Trends in MPLS TE/FRR and QoS

Dave Wang, Ph.D.
WANDL, Inc.

Agenda

Overview of MPLS TE
Case Studies
 Trends
Overview of FRR
Case Studies
 Trends
Overview of QoS
Case Studies
 Trends


Questions

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 As MPLS continues to mature, morecarriers are beginning to use MPLSTE/FRR for improving real-time
applications and QoS for prioritizing IP
traffic. We will discuss ways in whichthese technologies are commonly used invarious practical situations.

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Before MPLS TE
 How do you solve congestion in a plain IPnetwork?

 Modify IGP metrics
 Not scalable

 Overprovision your network (set a thresholdand order additional bandwidth when reached) Poor bandwidth utilization
 Expensive

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Before MPLS TE (cont’d)•Modifying the IGP metric just moves the congestion elsewhere
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Case Study: Link Utilization

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MPLS Today
 MPLS VPN with IP CoS No ATM cell tax
 Easier for carrier’s to build a business case
 Dominant in Europe and Asia
 MPLS TE FRRprotection

 Shared Risk Link Groups (SRLG)
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MPLS TE Today•Traffic rebalanced without spending additional $$$ for BW.
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Routing for Layer 3 Traffic OSPF, ISIS, BGP4
 Forwarding Equivalence Classes
 Dijkstra Algorithms
 Influenced by LSP Tunnels
 New Shortest Path Tree

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Forwarding Equivalence Classes

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Forwarding Equivalence Classes

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Using TE
 End-to-End Traffic Matrix Collection
 Load Balancing without Equal Cost

Multiple Paths (ECMP) ECMP may not balance traffic in all cases

 Virtual Trunks
 CCC, AToM

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Industry Practices
 Fully meshed Tunnels
 With / without FRR per LSP protection
 With / without RSVP BW
 With / without color/affinity/admin group

 Dynamic versus Explicit Routes
 Primary and backup path computations for

explicit routes

 Advertise LSP in IGP
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Survey of FRR Implementations
 FRR is an enabler for TE Need TE to deploy FRR

 Link, Node, or LSP Protection
 Configure detour path to exclude SRLG Dynamic or Manual configuration of bypass

routes. Explicit routes needs maintenance Sometimes deployed with 0 Kbit/s tunnel
 BW not really checked Hybrid between best effort IP and SDH restoration

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Cisco TE/FRR Example!
interface Tunnel0
description HK->LA
ip unnumbered Loopback0
Notes:
no ip directed-broadcast
If priority is missing, the default is 7,7
tag-switching ip
If Autoroute announce missing, this is a private tunnel
tunnel destination 12.34.56.129
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng autoroute announce
tunnel mpls traffic-eng priority 3 3tunnel mpls traffic-eng bandwidth 1000
tunnel mpls traffic-eng path-option 1 explicit name hk2latunnel mpls traffic-eng path-option 5 dynamic
tunnel mpls traffic-eng record-routetunnel mpls traffic-eng load-share 1
tunnel mpls traffic-eng fast-reroute!
ip explicit-path name hk2la enable
exclude-address 12.34.56.78!

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Juniper TE/FRR Example
traffic-engineering shortcuts;
admin-groups {transit 1;
content 2;
voip 3;L2vpn 4;}label-switched-path HK2LA {to 12.34.56.78;
metric 430;
fast-reroute;primary path1 {bandwidth 125m;
no-decrement-ttl;
optimize-timer 300;}
priority 3 3;
adaptive;admin-group {include transit;exclude content;}}
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Notes:
if priority is missing, the default is 7,0Shortcut is same as Cisco's Autoroute announce

FRR Link Protection Modeling•Can see backup routes CHI-WDC-ATL-HOU-DAL•Not Facility Diverse
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FRR Modeling•Now have a backup route for LP that is link & facility diverse
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FRR detour Design Challenges
 Consider SRLG
 Bandwidth setting of FRR backup tunnels
 Difficult to protect 100 % of link BW

especially with tunnels already deployed.
Should focus on a subset of tunnels such as VoIP
 No need to protect all links with FRR. Some links could
be SONET protected so no need to protect them twice.
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FRR Design Challenges (cont’d) One Implementation
 Primary tunnels (to be protected) marked as fastreroute. If link is down and backup tunnel is
implemented on the link, then all primary tunnels
passing through the link are detoured.
 BW overlap of paths used by the FRR backup tunnels.
 If enough BW, configure backup tunnel BW to be >=primary tunnel bandwidth (on the link). Otherwise,tunnels may need to be configured with smaller BW.
Offline simulation is needed to insure "performance
impact" acceptable during failure.
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Deploying FRR
 Voice over IP (VoIP)
 Link/Node detours
 FRR sometimes used as a SONET/SDH “killer”
 Trying to remove a layer from the network

 Delay Sensitive video and voice
 Transit Service Provider

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IP Class Of Service
 Real life implementations: A few classes in the core (e.g. among Ps).
 Near real time (e.g. voice or video) Premium (e.g. top VPN customers)
 Best effort (basically everybody else) Possibly more class definition at the edge(e.g. PEs) but mapping is performed into
“core classes”

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IP Class Of Service (cont’d) Main advantages:
Easy to configure: does not require any signaling process
Based on straight forward packet tagging process (TOS,precedence,…) Limitations:

Not Proactive
Only used to decide who should be dropped during congestion

Works when average utilization is not highCopyright ©2003, WANDL, Inc.

Quality of Service (QoS)
 Use WFQ to differentiate 3-4 classes
 LLQ Voice First Class/Business Class Best Effort Class Extract MPLS tunnel traffic data in QoS
 SNMP does not yet report per QoS
 If tunnel sizing correct (can route/re-route)then QoS problem will not occur

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Quality of Service (QoS) cont’d Global Pool / SubPool RSVP BW partition
 SubPool used to be called guaranteedbandwidth traffic engineering SubPool Tunnel need to have high setup

and holding priority and high QoS

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Global Pool vs SubPool

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Quality of Service (QoS) cont’d Diffserv with MPLS TE
 L-LSP E-LSP Granularity versus Scalability
 No Hard commitment without bandwidthreservation
 Not yet popular.
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Quality of Service (QoS) cont’d Current solution is still to simply throw

bandwidth at the problem.
 Best solution is to configure LSP tunnel
bandwidth correctly.

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Multiple Vendor Environments
 Lab testing for Interoperability
 Use only compatible features
 Need vendor support to resolve issues

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Importance of Processes
 Calculate the worst case for each link andbuild in appropriate redundancies
 TE is very difficult to simulate manuallyand it is not intuitive Color logic and tunnel attributes
 Load balancing

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Importance of Processes(cont’d) Primary/backup path computation

 Verify QoS configuration
 Offline simulation of traffic growth Even with overprovisioning, traffic growth

may still surpass network capacity

 Multiple vendor network modeling Inventory management and reconciliation
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Capacity Planning Approaches
Point to point (e.g. End to End (widelyMRTG)
used in voice, ATM)PROVery easy to implement
Low upfront investment

troubleshoot congestion
Minimizes over-provisioningCONS

Can lead to poor design ifComplex to manage in aCopyright ©2003, WANDL, Inc.

the sources of traffic changeover time
May artificially increase
backbone filling ratio due totoo many hops

Accurate picture of traffic

connectionless environment

toIndustry Direction
 Convergence of IP/ATM/FR
 L3 MPLS
 L2/L3 VPN and TPLS FRR for Link/Node/LSP Protection
 TE acceptance will be driven by increaseddemand for bandwidth from high-speed
Internet access like DSL and Cable.

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Questions?

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