Odp500059 Bfd Technology Issue1.0_20070312_a
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Transcript of Odp500059 Bfd Technology Issue1.0_20070312_a
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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
ODP500059 BFD Technology
ISSUE 1.0
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Objectives
Upon completion of this course, you will be able to:
Describe BFD Technologies Evolution
Describe BFD Technologies Principle
Describe BFD Application
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1.1. Technology HistoryTechnology History
2.2. Technology AnalysisTechnology Analysis
3.3. Technology ApplicationTechnology Application
4.4. Standard ReferenceStandard Reference
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
The Problem of Failure Detection
An increasingly important feature of networking equipment is the rapid detection of communication failures between adjacent systems, in order to more quickly establish alternative paths.
Currently, detection can come fairly quickly in certain circumstances when data link hardware comes into play (such as SONET alarms) .
However, there are media that do not provide this kind of signaling (such as Ethernet), and some media may not detect certain kinds of failures in the path, for example, failing interfaces or forwarding engine components.
Simple situation is that link line connected to Optical network. When Optical internal link down, router does not know.
Another is when two router connect to by LAN switch .When LAN switch fails. The Ethernet interface between Router and Switch still works. But the connection of two routers fails.
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Technology History
Routing protocol30S hello
Routing protocol30S hello
1.1.1.1/30 1.1.1.2/30
Routing protocol30S hello
Routing protocol30S hello
1.1.1.1/30 1.1.1.2/30
ms BFD message based on UDP
ms BFD message based on UDP
Interface is up
Interface is up
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Technology History
If the SDH system between two router is down, but the link between SDH
and router is still up. So The unique way to detect the status of link is by
protocol with long time;
We need one mechanism to detect the end-to-end failure and provide
protection of link.
SDHSDH
X
Routing protocol Hello
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
BFD Protocol Overview
Faster convergence of routing protocols, particularly on shared media (Ethernet)
Semantic separation of forwarding plane connectivity and control plane connectivity
Detection of forwarding plane-to-forwarding plane connectivity (including links, interfaces, tunnels etc.)
A single mechanism that is independent of media, routing protocol, and data protocol
Requiring no changes to existing protocols
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Mile-stone of BFD
• Aug 04 Submit the base protocol specification to theIESG to be considered as a Proposed Standard.
• Aug 04 Submit BFD encapsulation and usage profile for single-hop IPv 4 andIPv 6 adjacencies to the IESG to be considered as a Proposed Standard
Aug 04 Submit BFD encapsulation and usage profile for MPLSLSPs to the IESG to be considered as a Proposed Standard
Nov 04 Submit BFD MIB to the IESG to be considered as Proposed Standard.
Feb 05 Submit BFD encapsulation and usage profile for multi-hop IPv 4 andIPv 6 adjacencies to the IESG to be considered as a Proposed Standard
Draf t base-002004.7
Draf t base-012005.2
Draf t base-022005.3 Draf t base-03
2005.7
•
•
•
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1.1. Technology HistoryTechnology History
2.2. Technology AnalysisTechnology Analysis
3.3. Technology ApplicationTechnology Application
4.4. Standard ReferenceStandard Reference
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
BFD Packet Architecture
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
Vers DiagST
ATP F C A D R Detect Mult Length
My Discriminator
Your Discriminator
Desired Min TX Interval
Required Min RX Interval
Required Min Echo RX Interval
From:draft-ietf-bfd-base-03.txt
• For Ethernet media, packet content is Ethernet + IP + UDP + BFD• For BFD control packet, UDP port is 3784
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
BFD -- Two BFD Modes
Asynchronous Mode Control packets flow in each
direction
Echo Mode Slower control packets, echo
packets loop through remote system
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
down
Packet transmit
down
init
init
down => init
init => up
down => init
init => up
A B
:Point of changing state
(in sending packet)
: Point of changing state(Local)
XX => YY : Resault of changingstate (Local)
BFD DOWN : DOWN state in packet
BFD INIT : INIT state in packet
BFD UP : UP state in packet
BFD Session Connection Establishment
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
BFD Detection Time
Asynchronous Mode In Asynchronous mode , detection location is at the peer side. Detection Time = Peer DM(the value of Detect detect-multiplier
received from the remote system) * max ( bfd.RMRI (bfd RequiredMinRxInterval), last received DMTI( Desired Min Tx Interval ).
Echo Mode In Echo Mode , detection location is at the local side. Detection Time = bfd.DM * max( bfd.RMRI,last received DMTI).
Attention: Don’t think it is the fixed RMRI and DMTI. Generally it is assigned by the link, delay and jitta.For Example, the transmission link is 1ms delay for 200KM.So you can first ping the link node or calculate.
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
BFD Configuration
Step Action Command
1 Enter system view. system-view
2 Enter BFD configuration view.
bfd cfg-name [ bind peer-ip ip-address
[ interface interface-name interface-type
interface-number]
3Configure the local or remote
discriminator.discriminator { local discr-value | remote discr-value }
4Configure the minimum sending
interval.min-tx-interval interval
5Configure the minimum receiving
interval.min-rx-interval interval
6 Configure the local detection multiplier. detect-multiplier multiplier
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1.1. Technology HistoryTechnology History
2.2. Technology AnalysisTechnology Analysis
3.3. Technology ApplicationTechnology Application
4.4. Standard ReferenceStandard Reference
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
BFD Application
IGP liveliness detection
Edge network availability
Host reach ability (e.g. media gateways)
Switched Ethernet integrity
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
BFD for IGP
ISIS Neighbor
BFD Neighbor
RouterA RouterB
BFDBFD
Shows a simple network with two routers running ISIS and BFD. • When ISIS discovers a neighbor it sends a request to the local BFD
process to initiate a BFD neighbor session with the ISIS neighbor router. • The BFD neighbor session with the ISIS neighbor router is established .• The BFD neighbor session with the ISIS neighbor router is torn down• BFD notifies the local ISIS process that the BFD neighbor is no longer reachable• The local ISIS process tears down the ISIS neighbor relationship
192.168.10.2 192.168.10.1
ISIS ISIS
Interface interface-type interface-numberIsis fast-sense
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
R
R
Layer2 link
Layer2 link TSR
TSR
MGW
IP Core
BFD
BFD Application in Media Gateway
• BFD protocol is completely integrated with the media gateway platform and is used to keep the connection between the gateway and the edge router.
• BFD protocol can detect failures in the Ethernet or independent network segment.
• BFD protocol can alternatively build redundant paths between the gateway and the router. Once failures are detected and confirmed, the BFD can trigger a corresponding changeover mechanism in all routes, transmission, and tunnel systems to ensure network reliability.
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
VRRP + BFD
BFD is based on the unicast. But VRRP is based on the multicast . So in fact VRRP + BFD solve the 90% issues. If there several VRRP routers. Then VRRP + BFD can not solve the problem. When we apply the BFD + VRRP, we can reduce the time from 3s ( 1S for VRRP hello , 3times ) to less than 500ms.
10.100.10.11
10.100.10.12 10.100.10.13 10.100.10.14
10.100.10.1
10.100.10.2 10.100.10.3
Dts A
,Src
10.100.10.12, next
hop 10.100.10.1
Dst
A,
Src
10.1
00.1
0.12
, nex
t
hop
10.1
00.1
0.1
BFD detection
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Mobile IP Bearer Network
The CMCC national IP backbone is the biggest Softswitch Bearer Network in the world, which is a total solution deployed with Huawei’s IP Bearer and Softswitch products.Carrier-class network design and service deployment; end-to-end total solution; abundant commercial experience based on Expert Teams from different areas.Carrier-class reliability; switch over time<=50ms; carrier-class QoS guarantee; CAC mechanism.
The CMCC national IP backbone is the biggest Softswitch Bearer Network in the world, which is a total solution deployed with Huawei’s IP Bearer and Softswitch products.Carrier-class network design and service deployment; end-to-end total solution; abundant commercial experience based on Expert Teams from different areas.Carrier-class reliability; switch over time<=50ms; carrier-class QoS guarantee; CAC mechanism.
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UMG8900
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NE5000E NE5000E
SoftX3000
UMG8900
UMG8900
SoftX3000
SoftX3000
UMG8900
UMG8900
UMG8900
NE40E
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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1.1. Technology HistoryTechnology History
2.2. Technology AnalysisTechnology Analysis
3.3. Technology ApplicationTechnology Application
4.4. Standard ReferenceStandard Reference
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Standard Reference
Bidirectional Forwarding Detection
draft-ietf-bfd-base-02
draft-ietf-bfd-base-03
BFD for IPv4 and IPv6 (Single Hop)
draft-ietf-bfd-v4v6-1hop-02
BFD for Multihop Paths
draft-ietf-bfd-multihop-02
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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Thank You
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