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Enhanced Efficiency of Mapping Distribution Protocols in Scalable Routing and Addressing Architectures K. Sriram, Patrick Gleichmann, Young-Tak Kim, and Doug Montgomery July 2010 National Institute of Standards and Technology National

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SLIDE 1

National Institute of Standards and Technology National Institute of Standards and Technology

Contact: Contact: ksriram@nist.gov ksriram@nist.gov

Enhanced Efficiency of Mapping Distribution Protocols in Scalable Routing and Addressing Architectures

  • K. Sriram, Patrick Gleichmann, Young-Tak Kim, and Doug Montgomery

July 2010

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Acknowledgement: Thanks to Dino Farinacci, Lixia Zhang, Joel Halpern, and Robin Whittle for their helpful comments and suggestions.

This research was supported by the Department of Homeland Security under the Secure Protocols for the Routing Infrastructure (SPRI) program and the NIST Information Technology Laboratory Cyber and Network Security Program.

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SLIDE 2

Background

  • This work was originally presented in RRG in

July 2007 at the Dublin IETF Meeting.

  • A revised version was presented at the IETF

LISP WG meeting in March 2010. This current version reflects revisions based on feedback from that meeting.

  • Slides 6, 8, 9, and 14-17 have new or

significantly revised material.

  • Detailed updated document is at:

http://www.antd.nist.gov/~ksriram/EEMDP_ICCCN2010.pdf

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SLIDE 3

AS1

Control Plane (Signaling) Forwarding Plane ID/Loc mapper query (ID/Loc mapping info request, response) registration

  • f (ID/Loc

mapping info) cache

TR TR

IP-over-IP map-n-encap

AS4

Mapping Distribution Network

Pull Push

ITR1 ETR1

Source Network Destination Network

BGP (core Internet) (based on locator) Delivery networks

(based on ID)

ILM-R ILM ILM ILM-R ILM ILM Query Response

Push

Push Pull ILM = ID Locator Mapping server ILM-R = ILM-Regional

Overview of Map and Encap Solution

3

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SLIDE 4

ETR1

Parent ETR for a/20

ETR2 ETR3

ILM-R ILM ILM ILM-R ILM ILM

ITR1

Map: (a/20, ETR1, Exceptions: a7/24, a14/24) Map: (a14/24, ETR2) Map: (a7/24, ETR3)

Query: a6

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(a/20, ETR1) (a14/24, ETR2) (a7/24, ETR3) Response: Response: MS = 1 indicates existence of More Specific(s) of this prefix at different ETR(s).

Push Pull ILM = ID Locator Mapping server ILM-R = ILM-Regional

[a0/24, … , a6/24, a8/24, … a13/24, a15/24] (Note: Most of a/20 is here; except subprefixes a7/24 and a14/24 which are elsewhere)

Packet destined to an address a6

1 in a6/24 Query: a6

1

a14/24 a7/24

(a/20, ETR1, MS=1)

Managing Holes in Maps (Preview)

4

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SLIDE 5

Real-World Example: Hole in a PI Address

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Announced in BGP‐4: Aggregate 129.6.0.0/17 Origin: AS49 More Specific 129.6.112.0/24 Origin: AS10886 EID to Locator Mapping: EID: ETR (equivalent) 129.6.112.0/24 ETR10886 129.6.113.0/24 ETR49 129.6.114.0/23 ETR49 129.6.116.0/22 ETR49 129.6.120.0/21 ETR49 129.6.96.0/20 ETR49 129.6.64.0/19 ETR49 129.6.0.0/18 ETR49

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SLIDE 6

Proliferation of Map Entries

6 129.6.112.0/24 ETR 10886 129.6.113.0/24 ETR 49 129.6.114.0/23 ETR 49 129.6.116.0/22 ETR 49 129.6.120.0/21 ETR 49 129.6.96.0/20 ETR 49 129.6.64.0/19 ETR 49 129.6.0.0/18 ETR 49 129.6.112.0/23 129.6.112.0/22 129.6.112.0/21 129.6.112.0/20 129.6.96.0/19 129.6.64.0/18 129.6.0.0/17

Aggregate Hole / Exception Illustration of extra set of map entries that become necessary due to a hole (in map and encap protocols) (w/o the proposed EEMDP solution)

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SLIDE 7

1 10 100 1000 10000 100000

11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 32

Subprefix Length (x)

# Subprefixes of Length x such that Each has a Less Specific with a Different Origin AS as Compared to the Subprefix

Measurement of # Prefix Holes

7 Based on Routeviews RIBs trace data – Feb 2010

Total # holes = 60988

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SLIDE 8
  • Avg. Map Multiplication Factor Due to Holes

8 Based on Routeviews RIBs trace data – Feb 2010

Overall

  • avg. =

9.37

(w/o the proposed EEMDP solution)

2 4 6 8 10 12 14 16

11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 32

Subprefix Length (x)

  • Avg. Map Multiplication Factor due to

Holes of Subprefix Length x

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SLIDE 9

Measurement of Proliferation of Maps

9 Based on Routeviews RIBs trace data – Feb 2010

Total # Extra Maps in Database = 510508 (Approx.) (w/o the proposed EEMDP solution)

1 10 100 1000 10000 100000 1000000 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 32

Subprefix Length (x) # Maps in Database

(Due to Effects of Holes of Subprefix Length x)

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SLIDE 10

Details of the Proposed Algorithm: Enhanced Efficiency of Mapping Distribution Protocols (EEMDP)

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SLIDE 11

ETR1 ETR2 ETR3

ILM-R ILM ILM ILM-R ILM ILM

ITR1

Query: a6

1

(a/20, ETR1) Response:

ILM = ID Locator Mapping server ILM-R = ILM-Regional

a/20 is entirely here; no except subprefixes

Packet destined to an address a6

1 in a6/24 Query: a6

1

Case 1: More-Specifics (Holes) Absent

MS = 00 (a/20, ETR1) Response: 11

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SLIDE 12

ETR1

Parent ETR for a/20

ETR2 ETR3

ILM-R ILM ILM ILM-R ILM ILM

ITR1

a14/24 a7/24

Query: a6

1

(a/20, ETR1) (a14/24, ETR2) (a7/24, ETR3) Response:

ILM = ID Locator Mapping server ILM-R = ILM-Regional

[a0/24, … , a6/24, a8/24, … a13/24, a15/24] (Note: Most of a/20 is here; except subprefixes a7/24 and a14/24 which are elsewhere)

Packet destined to an address a6

1 in a6/24 Query: a6

1

Case 2: All More-Specifics Communicated

MS = 01 (a/20, ETR1) (a14/24, ETR2) (a7/24, ETR3) Response: 12

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ETR1 ETR2

ILM-R ILM ILM ILM-R ILM ILM

ITR1

a14/24

Query: a6

1

(a/20, ETR1) (a14/24, ETR2) (a7/24, RR) Response:

ILM = ID Locator Mapping server ILM-R = ILM-Regional

Packet destined to an address a6

1 in a6/24 Query: a6

1

Case 3: Exception More-Specific Communicated without ETR Info (Lots of Mobile Nodes)

MS = 10 (a/20, ETR1) (a14/24, ETR2) (a7/24, RR) Response: 13

a7/24

EIDs from a7/24 are assigned to mobile nodes which are homed to different ETRs

[a0/24, … , a6/24, a8/24, … a13/24, a15/24] (Note: Most of a/20 is here; except subprefixes a7/24 and a14/24 which are elsewhere)

ETR = RR means Re- Request (i.e., send map request) if destn. EID in that more- specific prefix

Parent ETR for a/20

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SLIDE 14

ETR1

Parent ETR for a/20

ETR2 ETR3

ILM-R ILM ILM ILM-R ILM ILM

ITR1

Map: (a/20, ETR1, Exceptions: a7/24, a14/24) Map: (a14/24, ETR2) Map: (a7/24, ETR3)

Query: a6

1

(a/20, ETR1) (a14/24, ETR2) (a7/24, ETR3) Response: Response: MS = 11 indicates existence of More Specific(s) of this prefix at different ETR(s), and that only a prioritized subset of those are included in this map message.

[a0/24, a2/24, … , a6/24, a8/24, … a11/24, a13/24 a15/24] (Note: Most of a/20 is here; except subprefixes a7/24 and a14/24 which are elsewhere)

Packet destined to an address a6

1 in a6/24 Query: a6

1

a14/24 a7/24

(a/20, ETR1, MS=11) (a1/24, ETR4)

Case 4: Prioritized Subset of Maps for Exception More- Specifics Are Communicated

a1/24 a12/24

ETR4

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SLIDE 15

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MS = More Specific indicator K = # Maps to follow NE = Number of Exceptions ( NE > K) If for a more specific prefix, ETR = RR, it means ITR needs to query (Re-Request) for destination EID in that more-specific prefix

Conceptual Format for the Enhanced Map Response

Prefix K NE ETR MS More Specific Map 1 More Specific Map K .... More Specific Map 2

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SLIDE 16

Algorithm Description

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More Specific Indicator (MS) # Exception Maps Included (K) Total # Exceptions (NE) Interpretation

00

Map response has no exceptions.

01 k ne = k

Map response has exceptions; All k map responses for the exception subnets are included.

10 k ne = k

Map response has exceptions; All k map responses for the exception subnets are included but the ETR information for one or more specific subnets is “Re-request”; Subnets are further split into micro-subnets (e.g., mobile devices homed to different ETRs).

11 k (k < ne ) ne

Map response has exceptions; # Exceptions exceeds threshold (H); Only a subset of exception maps is included; Maps for prioritized (frequently requested) subset of more specifics are included.

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Comparison of Max # Map Responses Attributable to Holes w/o and with EEMDP

17 Based on Routeviews RIBs trace data – Feb 2010

Reduction achieved with EEMDP = 90%

100000 200000 300000 400000 500000 600000

Map-n-Encap w/o EEMDP Map-n-Encap with EEMDP

Max # Map Responses Communicated due to Holes

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SLIDE 18

ETR1 ETR2 ETR3 ETR4 ETR5 ETR6 ETR7 ETR8

x1/24 y0/24 x0/24 x2/24 x3/24 y1/24 y2/24 y3/24 z1/24 z2/24

ILM-R

Map: (y/22, ETR8) Map: (x3/24, ETR8, backup = yes) Map: (z2/24, ETR4) Map: (x/22, ETR7) Map: (y0/24, ETR7, backup = yes) Map: (z1/24, ETR2)

Multi-homing

Endpoint ID Aggregation at ETRs

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Conclusions and Future Work

  • Holes in ID-to-locator maps cause undesirable map

proliferations

  • Significant reduction in map entries and map

query/response traffic load is possible with the proposed EEMDP scheme

  • Substantial reduction in load on ITR’s memory and

processor

  • More accurate quantification of benefits can be performed
  • Also introduced the notion of a loose hierarchy of ETRs with

the potential benefit of aggregation of their EID address spaces

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