bgp-te application level topology …...bgp speaker bgp bgp speaker speaker igp router as1 prefix 1,...

1 Copyright © 2012 Juniper Networks, Inc. www.juniper.net

BGP-TE APPLICATION LEVEL TOPOLOGY INTELLIGENCE

Hannes Gredler


MOTIVATION

Look across the “fence”

“Fence” being IGP area/level or AS

boundary

Gain visibility for application(s) which need

complete topology data

ALTO

CDNI

Inter-{Area, AS} TE

High frequency API


Alto Server

BGP Speaker

BGP Speaker BGP

Speaker

IGP Router AS1

Prefix 1, 2, 3, … Prefix 11, 12, 13, …

Prefix 21, 22, 23, …

BGP Speaker

Prefix 31, 32, 33, …

Alto Client

Alto Client

Alto Client

HTTP IGP Peering

IGP Router

IGP Router

IGP Router

IGP Router

IGP Router Level 2

Backbone Area

Level 1

Non-Backbone Area

Level 1

Non-Backbone Area

Level 1

Non-Backbone Area

Level 1

Non-Backbone Area

IGP Router

HISTORICAL INSIGHT – BUILDING AN ALTO SERVER (1)

ALTO server needs to know all areas topology

Manually crafting of “IGP peering” topology is tedious and error prone !!!


HISTORICAL INSIGHT – BUILDING AN ALTO SERVER (2)

rpd

Per Protocol: FSM, Encoder, Decoder, DB, route- resolution, IPC

ALTO Server

IPC: FSM, Decoder, DB Session

IPC

BGP Peers

IGP Adjacencies

P2P Clients

DBDB

External Applications need to access rpd internal data

• BGP Internet (SAFI 1) prefixes

• IGP Topology data

Need to define an API (Session and IPC)

• PUSH or PULL model ?

• IPC format ?

• Would it make sense to “standardize” this API ?


USE CASE – INTER-REGION TRAFFIC ENGINEERING

Area 0Area 51

R2 ABR2

S

R1 ABR1

Main LSP

Bypass LSP

Area 47

R6

D

R4

R3 ABR3

ABR4

R5

SRLG 666

SRLG 666

• RSVP Loose hop expansion has practical deployment limits

• Vanilla RSVP has no crank-back in case it “sees” new information that it did

not see at previous hops. (and RFC4920 has a lot of caveats)

X


STATUS IETF WORK

draft-gredler-idr-ls-distribution-02

The protocol allows Topology data (links

and nodes) to be shared in a protocol

agnostic (no OSPFism, no IS-IS ism)

form.

Joint work with Cisco

Call for adoption as idr-wg item (Aug 31)

So far positive feedback, Usual criticism

on “BGP bloat”

Want to move further work to SDN-WG


IMPLEMENTATION IN JUNOS

• Key of IETF draft is “protocol

agnostic representation” of nodes

and links

• Wait a bit – don’t we have something

like this already in JUNOS ???

• Yes its called the Traffic

engineering database (TED)

hannes@R1> show ted link detail

TED database: 0 ISIS nodes 3 INET nodes

ID Type Age(s) LnkIn LnkOut

Protocol

10.0.0.1 Rtr 1013 1 1

OSPF(0.0.0.0)

To: 192.168.56.204-1, Local: 192.168.56.201, Remote:

0.0.0.0

Local interface index: 0, Remote interface index: 0


Protocol

*192.168.56.204* *Rtr *1011 1 1 OSPF(0.0.0.0)

*To: 192.168.56.204-1*, Local: 0.0.0.0, Remote: 0.0.0.0



Protocol

*192.168.56.204-1* *Net *1011 2 2 OSPF(0.0.0.0)

To: 10.0.0.1, Local: 0.0.0.0, Remote: 0.0.0.0


*To: 192.168.56.204*, Local: 0.0.0.0, Remote: 0.0.0.0

Local interface index: 0, Remote interface index: 0 => Need to transcode node/links

information from/to TED into BGP


TRANSCODING TE LINK INFO INTO BGP NLRI

Carried in

MP_REACH_NLRI path attribute

MP_UNREACH_NLRI path attribute

LS_ATTRIBUTES path attribute

Two NLRI types

Node

Link

Each NLRI describes a single link anchored by at least a pair of router-IDs

Link may be anchored by more than one pair of Router-IDs

Negotiated between BGP speakers using BGP-MP Capability


TED NLRI TYPES: NODES AND LINKS

9


ROUTER-ID ANCHORING EXAMPLE: ISO PSEUDONODE

• Broadcast LAN between a pair of routers: – “Real" (=non pseudonode) routers have both an IPv4 Router-ID and IS-IS Node-IDs

– The pseudonode does not have an IPv4 Router-ID.

• Two unidirectional links being generated:

• NRLI #1for (R1, Pseudonode) encodes: – local IPv4 router-ID, local ISO node-ID and remote ISO node-id

• NLRI #2 for (Pseudonode, R2) encodes: – local ISO node-ID, remote IPv4 router-ID and remote ISO node-id.


STATE FLOW

peer

bgp.traffic-engineering

BGP Import policy BGP Export policy

peer

TED

TED export policy TED import policy


TRAFFIC ENGINEERING RIB

hannes@R1> show route table bgpte.0

bgpte.0 : 7 destinations, 7 routes (7 active, 0 holddown, 0 hidden)

+ = Active Route, - = Last Active, * = Both

*LINK { Local { IPv4:10.0.0.1 } Remote { IPv4:192.168.56.204 } OSPF:0 }/576

*[OSPF/512] 00:16:50

Fictitious


*[OSPF/512] 00:16:48

Fictitious


*[OSPF/512] 00:16:48

Fictitious

*LINK { Local { IPv4:88.0.0.100 ISO:0880.0000.0100.00 } Remote { ISO:0880.0000.0101.02 } ISIS-L1:0 }/576

*[BGP/170] 00:09:31, localpref 100, from 88.0.0.100

AS path: I

Fictitious



AS path: I

Fictitious



AS path: I

Fictitious


BGP-TE SUMMARY

Distribution of node and link data beyond IGP boundaries

Enables Inter {Area,Domain} C-SPF signaling

JUNOS Implementation available for testing in Q3 2012

Please contact Nitin Bahadur ([email protected]) in case you want to test-ride

That’s cool, but is there anything beyond ?

mailto:[email protected]


TRAFFIC ENGINEERING 2.0


TRAFFIC ENGINEERING 2.0 – THE PROBLEM

AS 1

AS1

R2 ASBR2

S

R1 ASBR1

ASBR4

ASBR6

ASBR3

ASBR5

AS 2

91/8

91/8

91/8

91/8


ADD A RSVP-TE-LSP –

AS 1

AS1

R2 ASBR2

S

R1 ASBR1

ASBR4

ASBR6

ASBR3

ASBR5

AS 2

91/8

91/8

91/8

91/8RSVP-TE LSP


COMMON TRAFFIC ENGINEERING PROBLEMS

RSVP-TE LSPs are big Hammers

Lack of egress Control

Node control vs. Link control, ideally per prefix …

Low frequency (sensor) update

TE stats available through SNMP/CLI/File uploads

Low frequency (actor) update

Human interaction

Machine based: Through Config Transactional Interface


1ST ADD A HIGH-FREQUENCY MP2MP SIGNALING API

AS 1

AS1

ASBR4

ASBR6

ASBR3

ASBR5

AS 2

91/8

91/8

91/8

91/8

R2 ASBR2

S

R1 ASBR1

TE-APPRR


2ND ADD FURTHER NLRI TYPES TO BGP-TE

Traffic statistics

Interface & TE LSPs

TE LSP status report

Discover MPLS LSPs

Targeted TE LSP setup

(P2P, Protection, P2MP)

IP Prefix to TE Tunnel mapping

(=granular control)

Egress Nexthop control

Add indirection-Layer through BGP-TE


PUTTING IT ALL TOGETHER ….

• Use Labeled-BGP to discover

remote routers

• Preserve BGP NH of Internet

routes

• Program WAN links to send high

frequency traffic stats

• Setup LSP Transport mesh

(=more than one) for desired

core-link loading

• Send Prefix / Tunnel Map

message to control binding of

Prefixes to LSPs / and BGP NHs

AS 1

AS1

ASBR4

ASBR6

ASBR3

ASBR5

AS 2

91/8

91/8

91/8

91/8

R2

R1

TE-APPRR

S

ASBR1

ASBR2

RSVP-TE LSP #2

MAP 17% 91/8, LSP #1, BGP-NH {ASBR4}

RSVP-TE LSP #1





SUMMARY & FUTURE

BGP-TE is is foundation for software-defined networking in JUNOS

Topology discovery

TE LSP discovery and setup

IP Prefix to TE Tunnel mapping

High-frequency API

In IETF speak we call this “BGP-TE southbound API”

Internet-draft on BGP-TE Southbound to be published

after SDN-wg constitution, IETF85 Atlanta

bgp-te application level topology …...bgp speaker bgp bgp speaker speaker igp router as1 prefix 1,...

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