-
null
The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
The purpose of this document is to describe the changes based on the Cisco Express Forwarding infrastructure scalability enhancements that have been implemented to adapt to the evolution of the Internet and to support new platforms and features. The changes are the removal of IP fast switching and the introduction of command line interface (CLI) modifications.
This document lists Cisco Express Forwarding CLI commands that are removed, replaced, changed, and new. To help you transition to the new CLI format, the document illustrates the output for new commands and changed commands.
Enhancements to Cisco Express Forwarding enable it to operate with the Multiprotocol Label Switching (MPLS) Forwarding Infrastructure (MFI) and guarantee consistency across Cisco IOS release trains. Cisco Express Forwarding infrastructure changes were introduced and implemented in the Cisco IOS 12.2(25)S-based releases and were added for T releases in Cisco IOS Release 12.4(20)T.
Cisco Express Forwarding is an advanced Layer 3 IP switching technology. It optimizes network performance and scalability for all kinds of networks: those that carry small amounts of traffic and those that carry large amounts of traffic in complex patterns, such as the Internet, and networks characterized by intensive web-based applications or interactive sessions.
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Cisco Express Forwarding" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
•Information About Cisco Express Forwarding
•Feature Information for Cisco Express Forwarding
This document presents the following topics to explain the changes you will find with the implementation of the Cisco Express Forwarding enhancements. This information should be helpful as you transition to Cisco IOS software that includes the Cisco Express Forwarding and MFI enhancements.
•Introduction of Cisco Express Forwarding Enhancements
•Cisco Express Forwarding Enhancements Described
•Removal of Support for IPv4 Fast Switching
•Removed, Obsolete, and No Longer Supported Cisco Express Forwarding Commands
•Cisco Express Forwarding CLI Command Output Changes
•New Commands for the Cisco Express Forwarding Feature
•Unchanged Cisco Express Forwarding show Commands
The fifth and sixth topics provide information about the CLI changes implemented as part of the Cisco Express Forwarding enhancements. In each section, the commands that are changed are listed, followed by an explanation of how they are changed. Sample command output is included in sections to compare "before" and "after" output information and to provide new output information.
The information about the commands is presented in the following order:
•Removed or existing, but unsupported, commands
•Commands with modified output
•New commands created for output consistency
•Related commands with unchanged output
Cisco Express Forwarding is at the heart of switching in every router. Improvements have been made to the Cisco Express Forwarding infrastructure to enhance and scale switching. Cisco Express Forwarding enhancements were introduced in Cisco IOS Release 12.2(25)S and first adopted by Cisco IOS 12.2(25)S-based releases. In Cisco IOS Release 12.4(20)T, the Cisco Express Forwarding enhancements were added for Cisco IOS 12.4(20)T releases and later T-based releases.
Table 1 lists the Cisco IOS releases and platforms that support the Cisco Express Forwarding enhancements and the changes described in this document.
Cisco IOS Release 12.4(20)T incorporates the following Cisco Express Forwarding infrastructure changes:
•Cisco Express Forwarding Scalability and Selective Rewrite (CSSR) for enhanced scalable, distributed Layer 3 switching
•Enhanced Multiprotocol Label Switching (MPLS) Forwarding Infrastructure (MFI)
For information on MFI enhancements, see MPLS Infrastructure Changes: Introduction of MFI and Removal of MPLS LSC and LC-ATM Features.
The Cisco Express Forwarding infrastructure changes provide the following:
•Simplified fast switching path decisions for both IPv4 and IPv6 traffic, which improve performance and provide more CPU cycles for other Cisco IOS services
•Enhanced scalability to support large numbers of the following:
–IPv4 and IPv6 prefixes and adjacencies
–Load balancing paths over multiple links based on Layer 3 routing information
–Virtual Private Network (VPN) routing and forwarding (VRF) instances
•Improved manageability of the following:
–Cisco Express Forwarding logging for both IPv4 and IPv6
–Unicast Reverse Path Forwarding (uRPF) strict and loose mode
–Cisco Express Forwarding MIB (CEF-MIB)
–uRPF MIB
–CLI display enhancements for Cisco Express Forwarding
No new features are introduced in Cisco IOS Release 12.4(20)T. However, some features that previously shipped with a Cisco IOS 12.2(25)S-based release are new to the Cisco IOS 12.4T release.
Note CSSR and MFI enhancements in Cisco IOS Release 12.4(20)T might result in changed performance characteristics in your network. We suggest that you test configurations before upgrading to this software.
IPv4 fast switching is removed with the implementation of the Cisco Express Forwarding infrastructure enhancements for Cisco IOS 12.2(25)S-based releases and Cisco IOS Release 12.4(20)T. For these and later Cisco IOS releases, switching path are Cisco Express Forwarding switched or process switched. This makes the switching decision easier for future development of software features.
Note Starting with the implementation of the Cisco Express Forwarding enhancements and the removal of IPv4 fast switching, components that do not support Cisco Express Forwarding will work only in process switched mode.
The following commands are obsolete and have been removed from Cisco IOS software with the present Cisco Express Forwarding enhancements:
•show ip cef inconsistency records
•show ip cef inconsistency now
•show ip cef inconsistency now detail
Table 2 lists the commands that replace the removed commands.
The following commands still exist, but are no longer supported in Cisco IOS software:
•show cef events
•show cef dropped
•show cef non-cef-switched
Table 3 lists commands that still exist, but are no longer supported, and the commands that replaces the unsupported commands. You should start using the replacement commands.
|
|
---|---|
ip cef event -log |
monitor event-log cef event |
ip cef interface event-log |
monitor event-log cef interface |
ip cef table event-log |
monitor event-log cef ipv4 |
ip cef table consistency-check |
cef table consistency-check |
ip cef loadinfo |
cef table output-chain |
show cef events |
show monitor event-trace cef events all |
show cef drop |
show {ip | ipv6} cef switching statistics [feature]1 |
show cef not-cef-switched |
show {ip | ipv6} cef switching statistics [feature] |
1 If you enter the optional feature keyword, the output shows per-feature drop and punt counters. |
This section describes the CLI command output changes introduced with the Cisco Express Forwarding feature. In some commands the output format is changed. In other commands, pieces of information are added or removed from the output. The output of the following commands is changed with this feature:
•show ip cef <prefix> internal
•show ipv6 cef <prefix> internal
•show ip cef exact-route <source> <destination> detail
•show ip cef exact-route <source> <destination>
•show ip cef adjacency <interface> <next-hop>
•show ip cef unresolved detail
•show ipv6 cef unresolved detail
For a full description of these commands, see the Cisco IOS IP Switching Command Reference and the Cisco IOS IPv6 Command Reference.
This feature provides the following changes to the output of the show ip cef summary command:
•IPv4 and IPv6 are separately addressed.
•Figures related to adjacencies are moved to the show adjacency summary command (see the "show adjacency summary" section).
•Mtrie data structure descriptions are moved to a new command, the show ip cef tree command (see the "New Commands for the Cisco Express Forwarding Feature" section).
Table 4 compares the show ip cef summary command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show ipv6 cef summary command:
•Output is reformatted (information provided is similar to what was provided before the Cisco Express Forwarding enhancement.)
Table 5 compares the show ipv6 cef summary command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show ip cef internal command:
•IPv4 and IPv6 are separately addressed.
•Mtrie data structure descriptions are moved to a new command, the show ip cef tree command (see the "New Commands for the Cisco Express Forwarding Feature" section).
•Troubleshooting is made easier with the addition of references to internal structure pointers.
•The concept of output chain (chain of output features) is introduced.
Table 6 compares the show ip cef internal command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show ipv6 cef internal command:
•More references to pointers are added.
•The concept of output chain (chain of output features) is introduced.
The previous version of the command output is very similar to the output of the command after the Cisco Express Forwarding enhancements.
Table 7 compares the show ipv6 cef internal command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show ip cef detail command:
•IPv4 and IPv6 are now separately addressed.
•Mtrie data structure descriptions are moved to a new command, the show ip cef tree command (see the "New Commands for the Cisco Express Forwarding Feature" section).
•The per-prefix output is reformatted (however, the information provided is the same).
•Table 8 compares the show ip cef detail command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show ipv6 cef detail command:
•Output is reformatted (the information provided is the same as before the Cisco Express Forwarding enhancements).
Table 9 compares the show ipv6 cef detail command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show ip cef prefix internal command:
•Troubleshooting is made easier with the addition of references to internal structure pointers.
•The concept of output chain (chain of output features) is introduced.
Table 10 compares the show ip cef prefix internal command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show ipv6 cef prefix internal command:
•More references to structure pointers are added.
•The concept of output chain (chain of output features) is introduced.
The previous version of the command output is very similar to the output in the command after the Cisco Express Forwarding enhancements.
Table 11 compares the show ipv6 cef prefix internal command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show ip cef prefix command:
•Output is reformatted; the key information provided is similar to the command output provided before the Cisco Express Forwarding enhancements.
•Adjacency information is moved to the show adjacency prefix detail command (see the "New Commands for the Cisco Express Forwarding Feature" section).
Table 12 compares the show ip cef prefix command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
Note The command output of the show ipv6 prefix command is the same after the Cisco Express Forwarding enhancement changes as it was before the changes.
This feature provides the following change to the output of the show ip cef exact-route source destination detail command:
•Output is reformatted (the information provided is the same as the information provided before the Cisco Express Forwarding enhancements).
Table 13 compares the command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show ip cef exact-route source destination command:
•Output is reformatted (the information provided is the same as the information provided before the Cisco Express Forwarding enhancements).
Table 14 compares the show ip cef exact-route source destination command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show ip cef adjacency interface next-hop command:
•Output is reformatted (the information provided is the same as the information provided before the Cisco Express Forwarding enhancements).
Table 15 compares the show ip cef adjacency interface next-hop command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show adjacency summary command:
•The new output provides a detailed description of the database, high availability information, and epoch concept information.
•The per-protocol and interface summary table is moved to the show adjacency link command (see the "New Commands for the Cisco Express Forwarding Feature" section).
Table 16 compares the show adjacency summary command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show adjacency detail command:
•Output is reformatted (the information provided is the same as the information provided before the Cisco Express Forwarding enhancements).
Table 17 compares the show adjacency detail command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show adjacency internal command:
•Output is reformatted.
•An output chain of features was added. Otherwise, the information provided is the same as the information provided before the Cisco Express Forwarding enhancements.
Table 18 compares the show adjacency internal command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show cef state command:
•New output is more concise.
•Load sharing anti-polarization ID is added to the command output.
•The show cef state command adds a new capabilities keyword. Capability details now display with the new keyword.
Table 19 compares the show cef state command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
|
|
---|---|
Router# show cef state CEF Status [RP] CEF enabled/running dCEF disabled/not running CEF switching enabled/running CEF default capabilities: Always CEF switching: no Always dCEF switching: no Default CEF switching: yes Default dCEF switching: no Drop multicast packets: no OK to punt packets: yes NVGEN CEF state: no fastsend() used: yes CEF NSF capable: no RPR+/SSO standby capable: no IPC delayed func on SSO: no FIB auto repair supported: yes LCs not running at init time: no Hardware forwarding supported: no Hardware forwarding in use: no Load-sharing pr. packet supported: yes |
Router# show cef state CEF Status: RP instance common CEF enabled IPv4 CEF Status: CEF enabled/running dCEF disabled/not running CEF switching enabled/running universal per-destination load sharing algorithm, id A189DD49 IPv6 CEF Status: CEF enabled/running dCEF disabled/not running original per-destination load sharing algorithm, id A189DD49 Router# show cef state capabilities CEF Capabilities: Supported address families: IPv4 IPv6 Active address families: IPv4 IPv6 Distributed Platform: no Warm or Hot Standby supported: no CEF NSF capable: no IPC delayed func on SSO: no Hardware forwarding: no Checker auto-repair supported: yes Crashdump on memory failure: no Support load-sharing alg config: yes Blocking STANDBY_HOT until synced: no IPv4 CEF Capabilities: Default CEF switching: yes Always FIB switching: no Default dCEF switching: no Always dCEF switching: no Drop multicast packets: no OK to punt packets: yes NVGEN CEF state: yes fastsend() used: yes Support per packet load sharing: yes Support L4 ports in load sharing: yes Multicast (*,G) groups in CEF: no Install local entries from RIB: no |
|
IPv6 CEF Capabilities:1 Default CEF switching: yes Always FIB switching: no Default dCEF switching: no Always dFIB switching: no Drop multicast packets: no OK to punt packets: yes NVGEN CEF state: yes fastsend() used: yes L4 ports in load balancing support: yes |
1 This is the continuation of the output of the show cef state capabilities command. |
This feature provides the following change to the output of the show cef timers command:
•The command output has been updated to reflect the new timers.
Table 20 compares the show cef timers command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show ip cef epoch command:
•Adjacency epoch information is removed and is available from the show adjacency summary command (see the"New Commands for the Cisco Express Forwarding Feature" section).
Table 21 compares the show ip cef epoch command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show ipv6 cef epoch command:
•Adjacency epoch information is removed and is available from the show adjacency summary command (see the "New Commands for the Cisco Express Forwarding Feature" section).
Table 22 compares the show ipv6 cef epoch command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show ip cef unresolved detail command:
•The new command output lists only unresolved prefixes.
•IPv4 and IPv6 are now separately addressed.
•Figures related to adjacencies are moved to the show adjacency summary command (see the "show adjacency summary" section).
•Mtrie data structure descriptions are moved to a new command, the show ip cef tree command (see the "New Commands for the Cisco Express Forwarding Feature" section).
•Nothing is displayed if no unresolved adjacencies exist.
Table 23 compares the show ip cef unresolved detail command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following changes to the output of the show ipv6 cef unresolved detail command:
•Figures related to adjacencies are moved to the show adjacency summary command (see the "show adjacency summary" section).
•Nothing is displayed in the output if there are no unresolved adjacencies.
Table 24 compares the show ipv6 cef unresolved detail command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This feature provides the following change to the output of the show ipv6 cef non-recursive command:
•The path information is changed to be more consistent with IPv4 path information.
Table 25 compares the show ipv6 cef non-recursive command output before ("Old" heading) and after ("New" heading) the Cisco Express Forwarding enhancements.
This section does not contain all new Cisco Express Forwarding commands. It contains only new commands introduced with the Cisco Express Forwarding enhancements to provide the same level of information that was available with the use of other commands before the Cisco Express Forwarding enhancements were implemented. Sample output is provided for the following new commands:
•show adjacency link {ipv4 | ipv6}
•show adjacency <prefix> detail
•test cef table consistency detail
The show adjacency link ipv4 command and the show adjacency link ipv6 command display information about IPv4 and IPv6 traffic, respectively, in the Cisco Express Forwarding adjacency table or the hardware Layer 3-switching adjacency table.
Per-protocol and interface summary adjacency information was moved from the show adjacency summary command to the show adjacency link command.
Following is sample output of the show adjacency link ipv4 command.
Router# show adjacency link ipv4
Protocol Interface Address
IP FastEthernet0/0 10.60.17.2(6)
IP FastEthernet0/0 10.60.17.20(6)
IP FastEthernet0/0 10.60.17.254(7)
IP FastEthernet0/1 172.17.22.1(16)
Following is sample output of the show adjacency link ipv6 command.
Router# show adjacency link ipv6
Protocol Interface Address
IPV6 FastEthernet0/1 2001:2:22::1(6)
IPV6 FastEthernet0/1 2001:2:22::2(3) (incomplete)
IPV6 FastEthernet0/1 FE80::2D0:1FF:FEE4:6800(14)
IPV6 Serial3/0 point2point(7)
IPV6 Serial3/1 point2point(10
The show adjacency prefix command shows adjacency information for the specified prefix.
Following are sample outputs from the show adjacency prefix command for an IPv4 prefix and an IPv6 prefix:
Router# show adjacency 172.17.22.1/24
Protocol Interface Address
IP FastEthernet0/1 172.17.22.1(16)
Router# show adjacency 2001:2:22::1/64
Protocol Interface Address
IPV6 FastEthernet0/1 2001:2:22::1(6)
The show adjacency prefix detail command provides additional adjacency information for a specified prefix.
Information about the adjacency epoch was removed from the show ip cef epoch and show ipv6 cef epoch commands and is available from the show adjacency prefix detail command.
Following are sample outputs from the show adjacency prefix detail command for an IPv4 prefix and an IPv6 prefix:
Router# show adjacency 172.17.22.1/24 detail
Protocol Interface Address
IP FastEthernet0/1 172.17.22.1(16)
0 packets, 0 bytes
epoch 0
sourced in sev-epoch 3
Encap length 14
00D001E4680000055FAF2C060800
ARP
Router# show adjacency 2001:2:22::1/64 detail
Protocol Interface Address
IPV6 FastEthernet0/1 2001:2:22::1(6)
0 packets, 0 bytes
epoch 0
sourced in sev-epoch 3
Encap length 14
00D001E4680000055FAF2C0686DD
IPv6 ND
The show {ip | ipv6} cef tree command displays summary information about the underlying data structures representing the specified FIB tree.
Mtrie data structure information was removed from several commands for the implementation of the Cisco Express Forwarding enhancements. This command provides the Mtrie information removed from the show ip cef summary, show ip cef internal, and show ip cef detail commands.
Following is sample output for the show ip cef tree command:
Router# show ip cef tree
VRF Default tree information:
MTRIE/RTREE storing IPv4 addresses
24 entries (24/0 fwd/non-fwd)
Forwarding tree:
Forwarding lookup routine: IPv4 mtrie 8-8-8-8 optimized
33 inserts, 9 deletes
8-8-8-8 stride pattern
short mask protection enabled for <= 4 bits without process suspension
24 leaves (672 bytes), 22 nodes (22880 bytes)
25208 total bytes
leaf ops: 33 inserts, 9 deletes
leaf ops with short mask protection: 2 inserts, 1 delete
per-prefix length stats: lookup off, insert off, delete off
refcounts: 1356 leaf, 1324 node
node pools:
pool[C/8 bits]: 22 allocated (0 failed), 22880 bytes
Non-Forwarding tree:
38 inserts, 38 deletes
0 leaves (0 bytes), 0 nodes (0 bytes)
0 total bytes
The test cef table consistency detail command displays recorded Cisco Express Forwarding consistency records found by the following detection mechanisms: lc-detect, scan-rib-ios, scan-ios-rib, scan-lc-rp, and scan-rp-lc. The scan-lc-rp and scan-rp-lc detection mechanisms are available only on routers with line cards. You can configure the Cisco Express Forwarding prefix consistency-detection mechanisms using the cef table consistency-check command.
This command provides output that replaces the output provided by the removed and obsolete show ip cef inconsistency records, show ip cef inconsistency now, and show ip cef inconsistency now detail commands.
Following is sample output for the test cef table consistency detail command:
Router# test cef table consistency detail
full-scan-rib-ios: Checking IPv4 RIB to FIB consistency
full-scan-rib-ios: FIB checked 12 prefixes, and found 0 missing.
full-scan-ios-rib: Checking IPv4 FIB to RIB consistency
full-scan-ios-rib: Checked 12 FIB prefixes in 1 pass, and found 0 extra.
full-scan-rp-lc: Sent 26 IPv4 prefixes to linecards in 1 pass
full-scan-rp-lc: Initiated IPv4 FIB check on linecards..4..1..0..
full-scan-rp-lc: FIB IPv4 check completed on linecards..1..0..4..
full-scan-rp-lc: Linecard 4 checked 26 IPv4 prefixes (ignored 0). 0 inconsistent.
full-scan-rp-lc: Linecard 1 checked 26 IPv4 prefixes (ignored 0). 0 inconsistent.
full-scan-rp-lc: Linecard 0 checked 26 IPv4 prefixes (ignored 0). 0 inconsistent.
full-scan-rib-ios: Checking IPv6 RIB to FIB consistency
full-scan-rib-ios: FIB checked 16 prefixes, and found 5 missing.
full-scan-ios-rib: Checking IPv6 FIB to RIB consistency
full-scan-ios-rib: Checked 11 FIB prefixes in 1 pass, and found 0 extra.
full-scan-rp-lc: Sent 11 IPv6 prefixes to linecards in 1 pass
full-scan-rp-lc: Initiated IPv6 FIB check on linecards..4..1..0..
full-scan-rp-lc: FIB IPv6 check completed on linecards..1..4..0..
full-scan-rp-lc: Linecard 4 checked 11 IPv6 prefixes (ignored 0). 0 inconsistent.
full-scan-rp-lc: Linecard 1 checked 11 IPv6 prefixes (ignored 0). 0 inconsistent.
full-scan-rp-lc: Linecard 0 checked 11 IPv6 prefixes (ignored 0). 0 inconsistent.
No IPv4 inconsistencies found, check took 00:00:01.444
Warning: 5 IPv6 inconsistencies found, check took 00:00:01.240
Some Cisco Express Forwarding show commands related to the Cisco Express Forwarding enhancements were not changed with the introduction of the enhancements. The output of the following commands was not changed:
•show cef idb
•show cef interface
•show ip cef
•show ip cef non-recursive
•show ipv6 cef
•show ipv6 cef adjacency
|
|
---|---|
Cisco IOS commands |
|
Description of Cisco Express Forwarding commands |
|
Description of Cisco Express Forwarding IPv6 commands |
|
Information on MFI enhancements |
MPLS Infrastructure Changes: Introduction of MFI and Removal of MPLS LSC and LC-ATM Features |
Table 26 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 26 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
adjacency—A relationship formed between selected neighboring routers and end nodes for the purpose of exchanging routing information. Adjacency is based upon the use of a common media segment by the routers and nodes involved.
Cisco Express Forwarding—A Layer 3 switching technology. Cisco Express Forwarding can also refer to central Cisco Express Forwarding mode, one of two modes of Cisco Express Forwarding operation. Cisco Express Forwarding enables a Route Processor (RP) to perform express forwarding. Distributed Cisco Express Forwarding is the other mode of Cisco Express Forwarding operation.
distributed Cisco Express Forwarding—A type of Cisco Express Forwarding switching in which line cards (such as Versatile Interface Processor (VIP) line cards) maintain identical copies of the forwarding information base (FIB) and adjacency tables. The line cards perform the express forwarding between port adapters; this relieves the Route Switch Processor of involvement in the switching operation.
FIB—forwarding information base. A component of Cisco Express Forwarding. The router uses the FIB lookup table to make destination-based switching decisions during Cisco Express Forwarding operation. The router maintains a mirror image of the forwarding information in an IP routing table.
IDB—Interface Descriptor Block. An IDB is a special control structure internal to the Cisco IOS software that contains information such as the IP address, interface state, and packet statistics. Cisco IOS software maintains one IDB for each interface present on a platform and one IDB for each subinterface.
IPRM—IP Rewrite Manager. The IPRM is a module that manages the interaction between Cisco Express Forwarding, the IP Label Distributions Modules (LDM), and the Multiprotocol Label Switching (MPLS) Forwarding Infrastructure (MFI).
Mtrie—multiway tree. The Mtrie is a data structure in which routes are stored. The Mtrie is part of the IP lookup algorithm used in Cisco Express Forwarding.
prefix—The network address portion of an IP address. A prefix is specified by a network and mask and is generally represented in the format network/mask. The mask indicates which bits are the network bits. For example, 10.0.0.0/16 means that the first 16 bits of the IP address are masked, making them the network bits. The remaining bits are the host bits. In this example, the network number is 10.0.
RIB—Routing Information Base. A central repository of routes that contains Layer 3 reachability information and destination IP addresses or prefixes. The RIB is also known as the routing table.
RP—Route Processor. The processor module in the Cisco 7000 series routers that contains the CPU, system software, and most of the memory components that are used in the router. It is sometimes called a supervisory processor.
VRF—A Virtual Private Network (VPN) routing/forwarding instance. A VRF consists of an IP routing table, a derived forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing protocols that determine what goes into the forwarding table. In general, a VRF includes the routing information that defines a customer VPN site that is attached to a provider edge (PE) router.