Address Resolution for GMPLS controlled PSC Ethernet Interfaces draftaliarpovergmplscontrolledethern

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Address Resolution for GMPLS controlled PSC
Ethernet Interfaces draft-ali-arp-over-gmpls-con
trolled-ethernet-psc-i-04.txt
Zafar Ali (zali_at_cisco.com) Hassan Sheikh
(hassans_at_cisco.com) Tomohiro Otani
(otani_at_kddilabs.jp)
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Agenda

• How comments are addressed?
• Summary of proposed recommendations.
• Next Steps.

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Change History

• Summary of the minutes of CCAMP meeting at IETF
  67 (http//www3.ietf.org/proceedings/06nov/minutes
  /ccamp.html)
• Agreed on defining a common addressing scheme
  for ARP Resolution.
• No extension to RSVP-TE for this purpose.
• The version 03 was updated accordingly.
• Version 04 addresses comments received from CCAMP
  meeting at IETF 68.

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Scope of the Draft
Non-Ethernet IF
LSP
10.1.1.2
10.1.1.3
Router 1
OXC2
Non-Ethernet IF
Ethernet IF
Non-Ethernet IF
OXC1
OXC3
Ethernet IF
Non-Ethernet GMPLS Network
Router 2
OXC4

• Issues with the use of ARP over GMPLS controlled
  Ethernet router-to-router (PSC) interfaces
  transiting from a non-Ethernet core, e.g., FSC or
  LSC GMPLS core.
• In this case, GMPLS LSP is using Ethernet
  encoding.
• When an LSP Path is established between the
  Ingress Router to Egress Router, Ethernet
  interface at the two routers comes up. However,
  before this LSP (or interface) can forward any IP
  traffic, MAC address of the remote router needs
  to be learned.

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ARP resolution on GMPLS LSP using Eth framing
GMPLS LSP
192.168.1.1/29
192.168.1.2/29
Eth link
Eth link
OXC
ARP reuest
Router 2
Router 1
ARP response
Send L3 packet to router 2
Router 1 needs to send packet to Router 2.
The following information is required (1) SRC IP
address (2) DST IP address (3) SRC MAC and (4)
DST MAC.
Step 1 -
Router 1 knows (1), (2) and (3) but does not
know (4). It needs to associate L3 Network Layer
with L2 data link layer address, i.e., need DST
MAC address to send the packet to Router 2.
Step 2 -
Router 1 sends out an ARP query requesting the
MAC address corresponding to the IP address
192.168.1.2.
Step 3 -
Router 2 responds with the MAC address as the
IP address is local to router 2
Step 4 -
Router 1 now knows (1), (2), (3) and (4) from
step 1. It can send L3 traffic to router 2 now
Step 5 -
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Inter-op Issues in resolving ARP

• Inter-op issues in resolving ARP among vendors
  found at various public events/ private testing
  efforts.
• Some routers send ARP request for the address
  of the TE link at the end-point.
• Some LSRs send ARP request using the tunnel IF
  address at the end-points.
• Some vendors do not reply to ARP request sent
  to the loopback address. Also, should the
  loopback interface address from optical or packet
  instance be use.
• Solution At IETF 67 meeting we agreed to define
  a common addressing scheme for ARP Resolution.
• An LSR SHOULD use address from packet network
  (and not the TE link address of the optical link)
  for ARP request.

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ARP Round-trip Delay

• ARP round-trip delay before traffic can be
  forwarded to the protecting LSP, when doing a
  cutover to a "cold standby" LSP (e.g., 11 Case).
• In 11 or 1N protection without extra traffic,
  the protecting LSP cannot carry any traffic until
  the traffic is switchover.
• End-point MAC address needs to be re-learned once
  the ARP cache entries time-out, or every time the
  path taken by the GMPLS LSP changes (e.g., due to
  re-routing or re-optimization).
• The Round Trip latency implies traffic loss
  (i.e., no O(50 msec) guarantees).
• Solution Assign stable virtual MAC address that
  can share with the both Ethernet IF (protection
  and working).

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Next Steps

• We need to do a revision based on the comments
  received.

Thank You
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Backup Slides
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Why not use gratuitous ARP ??
GMPLS LSP
192.168.1.1/29
192.168.1.2/29
Eth link
Eth link
OXC
ARP reuest
Router 2
Router 1
ARP response

• Gratuitous ARP could mean both gratuitous ARP
  request or gratuitous ARP reply. Gratuitous in
  this case means a request/reply that is not
  normally needed according to the ARP
  specification (RFC 826) but could be used in some
  cases. A gratuitous ARP request is an Address
  Resolution Protocol request packet where the
  source and destination IP are both set to the IP
  of the machine issuing the packet and the
  destination MAC is the broadcast address
  ffffffffffff.
• Every time an IP interface or link goes up, the
  driver for that interface will typically send a
  gratuitous ARP to preload the ARP tables of all
  other local hosts.
• Pros Automatic Detection of MAC address of the
  remote node (in p2p) and/or link up down event.
• Cons For GMPLS we have seen that this mechanism
  is unreliable because
• Transmitted once only so if missed will not be
  sent again. We have seen cases in our testing
  where one side know the MAC address of the other
  side but the other side does not know anything as
  it missed out the gratuitous ARP sent to it.
• Issue when ARP cache times out e.g. in case there
  is no activity on the data link. PR protection
  LSP is the perfect example of a GMPLS application
  where this is seen.