xBGP : When You Cant Wait for the IETF and Vendors Thomas Wirtgen , - - PowerPoint PPT Presentation

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xBGP : When You Cant Wait for the IETF and Vendors Thomas Wirtgen , - - PowerPoint PPT Presentation

Jun 30, 2023 181 likes •685 views

xBGP : When You Cant Wait for the IETF and Vendors Thomas Wirtgen , Quentin De Coninck, Randy Bush, Laurent Vanbever and Olivier Bonaventure 1 BGP enables routing on the Internet iBGP iBGP AS 3 iBGP eBGP iBGP AS 2 iBGP eBGP eBGP

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SLIDE 1

xBGP: When You Can’t Wait for the IETF and Vendors

Thomas Wirtgen, Quentin De Coninck, Randy Bush, Laurent Vanbever and Olivier Bonaventure

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SLIDE 2

BGP enables routing on the Internet

2 eBGP eBGP eBGP iBGP iBGP iBGP iBGP iBGP iBGP iBGP iBGP iBGP iBGP

AS 1 AS 2 AS 3

iBGP iBGP

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SLIDE 3

BGP enables routing on the Internet

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BGP must be standardized to support network of multiple BGP implementations

eBGP eBGP eBGP iBGP iBGP iBGP iBGP iBGP iBGP iBGP iBGP iBGP iBGP

AS 1 AS 2 AS 3

iBGP iBGP

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SLIDE 4

Agenda

  • The Weaknesses of the Current Routing Paradigm
  • xBGP: a Paradigm Shift
  • Adding a new feature with xBGP
  • Uses Cases

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SLIDE 5

Example of rejected feature: Geo-location TLV

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draft-raszuk-idr-bgp-pr-05 AS 2 AS 3 AS 1

P

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SLIDE 6

Example of rejected feature: Geo-location TLV

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draft-raszuk-idr-bgp-pr-05 AS 3 AS 1 AS 2

P

BGP UPDATE P via AS2

Adds GeoLoc

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SLIDE 7

Example of rejected feature: Geo-location TLV

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draft-raszuk-idr-bgp-pr-05 AS 3 AS 1 AS 2

P

B G P U P D A T E P v i a A S 2 f r

  • m

L a t : 5 . 6 6 8 6 6 L

  • n

g : 4 . 6 2 1 5 3 5 B G P U P D A T E P v i a A S 2 f r

  • m

L a t : 5 . 6 6 8 6 6 L

  • n

g : 4 . 6 2 1 5 3 5 BGP UPDATE P via AS2

Adds GeoLoc

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SLIDE 8

Example of rejected feature: Geo-location TLV

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draft-raszuk-idr-bgp-pr-05 AS 3 AS 1 AS 2

P

B G P U P D A T E P v i a A S 2 f r

  • m

L a t : 5 . 6 6 8 6 6 L

  • n

g : 4 . 6 2 1 5 3 5 B G P U P D A T E P v i a A S 2 f r

  • m

L a t : 5 . 6 6 8 6 6 L

  • n

g : 4 . 6 2 1 5 3 5 BGP UPDATE P via AS2

Adds GeoLoc Removes GeoLoc

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SLIDE 9

Example of rejected feature: Geo-location TLV

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AS 1 draft-raszuk-idr-bgp-pr-05 AS 3

BGP UPDATE P via AS2 B G P U P D A T E P v i a A S 2 f r

  • m

L a t : 5 . 6 6 8 6 6 L

  • n

g : 4 . 6 2 1 5 3 5 BGP UPDATE P via AS1 AS2

AS 2

P

B G P U P D A T E P v i a A S 2 f r

  • m

L a t : 5 . 6 6 8 6 6 L

  • n

g : 4 . 6 2 1 5 3 5

Adds GeoLoc Removes GeoLoc

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SLIDE 10

The Need of Programmable Routers

Routers vendors receive a lot of feature requests

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SLIDE 11

The Need of Programmable Routers

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Routers vendors receive a lot of feature requests

“I would like feature A” “I would like features A, B & C” “I would like feature C”

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SLIDE 12

The Need of Programmable Routers

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Routers vendors receive a lot of feature requests

“I would like feature A” “I would like features A, B & C” “I would like feature C” “What about feature S ?”

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SLIDE 13

The Need of Programmable Routers

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Routers vendors receive a lot of feature requests

“I would like feature A” “I would like features A, B & C” “I would like feature C” “What about feature S ?” Small networks do not have enough impact to convince OS vendors

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SLIDE 14

Problem #1: Networks evolve, as do routing protocols

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The evolution is complex:

  • 1. Standardization by the IETF (3.5 years in average for BGP)
  • 2. Implementation on the vendor OS
  • 3. Update routers of networks
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SLIDE 15

Problem #2: Large networks use diverse routers

Vendors do not propose the same set of extensions on their routers The configuration of these routers differs as well

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Vendor A Vendor B OS Vendor A OS Vendor B

routing-options { router-id 1.1.1.1; autonomous-system 65001; } protocols { bgp { group Session-to-R1 { type external; neighbor 1.1.1.2 { peer-as 65002; } } } router bgp 65001 bgp router-id 1.1.1.1 neighbor 1.1.1.2 remote-as 65002 Simple Juniper configuration file Simple Cisco configuration file

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SLIDE 16

Agenda

  • The Weaknesses of the Current Routing Paradigm
  • xBGP: a Paradigm Shift
  • Adding a new feature with xBGP
  • Uses Cases

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SLIDE 17

xBGP: toward a paradigm shift

xBGP proposes a common interface to dynamically update any BGP implementation. Network operators can program their routers directly with plugins.

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AS 1 One plugin is injected for each router of the network

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SLIDE 18

xBGP forces routers to follow the same rules

Each router adds xBGP on top of its implementation With xBGP, routers expose a common API.

18 Plugin

Can be seen as POSIX norms

Vendor A Vendor B OS Vendor A OS Vendor B

+ xBGP + xBGP

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SLIDE 19

Agenda

  • The Weaknesses of the Current Routing Paradigm
  • xBGP: a Paradigm Shift
  • Adding a new feature with xBGP
  • Uses Cases

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SLIDE 20

Structure of xBGP

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My GeoLoc Plugin

RFC 4271 BGP Workflow

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SLIDE 21

Structure of xBGP

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My GeoLoc Plugin

RFC 4271 BGP Workflow

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SLIDE 22

Structure of xBGP

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Decoding GeoLoc Take the nearest router Serializing GeoLoc

My GeoLoc Plugin

RFC 4271 BGP Workflow

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SLIDE 23

Structure of xBGP

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Decoding GeoLoc Take the nearest router Serializing GeoLoc

My GeoLoc Plugin

RFC 4271 BGP Workflow

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SLIDE 24

Structure of xBGP

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Decoding GeoLoc Take the nearest router Serializing GeoLoc

My GeoLoc Plugin

libxBGP

RIB BGP Neighbor Sessions This router Geo Coordinates ... Internal data structure

RFC 4271 BGP Workflow

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SLIDE 25

Structure of xBGP

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Decoding GeoLoc Take the nearest router Serializing GeoLoc

My GeoLoc Plugin

libxBGP

RIB BGP Neighbor Sessions This router Geo Coordinates ... Internal data structure

RFC 4271 BGP Workflow

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SLIDE 26

Agenda

  • The Weaknesses of the Current Routing Paradigm
  • xBGP: a Paradigm Shift
  • Adding a new feature with xBGP
  • Uses Cases

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SLIDE 27

Demonstrating the programmability of xBGP

xBGP requires a little adaptation on the host BGP implementation We have adapted both FRRouting and BIRD to be xBGP compliant

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FRRouting (LoC) BIRD Routing (LoC) Modification to the codebase 30 10 Insertion Points 73 66 Plugin API 624 415 libxbgp 3004 + dependencies User Space eBPF VM 2776

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SLIDE 28

Use Cases

1. Re-implementation of route reflectors (295 LoC) 2. Expressive filters

  • Route Origin Validation (126 LoC)
  • Valley Free path check (81 LoC)

3. GeoTags attribute as MED alternative (261 LoC)

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SLIDE 29

Use Cases

1. Re-implementation of route reflectors (295 LoC) 2. Expressive filters

  • Route Origin Validation (126 LoC)
  • Valley Free path check (81 LoC)

3. GeoTags attribute as MED alternative (261 LoC)

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SLIDE 30

Valley Free path check

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S1 L10 L11 S2 L12 L13 T20 T21 T22 T23

Level 0 Level 1 Level 2

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SLIDE 31

Valley Free path check

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S1 L10 L11 S2 L12 L13 T20 T21 T22 T23

Level 0 Level 1 Level 2

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SLIDE 32

Valley Free path check

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S1 L10 L11 S2 L12 L13 T20 T21 T22 T23

Level 0 Level 1 Level 2

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SLIDE 33

Valley Free path check

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S1 L10 L11 S2 L12 L13 T20 T21 T22 T23

Level 0 Level 1 Level 2

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SLIDE 34

Valley Free path check

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S1 L10 L11 S2 L12 L13 T20 T21 T22 T23

Level 0 Level 1 Level 2

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SLIDE 35

Valley Free path check

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S1 L10 L11 S2 L12 L13 T20 T21 T22 T23

Level 0 Level 1 Level 2

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SLIDE 36

Valley Free path check

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AS 001 AS 100 AS 100 AS 001 AS 100 AS 100 AS 200 AS 200 AS 200 AS 200

Level Level 1 Level 2

MyRouterCli > show ip bgp BGP Routing table information for VRF default Router identifier 192.168.254.5, local AS number 1 Network Next Hop Metric LocPref Weight Path * >Ec 192.168.10.0/24 192.168.255.20 0 100 100 200 i * ec 192.168.10.0/24 192.168.255.4 0 100 100 200 i * >Ec 192.168.254.3/32 192.168.255.4 1 100 100 200 i * ec 192.168.254.3/32 192.168.255.20 0 100 100 200 i * >Ec 192.168.254.4/32 192.168.255.20 0 100 100 200 i

RFC7938 Use of BGP for Routing in Large-Scale Data Centers

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SLIDE 37

Valley Free path check

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AS 001 AS 100 AS 100 AS 001 AS 100 AS 100 AS 200 AS 200 AS 200 AS 200

Level Level 1 Level 2

MyRouterCli > show ip bgp BGP Routing table information for VRF default Router identifier 192.168.254.5, local AS number 1 Network Next Hop Metric LocPref Weight Path * >Ec 192.168.10.0/24 192.168.255.20 0 100 100 200 i * ec 192.168.10.0/24 192.168.255.4 0 100 100 200 i * >Ec 192.168.254.3/32 192.168.255.4 1 100 100 200 i * ec 192.168.254.3/32 192.168.255.20 0 100 100 200 i * >Ec 192.168.254.4/32 192.168.255.20 0 100 100 200 i

Where are these routes sourced from ? RFC7938 Use of BGP for Routing in Large-Scale Data Centers

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SLIDE 38

Valley Free path check with xBGP

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One plugin + one topology manifest for all routers ! CFG + (81 LoC) AS 001 AS 101 AS 102 AS 002 AS 103 AS 104 AS 201 AS 202 AS 203 AS 204

Level 0 Level 1 Level 2

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SLIDE 39

Valley Free path check with xBGP

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AS 001 AS 101 AS 102 AS 002 AS 103 AS 104 AS 201 AS 202 AS 203 AS 204

Level Level 1 Level 2 uint64_t valley_free_check(args_t *args UNUSED) { /* variable declaration omitted */ attr = get_attr_from_code(AS_PATH_ATTR_CODE); peer = get_src_peer_info(); if (!attr || !peer) return FAIL; my_as = peer->local_bgp_session->as; as_path = attr->data; as_path_len = attr->len; while (i < as_path_len) { i++; /* omit segment type */ segment_length = as_path[i++]; for (j = 0; j < segment_length - 1; j++) { curr_as = get_u32(as_path + i); i += 4; if (!valley_check(next_as, curr_as)) return PLUGIN_FILTER_REJECT; } } next(); return FAIL; }

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SLIDE 40

Valley Free path check with xBGP

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AS 001 AS 101 AS 102 AS 002 AS 103 AS 104 AS 201 AS 202 AS 203 AS 204

Level Level 1 Level 2 uint64_t valley_free_check(args_t *args UNUSED) { /* variable declaration omitted */ attr = get_attr_from_code(AS_PATH_ATTR_CODE); peer = get_src_peer_info(); if (!attr || !peer) return FAIL; my_as = peer->local_bgp_session->as; as_path = attr->data; as_path_len = attr->len; while (i < as_path_len) { i++; /* omit segment type */ segment_length = as_path[i++]; for (j = 0; j < segment_length - 1; j++) { curr_as = get_u32(as_path + i); i += 4; if (!valley_check(next_as, curr_as)) return PLUGIN_FILTER_REJECT; } } next(); return FAIL; }

Retrieve data from the host implementation

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SLIDE 41

Valley Free path check with xBGP

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AS 001 AS 101 AS 102 AS 002 AS 103 AS 104 AS 201 AS 202 AS 203 AS 204

Level Level 1 Level 2 uint64_t valley_free_check(args_t *args UNUSED) { /* variable declaration omitted */ attr = get_attr_from_code(AS_PATH_ATTR_CODE); peer = get_src_peer_info(); if (!attr || !peer) return FAIL; my_as = peer->local_bgp_session->as; as_path = attr->data; as_path_len = attr->len; while (i < as_path_len) { i++; /* omit segment type */ segment_length = as_path[i++]; for (j = 0; j < segment_length - 1; j++) { curr_as = get_u32(as_path + i); i += 4; if (!valley_check(next_as, curr_as)) return PLUGIN_FILTER_REJECT; } } next(); return FAIL; }

Retrieve data from the host implementation Main processing of the plugin

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SLIDE 42

Valley Free path check with xBGP

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AS 001 AS 101 AS 102 AS 002 AS 103 AS 104 AS 201 AS 202 AS 203 AS 204

Level Level 1 Level 2 uint64_t valley_free_check(args_t *args UNUSED) { /* variable declaration omitted */ attr = get_attr_from_code(AS_PATH_ATTR_CODE); peer = get_src_peer_info(); if (!attr || !peer) return FAIL; my_as = peer->local_bgp_session->as; as_path = attr->data; as_path_len = attr->len; while (i < as_path_len) { i++; /* omit segment type */ segment_length = as_path[i++]; for (j = 0; j < segment_length - 1; j++) { curr_as = get_u32(as_path + i); i += 4; if (!valley_check(next_as, curr_as)) return PLUGIN_FILTER_REJECT; } } next(); return FAIL; }

Retrieve data from the host implementation Main processing of the plugin The route is rejected if such a pair exists

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SLIDE 43

Conclusion

xBGP proposes a new methodology to upgrade routing protocols xBGP provides new opportunities with other routing protocols From a monolithic to a modular approach The next steps: Standardizing the API + the VM New use cases See https://www.pluginized-protocols.org/xbgp for the latest updates and the source code

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SLIDE 44

Backup slides

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SLIDE 45

Comparison with native code

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Lower is better

Time xBGP - Time Native Time Native x 100

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SLIDE 46

Comparison with native code

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Lower is better

Time xBGP - Time Native Time Native x 100

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SLIDE 47

Comparison with native code

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Native code uses a slower data structure Lower is better

Time xBGP - Time Native Time Native x 100

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SLIDE 48

Old slides

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SLIDE 49

BGP enables routing on the Internet

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SLIDE 50

xBGP: toward a paradigm shift

Extending a protocol is complex. Why not offer operators the opportunity to program/update their own extensions?

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AS 1 “Here is your plugin”