route policies to incorporate path validation states

BGP Origin Validation

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Prefix hijacking

Announce someone else’s prefix Announce a more specific of someone else’s prefix Either way, you are trying to “steal” someone else’s traffic by getting it routed to

you – Capture, sniff, redirect, manipulate traffic as you wish

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Source: nanog 46 preso


How does the Solution look like?

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Multicast VPN Solution Space

(complete solution is now available)

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LSM Encapsulation /Forwarding IP/GRE

P2MP TE (pt-mpt)

PIM (pt-mpt)

Core Tree Signaling

MLDP (pt-mpt | mpt-mpt)

mVPN IPv4

Native IPv6

mVPN IPv6

Service Native IPv4

BGP PIM C-Multicast Signaling

PORT


BGP customer-multicast signaling and BGP auto-discover is now added to the multicast VPN solution.

Multicast VPN – BGP Signaling

BGP as overlay allows Service Providers to capitalize on a single protocol

Auto-Discovery of PEs and Core tree/tunnel information

PE1

PE2

PE3

PE4

CE1 CE3

RR

Receiver Source

CE4 Receiver CE2 RP

BGP Auto-Discovery

BGP C-mroutes

PIM C-Join (*,G) or (S,G)

PIM C-Join (*,G) or (S,G)

Advertisement of Customer Multicast routes

BGP

78


BGP Graceful Shutdown

RFC 6198 – April 2011 Old Behaviour

– If session drops then BGP will withdraw all prefixes learned over that session

– BGP has no mechanism to signal prefix will soon be unreachable (for maintenance for example)

Historically RR’s have worsened the issue as they tend to hide the alternate path as they only forward the best path

79

BGP Graceful Shutdown allows to do maintenance on router without service disruption.

This new knob allows a router to notify neighbor to redirect traffic to other paths and after some time will drop BGP sessions.

The notification could be done using Local Preference attribute

or user community attribute

#Graceful Shutdown Please wait…

BGP/ Prefix 10.45 / localpref : 10

1 2

Traffic is redirected

3


Graceful Shutdown

GSHUT well-known community The GSHUT community attribute is applied to a neighbor specified by the

neighbor shutdown graceful command, thereby gracefully shutting down the link in an expected number of seconds The GSHUT community is specified in a community list, which is referenced by

a route map and then used to make policy routing decisions.

80

http://www.cisco.com/en/US/docs/ios-xml/ios/iproute_bgp/configuration/15-s/irg-15-s-book.pdf

neighbor {ipv4-address | ipv6-address | peer-group-name} shutdown graceful seconds {community value [local-preference value] | local-preference value}





















DDoS Mitigation – a stepstone approach

Phase III – Dynamic application aware redirection and traffic handling

Phase II – Malicious traffic mitigation – Cleaning of Malicious traffic – Dirty and clean traffic handling – Usage of Multi-instance BGP

Phase I – ACL – RTBH – PBR – uRPF

IOS-XR 4.3.1 IOS-XE partial

IOS-XR 5.2.0 IOS-XE 3.1.2

81


DDoS Overview

Distributed denial-of-service (DDoS) attacks target network infrastructures or computer services by sending overwhelming number of service requests to the server from many sources. Server resources are used up in serving the fake requests resulting in denial or degradation of legitimate service requests to be served Addressing DDoS attacks

Detection – Detect incoming fake requests Mitigation Diversion – Send traffic to a specialized device that removes the fake packets from the traffic stream while retaining the legitimate packets Return – Send back the clean traffic to the server

82


DDOS impact on Customer Business

83


DDoS mitigation architecture 1. Detection (no DDoS)

DDOS scrubber

Security Server

DDOS Analyser

Sample Netflow

Scan Netflow data to detect DDOS attacks

86


DDoS mitigation architecture 2. Detection (DDOS)

DDOS scrubber

Security Server

DDOS Analyser

Sample Netflow

Scan Netflow data Find DDOS signature

87


DDoS mitigation architecture 3. Redirect traffic to DDOS scruber

DDoS scrubber

Security Server

DDoS Analyser

Scan Netflow data Find DDoS signature

BGP DDoS Mitigation Action: redirect to DDoS scrubber

88


DDoS Mitigation: Architecture Considerations Normal traffic flow when there is no attack Redirect traffic from any edge PE to any specific DDoS scrubber

Including the PE that is connected to the host network

Granular (prefix level/network) diversion Customers buy DDoS mitigation service for some prefixes Pre-provisioned DDoS service for those prefixes (using policy such as standard community flag)

Centralized controller that injects the diversion route VPN based Labeled return path for the clean traffic

To prevent routing loops

Solution support redirection of BGP less/more specific prefixes or local originated prefixes (static route, redistributed route)

Support for multi-homed customers During attack, send clean traffic from DDOS scrubber to multiple PE’s

89


The concept

90

Traffic under normal conditions

Internet users

Traffic under normalized conditions • Traffic takes shortest path • Upstream and downstream traffic follow

traditional routing

Server Scrubber

ISP

Pre-provisioned DDoS instrumentation • Traffic Scrubber

Separate clean and malicious traffic • Security Analyser

Analyses Netflow/IPFIX statistics from the traffic flows

• Security server Actions upon traffic analysis by communication to infrastructure routers

Security analyser Security server

PE3

PE2

PE1


BGP based DDoS

91

Traffic under DDoS condition

Internet users

Traffic under DDoS condition • Traffic is redirected to a scrubber • Scrubber separates the clean from

the malicious traffic • Clean traffic is returned to original

destination server

Goal • Do not drop all traffic • Collect traffic intelligence • Operational simplicity • Easy to remove redirect when traffic

normalizes

Server Scrubber

ISP


PE3

PE2

PE1


How does it work?

92

Normal traffic condition

Internet users

• All PE’s peer with the RR • All PE’s exchange both Global

Internet and VPN prefixes • All PE interfaces are non-VPN • Security analyser is performing

doing analyses

Server Scrubber

ISP

Internet and VPN Route-Reflector

1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

5.5.5.5


Destination Next-hop

1.1.1.1/32 2.2.2.2

PE3

PE2

PE1


How does it work?

93

Server is under DDoS

Internet users

• Flow is detected as dirty by Security analyser

• Result: Server is under attack • Traffic needs to be redirected to the

scrubber to mitigate the attack Server

Scrubber

ISP


1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

5.5.5.5



1.1.1.1/32 2.2.2.2

PE3

PE2

PE1


How does it work?

94

Internet users

• DDoS Route-Reflector was pre-visioned

• Mitigation route to 1.1.1.1/32 is injected on the DDoS RR by the Security server

• Mitigation route to 1.1.1.1/32 is pointing to 3.3.3.3 on DDoS mitigation RR

Server Scrubber

ISP


1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

5.5.5.5

Security server

DDoS Route-Reflector

5.5.5.5


1.1.1.1/32 3.3.3.3

PE3

PE2

PE1



How does it work?

95

Internet users

• Mitigation route to 1.1.1.1/32 is pointing to 3.3.3.3 is signalled to all PE’s

• All PE’s receive the mitigation route from the DDoS Mitigation RR

• Each PE will now have 2 routes to reach 1.1.1.1/32

• Which route will the PE use?

Server Scrubber

ISP


1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

5.5.5.5

Security server


5.5.5.5


1.1.1.1/32 3.3.3.3


1.1.1.1/32 2.2.2.2

1.1.1.1/32 3.3.3.3


1.1.1.1/32 ????????????

BGP Table Routing Table

PE3

PE2

PE1



How does it work?

96

Internet users

Trick # 1 • The DDoS mitigation route will

ALWAYS be preferred, even if • Both prefix lengths are the

same • DDoS prefix is shorter • Original prefix has better

administrative distance

Server Scrubber

ISP


1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

5.5.5.5

Security server


5.5.5.5


1.1.1.1/32 2.2.2.2

1.1.1.1/32 3.3.3.3


1.1.1.1/32 3.3.3.3

Routing Table BGP Table

PE3

PE2

PE1



How does it work?

97

Internet users

• The mitigated traffic flows towards PE3 (3.3.3.3)

• PE3 is sending the dirty flow towards the scrubber

• The scrubber will • Handle and remove the dirty

traffic within the original flow • Send the cleaned traffic

towards the original destination (1.1.1.1 at PE2 (2.2.2.2))

Server Scrubber

ISP


1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

5.5.5.5


5.5.5.5


1.1.1.1/32 2.2.2.2

1.1.1.1/32 3.3.3.3


1.1.1.1/32 3.3.3.3


PE3

PE2

Clean traffic

PE1



How does it work?

98

Internet users

Problem • Scrubber sends traffic to PE3 • PE3 does routing lookup for 1.1.1.1

and finds that it is directly attached • ROUTING LOOP!!! • How do we fix this?

• We use a new isolated routing table for the clean traffic

• This routing table is Pre-provisioned Inside a VPN

Server Scrubber

ISP


1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

5.5.5.5


5.5.5.5


1.1.1.1/32 2.2.2.2

1.1.1.1/32 3.3.3.3


1.1.1.1/32 3.3.3.3


PE3

PE2

Clean traffic

PE1



How does it work?

99

Internet users

Server Scrubber

ISP

1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4


1.1.1.1/32 2.2.2.2

1.1.1.1/32 3.3.3.3

Destination Next-hop VPN

1.1.1.1/32 3.3.3.3 Global

1.1.1.1/32 2.2.2.2 Clean


PE3

PE2

• The clean traffic will be injected upon PE3 on an interface member of VPN Clean

• PE3 will now do a routing destination lookup for 1.1.1.1 in VPN Clean

• The matching routing table entry is pointing towards PE2 at 2.2.2.2

• The clean flow, which is now part of VPN Clean is sent towards PE2 reachable at 2.2.2.2

VPN Clean

PE1



How does it work?

100 Internet users

Server Scrubber

ISP

1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

PE3

PE2 CE1


1.1.1.1/32 3.3.3.3 Global

1.1.1.1/32 CE1 Clean

Routing Table • PE2 receives the clean flow within VPN clean

• PE2 does a destination address routing lookup in VPN clean

• A matching route is found in VPN clean

• Flow is forwarded towards CE1 onwards to Server

HOLD on a minute! PE2 does not have any interface part of VPN clean

All interfaces on PE2 are global interfaces so how did that clean route for 1.1.1.1 get into VPN

clean?

PE1



How does it work?

101 Internet users

Server Scrubber

ISP

1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4


VPN

1.1.1.1/32 CE1 Global

1.1.1.1/32 3.3.3.3 Global

1.1.1.1 CE1 clean

BGP Table

PE3

PE2 CE1

Trick # 2 • Copy the locally BGP inserted route

directly into VPN clean BGP table • Neighbour details are inherited from

the global table (i.e.) • Outgoing interface • Next-hop

• Interface pointing towards CE1 is NOT VPN aware

• This VPN clean distributed as normal VPN

• New CLI command to do that import from default-vrf route-policy ddos advertise-as-vpn


1.1.1.1/32 3.3.3.3 Global

1.1.1.1/32 CE1 Clean

Routing Table

PE1


Going back to traditional traffic flow

102

Internet users

• Remove the routing entry on the Mitigation DDoS RR

• No more route is remaining on the DDoS Mitigation RR

• Traffic flows normally again

Server Scrubber

ISP


1.1.1.1/32

2.2.2.2 3.3.3.3

4.4.4.4

5.5.5.5

Security server


5.5.5.5


1.1.1.1/32 3.3.3.3

PE1



Configuration (1)

router bgp 99 instance ddos bgp router-id 3.3.3.3 bgp read-only bgp install diversion address-family ipv4 unicast ! router bgp 99 bgp router-id 2.2.2.2 address-family ipv4 unicast !

Creation of DDoS BGP instance

Allows config of 2th IPv4 or IPv6 instance Suppresses BGP Update Generation

Triggers BGP ddos instance to install diversion path to RIB, so that the paths are pushed down to FIB

103


Configuration (2)

vrf clean address-family ipv4 unicast import from default-vrf route-policy ddos advertise-as-vpn export route-target 111:1 ! ! address-family ipv6 unicast import from default-vrf route-policy ddos advertise-as-vpn export route-target 111:1 ! ! !

Importing the global route’s in the clean VRF

104


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