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© 2006 Cisco Systems, Inc. All rights reserved. Implementing Secure Converged Wide Area Networks (ISCW) Module 4: Frame Mode MPLS Implementation
© 2006 Cisco Systems, Inc. All rights reserved.
Implementing Secure Converged Wide Area Networks (ISCW)
Module 4: Frame Mode MPLS Implementation
© 2006 Cisco Systems, Inc. All rights reserved.
Module 4: Frame Mode MPLS Implementation
Lesson 4.3: Implementing Frame Mode MPLS
© 2006 Cisco Systems, Inc. All rights reserved.
Objectives Describe the steps required to configure MPLS.
Identify the distribution protocol options when configuring MPLS.
© 2006 Cisco Systems, Inc. All rights reserved.
The Procedure to Configure MPLS Configure CEF.
Configure MPLS on a frame mode interface.
(Optional) Configure the MTU size in label switching.
© 2006 Cisco Systems, Inc. All rights reserved.
Step 1: Configure CEF To enable MPLS, you must first configure CEF:
Configure CEF:Enable CEF switching to create the FIB table.Enable CEF switching on all core interfaces.
Configure MPLS on a frame mode interface.
(Optional) Configure the MTU size in label switching.
© 2006 Cisco Systems, Inc. All rights reserved.
ip cef [distributed]Router(config)#
Commands for Configuring CEF
Starts CEF switching and creates the FIB table
The distributed keyword configures distributed CEF (running on VIP or line cards)
All CEF-capable interfaces run CEF switching
ip route-cache cefRouter(config-if)#
Enables CEF switching on an interface
Usually not needed
© 2006 Cisco Systems, Inc. All rights reserved.
Using the ip cef [distributed] Parameter The optional [distributed] parameter enables
dCEF. This distributes the CEF information to the line cards and the line cards perform express forwarding.
Consider the following:CEF is enabled by default only on these platforms:
Cisco 7100 series routerCisco 7200 series routerCisco 7500 series Internet router
Distributed CEF is enabled on the Cisco 6500 series router.Distributed CEF is enabled on the Cisco 12000 series Internet router.
© 2006 Cisco Systems, Inc. All rights reserved.
Monitoring IP CEF
Displays a summary of the FIB
show ip cef detailRouter#
Router#show ip cef detailIP CEF with switching (Table Version 6), flags=0x0
6 routes, 0 reresolve, 0 unresolved (0 old, 0 new) 9 leaves, 11 nodes, 12556 bytes, 9 inserts, 0 invalidations 0 load sharing elements, 0 bytes, 0 references 2 CEF resets, 0 revisions of existing leaves refcounts: 543 leaf, 544 node
Adjacency Table has 4 adjacencies0.0.0.0/32, version 0, receive192.168.3.1/32, version 3, cached adjacency to Serial0/0.100 packets, 0 bytes tag information set local tag: 28 fast tag rewrite with Se0/0.10, point2point, tags imposed: {28} via 192.168.3.10, Serial0/0.10, 0 dependencies next hop 192.168.3.10, Serial0/0.10 valid cached adjacency tag rewrite with Se0/0.10, point2point, tags imposed: {28}
© 2006 Cisco Systems, Inc. All rights reserved.
Using show ip cef ParametersParameter Description
Unresolved (Optional) Displays unresolved FIB entries
Summary (Optional) Displays a summary of the FIB
Network (Optional) Displays the FIB entry for the specified destination network
Mask (Optional) Displays the FIB entry for the specified destination network and mask
Longer-prefixes
(Optional) Displays the FIB entries for all the specific destinations
Detail (Optional) Displays detailed FIB entry information
type number (Optional) Lists the interface type and number for which to display FIB entries
© 2006 Cisco Systems, Inc. All rights reserved.
Step 2: Configure MPLS on Frame Mode Interface Configure CEF.
Configure MPLS on a frame mode interface:Enable label switching on a frame mode interface.Start LDP or TDP label distribution protocol.
(Optional) Configure the MTU size in label switching.
© 2006 Cisco Systems, Inc. All rights reserved.
Commands for Configuring MPLS on a Frame Mode Interface
Enables label switching on a frame mode interface
Starts LDP on the interface
mpls ipRouter(config-if)#
mpls label protocol [tdp | ldp | both]Router(config-if)#
Starts selected label distribution protocol on the specified interface
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Configuring MPLS on a Frame Mode Interface: Example 1
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Configuring MPLS on a Frame Mode Interface: Example 2
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Step 3: Configure the MTU Size in Label Switching Configure CEF.
Configure MPLS on a frame mode interface.
Configure the MTU size in label switching:Increase MTU on LAN interfaces.
© 2006 Cisco Systems, Inc. All rights reserved.
Commands for Configuring MTU Size
Label switching increases the MTU requirements on an interface because of additional label header.
Interface MTU is automatically increased on WAN interfaces; IP MTU is automatically decreased on LAN interfaces.
Label-switching MTU can be increased on LAN interfaces (resulting in jumbo frames) to prevent IP fragmentation.
mpls mtu bytesRouter(config-if)#
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Configuring Label Switching MTU
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Summary There are three steps to configuring an MPLS:
Configure CEF:.Configure MPLS on a frame mode interface.Configure the maximum transmission unit (MTU) size in label switching.
To enable MPLS, you must first enable CEF switching. CEF switching is commonly enabled globally on a router. However, it can also be enabled on individual interfaces.
You can display entries in the FIB or display a summary of the FIB with the show ip cef command.
Cisco routers can use one or both of two protocols for distribution:Tag Distribution Protocol (TDP)Label Distribution Protocol (LDP)
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Q and A
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Resources Multiprotocol Label Switching (MPLS)
http://www.cisco.com/en/US/partner/tech/tk436/tsd_technology_support_category_home.html
© 2006 Cisco Systems, Inc. All rights reserved.
