Operations and Maintenance Next Generation Requirements

1
Operations and Maintenance Next Generation
Requirements

• draft-amante-oam-ng-requirements-01
• Shane Amante
• Alia Atlas
• Andrew Lange
• Danny McPherson
• March 10, 2008

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Overview

• Why use LAG, ECMP?
• Background
• Use Cases
• Intra- vs. Inter-AS OAM Requirements
• Path Capabilities

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Why use LAG, ECMP?

• LAG, ECMP and ECMP over LAG are used to increase
  virtual bandwidth between two, or more,
  adjacent nodes.
• Why not just use larger links (e.g. 40G, 100G)
  and avoid these problems?
• Because the problems discussed in this draft
  still exist with N x 40G, N x 100G, etc.

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Background Goals

• Inspired by draft-atlas-icmp-unnumbered
• This memo defines ICMP extensions through which
  an router or host can explicitly identify the
  interface upon which an undeliverable datagram
  arrived. The incoming interface can be
  identified by ifIndex, name, and/or address. The
  extensions defined herein are particularly useful
  when troubleshooting networks with unnumbered
  interfaces, parallel interfaces and/or asymmetric
  routing.
• Goal Specify requirements to enhance IP MPLS
  traceroute and ping to identify and exercise
  specific paths through links consisting of LAG,
  ECMP and ECMP over LAG.
• i.e., update traceroute/ping for the 21st
  century.
• Prefer one solution, which addresses
• Intra-AS Lots of information returned to
  originator
• Inter-AS Limited/Select information returned to
  originator

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Scenario 1 Traceroute thru Routed Hops
LAG-1
LAG-2
Intf-2 10.1.1.2/30
Intf-4 10.5.1.2/30
R1
R2
R3
A1
A2
D1
D2
B1
B2
C1
C2
E1
E2
Intf-1 10.1.1.1/30
Intf-3 10.5.1.1/30

• During traceroute from R1 to R3, need to know
• Actual component-links used on output and input
  for a particular users microflow. If no
  response from R3, want to know output
  component-link used by R2 to get to R3.
• If using legacy ping, from R1 to R3, it is not
  guaranteed to be hashed onto same LAG or ECMP
  component-links as end-user traffic.

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Scenario 2 Traceroute thru 1 Switched Hop
LAG-1
LAG-2
Intf-2 10.1.1.2/30
R1
SW1
R2
A1
A2
C1
C2
D1
D2
B1
B2
E1
E2
Intf-1 10.1.1.1/30

• Mostly the same as Scenario 1, except puts more
  emphasis on the need to
• Have R1 return outgoing component-link ID, in
  cases where SW1 dies.
• In addition, because SW1 makes an independent
  hashing decision on IP/MPLS packets need R2 to
  return incoming component-link ID.

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Scenario 3 Traceroute thru 2 Switched Hops
LAG-1
LAG-3
LAG-2
Intf-2 10.1.1.2/30
R1
SW2
R2
SW1
A1
A2
E1
E2
C1
C2
F1
F2
B1
B2
G1
G2
D1
D2
Intf-1 10.1.1.1/30

• Scenario common in Enterprise or DataCenter
  environments.
• SW1 SW2 commonly understand how to load-hash
  based on outer IP and/or MPLS payloads to make
  effective use of bandwidth between them.
• Legacy traceroute is ineffective because you
  will not know the identity of component-links
  between SW1 lt-gt SW2.
• Legacy ping is ineffective because traffic is
  not guaranteed to use component-links as end-user
  traffic between SW1 lt-gt SW2 lt-gt R2.

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Other scenarios

• ECMP TBD
• Proxy Traceroute/Ping
• Need for functionality similar to
  draft-ietf-mpls-remote-lsp-ping
• PTR/PTP are important, in order to scale
  automated performance monitoring of larger
  networks.
• Performance Monitoring
• Used for automatically proactively detecting
  (soft) failures in the network.
• Discuss differences between
• Proactive Periodic Perf. Monitoring
• Proactive Perpetual Perf. Monitoring

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Intra-AS OAM Reqmts

• Must work with IP and MPLS
• Traceroute Probe Requests
• Ability to specify input keys to hash/ECMP
  algorithm, (e.g. 5-tuple for IP), in probe
  payload to exercise hash algorithm with real
  customer traffic.
• Traceroute Probe Replies
• Incoming Interface Name ( Descr)
• Outgoing Interface Name ( Descr)
• of component-links in a bundle
• BW Utilization on interface(s)
• Remote Link-Layer neighbor name Interface Name
• Required for automatically identifying Layer-2
  switched hops
• Ping
• Ability to input keys to hash/ECMP algorithm,
  (e.g. 5-tuple for IP), in probe payload to
  exercise hash algorithm with real customer
  traffic.
• MUST follow data plane for forwarding within the
  network elements.
• Proxy Traceroute/Ping Support
• Used by Network Monitoring systems to proactively
  exercise paths through network similar to MPLS
  LSR self-test.
• Need some form of (lightweight) authentication
  for Intra-AS OAM to only reveal detailed network
  knowledge to trusted entities.
• Also, recommend that dropping OAM packets may be
  necessary to prevent starvation of resources
  within network elements.

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Inter-AS OAM Reqmts

• Must work with IP and MPLS
• For example customer peering links
• Traceroute Probe Requests
• Ability to specify input keys to hash/ECMP
  algorithm, (e.g. 5-tuple for IP), in probe
  payload to exercise hash algorithm with real
  customer traffic.
• Traceroute Probe Replies
• Incoming Interface Name
• Outgoing Interface Name
• Ping
• Ability to specify input keys to hash/ECMP
  algorithm, (e.g. 5-tuple for IP), in probe
  payload to exercise hash algorithm with real
  customer traffic.

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Path Capabilities

• Probe before traceroute? Or,
• Designate special label/codepoint for new OAM
  protocol?
• Draft currently recommends latter approach to
  deterministically deal with cases of oscillating
  links and/or paths.

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Comments? Questions?