Cisco NX-OS/IOS BGP (Basic) Comparison

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(New page: <font size = "3">'''Objective'''</font> This''' '''tech note outlines the main differences in Border Gateway Protocol support between Cisco® NX-OS Software and Cisco IOS® Software. Sa...)
 
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<font size = "3">'''Important Cisco NX-OS and Cisco IOS Softfware Differences'''</font>
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<font size = "3">'''Important Cisco NX-OS and Cisco IOS Software Differences'''</font>
In Cisco NX-OS:
In Cisco NX-OS:
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* BGP CLI configuration and verification commands are not available until you enable the BGP feature via the '''feature bgp''' command.
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* BGP CLI configuration and verification commands are not available until you enable the BGP feature with the '''feature bgp''' command.
-
* The BGP protocol requires the Enterprise Services license.
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* The BGP protocol requires an Enterprise Services license.
-
* Autonomous Numbers can be configured as 16 or 32 bit values.
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* Autonomous system numbers can be configured as 16 or 32 bit values.
-
* Address families need to be explicitly enabled (IE: IPv4 unicast, IPv6 unicast, etc…)
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* Address families need to be explicitly enabled (IE: IPv4 unicast, IPv6 unicast, etc…).  All address families are disabled by default.
* By default, eBGP supports 8 Equal Cost Paths and iBGP supports 1.  The Cisco NX-OS supports up to 16 Equal Cost Paths for both eBGP and iBGP.
* By default, eBGP supports 8 Equal Cost Paths and iBGP supports 1.  The Cisco NX-OS supports up to 16 Equal Cost Paths for both eBGP and iBGP.
* Automatic Route Summarization and Synchronization are disabled by default.
* Automatic Route Summarization and Synchronization are disabled by default.
* BGP consists of a hierarchical configuration based on neighbors and address families.
* BGP consists of a hierarchical configuration based on neighbors and address families.
* If a router ID is not manually configured, the loopback 0 IP address is always preferred. If loopback 0 does not exist, Cisco NX-OS selects the IP address for the first loopback interface in the configuration. If no loopback interfaces exist, Cisco NX-OS selects the IP address for the first physical interface in the configuration.
* If a router ID is not manually configured, the loopback 0 IP address is always preferred. If loopback 0 does not exist, Cisco NX-OS selects the IP address for the first loopback interface in the configuration. If no loopback interfaces exist, Cisco NX-OS selects the IP address for the first physical interface in the configuration.
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* Neighbor logging is not enabled by default under the BGP instance.
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* Neighbor logging is not enabled by default under the BGP instance.  Neighbor logging can be enabled with the '''log-neighbor-changes''' command.
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* When neighbor authentication is configured, the BGP key is 3DES encrypted in the configuration. Cisco IOS Software requires the '''service password''' command.
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* When neighbor authentication is configured, the BGP key is 3DES encrypted in the configuration. Cisco IOS Software requires the '''service password''' command to encrypt the password in the configuration.
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* One BGP instances can be created per Virtual Device Context (VDC).
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* One BGP instances can be configured per Virtual Device Context (VDC).
* Numerous Virtual Route Forwarding (VRF) instances can be associated to a BGP instance.
* Numerous Virtual Route Forwarding (VRF) instances can be associated to a BGP instance.
* If the '''feature bgp''' command is removed, all relevant BGP configuration information is also removed.
* If the '''feature bgp''' command is removed, all relevant BGP configuration information is also removed.
* Network statements must be configured under their respective address-family configuration mode when advertising them via BGP.
* Network statements must be configured under their respective address-family configuration mode when advertising them via BGP.
* The '''shutdown''' command under the BGP instance can be used to disable BGP while retaining the configuration.
* The '''shutdown''' command under the BGP instance can be used to disable BGP while retaining the configuration.
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* The '''show running-config''' bgp command displays the current BGP configuration.
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* The '''show running-config bgp''' command displays the current BGP configuration.
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* A BGP instance can be restarted with the '''restart bgp ''' ''<instance #>'' command.
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* A BGP instance can be restarted with the '''restart bgp ''<instance #>'' ''' command.
* Graceful Restart (RFC 3623) is enabled by default.
* Graceful Restart (RFC 3623) is enabled by default.
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{| border="1" cellpadding="2"
{| border="1" cellpadding="2"
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!width="225" align="left" style="background:#99CCFF;" |'''Cisco NX-OS BGP'''
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!width="270" align="left" style="background:#99CCFF;" |'''Cisco NX-OS BGP'''
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!width="225" align="left" style="background:#99CCFF;" |'''Cisco IOS Software BGP'''
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!width="270" align="left" style="background:#99CCFF;" |'''Cisco IOS Software BGP'''
!width="450" align="left" style="background:#99CCFF;" |'''Command Description'''
!width="450" align="left" style="background:#99CCFF;" |'''Command Description'''
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|-
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|'''show bgp convergence || - || Displays global convergence information
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|-
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|'''show bgp process || - || Displays global BGP process information
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|-
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|'''show bgp sessions || - || Displays information for all neighbors
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|-
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|'''show bgp statistics || - || Displays global BGP process statistics
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|-
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| <font color="white"> - || <font color="white"> - || <font color="white"> -
|-
|-
|'''show ip bgp''' ''<option>''|| show ip bgp || Displays BGP Process and BGP table entries
|'''show ip bgp''' ''<option>''|| show ip bgp || Displays BGP Process and BGP table entries
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|-
|-
|'''show ip bgp community no-export-spoofed'''|| - || Displays BGP routes not sent to outside local AS
|'''show ip bgp community no-export-spoofed'''|| - || Displays BGP routes not sent to outside local AS
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|-
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|<b>show ip bgp community-list</b> <i><name></i>|| show ip bgp community-list <i><name></i> || Displays a specific BGP community list
|-
|-
|'''show ip bgp dampening dampened-paths'''|| show ip bgp dampening dampened-paths || Displays all Dampened paths
|'''show ip bgp dampening dampened-paths'''|| show ip bgp dampening dampened-paths || Displays all Dampened paths
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|-
|-
|'''show ip bgp dampening parameters'''|| show ip bgp dampening parameters || Displays all of the Dampening parameters
|'''show ip bgp dampening parameters'''|| show ip bgp dampening parameters || Displays all of the Dampening parameters
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|-
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|'''show ip bgp extcommunity''' ''<word>''|| - || Displays routes with a specific regular expression for extended communities
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|-
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|'''show ip bgp extcommunity-list''' ''<name>''|| - || Displays a specific BGP extended community list
|-
|-
|'''show ip bgp filter-list'''|| show ip bgp filter-list || Displays all routes matching a specified filter list
|'''show ip bgp filter-list'''|| show ip bgp filter-list || Displays all routes matching a specified filter list
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|'''show ip bgp neighbors''' ''x.x.x.x''|| show ip bgp neighbors ''x.x.x.x'' || Displays detailed information for a neighbor
|'''show ip bgp neighbors''' ''x.x.x.x''|| show ip bgp neighbors ''x.x.x.x'' || Displays detailed information for a neighbor
|-
|-
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|'''show ip bgp nexhop ''' ''x.x.x.x''|| - || Displays all routes matching a specified next-hop
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|'''show ip bgp nexthop ''' ''x.x.x.x''|| - || Displays all routes matching a specified next-hop
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|-
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|'''show ip bgp nexthop-database''' || - || Displays the next-hop database
|-
|-
|'''show ip bgp paths'''|| show ip bgp paths || Displays all BGP paths
|'''show ip bgp paths'''|| show ip bgp paths || Displays all BGP paths
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|-
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|'''show ip bgp regexp'''|| show ip bgp regexp || Displays routes matching a regular-expression
|'''show ip bgp regexp'''|| show ip bgp regexp || Displays routes matching a regular-expression
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|-
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|'''show ip bgp received-paths'''|| - || Displays the paths stored for soft reconfiguration
|-
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|'''show ip bgp route-map'''|| show ip bgp route-map || Displays BGP routes matching a route-map
|'''show ip bgp route-map'''|| show ip bgp route-map || Displays BGP routes matching a route-map

Latest revision as of 00:03, 23 January 2011

Objective

This tech note outlines the main differences in Border Gateway Protocol support between Cisco® NX-OS Software and Cisco IOS® Software. Sample configurations are included for the Cisco NX-OS and Cisco IOS Software for some common features to demonstrate the similarities and differences. Please refer to the NX-OS documentation on Cisco.com for a complete list of supported features.


BGP Overview

BGPv4 is a standard Exterior Routing Protocol defined in RFC 4271, commonly used to exchange network reachability information between autonomous systems. This document covers the features required for basic connectivity.


Important Cisco NX-OS and Cisco IOS Software Differences

In Cisco NX-OS:

  • BGP CLI configuration and verification commands are not available until you enable the BGP feature with the feature bgp command.
  • The BGP protocol requires an Enterprise Services license.
  • Autonomous system numbers can be configured as 16 or 32 bit values.
  • Address families need to be explicitly enabled (IE: IPv4 unicast, IPv6 unicast, etc…). All address families are disabled by default.
  • By default, eBGP supports 8 Equal Cost Paths and iBGP supports 1. The Cisco NX-OS supports up to 16 Equal Cost Paths for both eBGP and iBGP.
  • Automatic Route Summarization and Synchronization are disabled by default.
  • BGP consists of a hierarchical configuration based on neighbors and address families.
  • If a router ID is not manually configured, the loopback 0 IP address is always preferred. If loopback 0 does not exist, Cisco NX-OS selects the IP address for the first loopback interface in the configuration. If no loopback interfaces exist, Cisco NX-OS selects the IP address for the first physical interface in the configuration.
  • Neighbor logging is not enabled by default under the BGP instance. Neighbor logging can be enabled with the log-neighbor-changes command.
  • When neighbor authentication is configured, the BGP key is 3DES encrypted in the configuration. Cisco IOS Software requires the service password command to encrypt the password in the configuration.


Things You Should Know

The following list provides some additional facts about Cisco NX-OS that should be helpful when designing, configuring, and maintaining a BGP network.


  • One BGP instances can be configured per Virtual Device Context (VDC).
  • Numerous Virtual Route Forwarding (VRF) instances can be associated to a BGP instance.
  • If the feature bgp command is removed, all relevant BGP configuration information is also removed.
  • Network statements must be configured under their respective address-family configuration mode when advertising them via BGP.
  • The shutdown command under the BGP instance can be used to disable BGP while retaining the configuration.
  • The show running-config bgp command displays the current BGP configuration.
  • A BGP instance can be restarted with the restart bgp <instance #> command.
  • Graceful Restart (RFC 3623) is enabled by default.


Configuration Comparison

The following sample configuration code similarities and differences between the Cisco NX-OS and Cisco IOS Software CLIs. There are three significant differences: The Cisco NX-OS allows BGP to be enabled and disabled globally. It utilizes a hierarchical configuration that makes it easier to read. The Cisco NX-OS does not enable any address families by default. Each address-family needs to be explicitly enabled. The following examples demonstrate this using the IPv4 unicast address family.


Cisco IOS CLI Cisco NX-OS CLI
Enabling the BGP Feature
Cisco IOS Software does not have the functionality to enable or disable BGP. feature bgp
Configuring a BGP Instance and Router ID
router bgp 10

bgp router-id 192.168.1.1

router bgp 10

router-id 192.168.1.1

Configuring a BGP Neighbor (Internal)
router bgp 10

neighbor 192.168.2.1 remote-as 10

neighbor 192.168.2.1 update-source Loopback0

router bgp 10

neighbor 192.168.2.1 remote-as 10

update-source loopback0

address-family ipv4 unicast

Configuring a BGP Neighbor (External)
router bgp 10

neighbor 192.168.10.2 remote-as 11

router bgp 10

neighbor 192.168.10.2 remote-as 11

address-family ipv4 unicast

Advertising a Network in an Address Family (IPv4)
router bgp 10

network 159.142.1.0 mask 255.255.255.0

network 159.142.254.0 mask 255.255.255.0

neighbor 192.168.10.2 remote-as 11

router bgp 10

address-family ipv4 unicast

network 159.142.1.0/24

network 159.142.254.0/24

neighbor 192.168.10.2 remote-as 11

address-family ipv4 unicast

Configuring Neighbor Authentication (MD5)
router bgp 10

neighbor 192.168.10.2 remote-as 11

neighbor 192.168.10.2 password cisco123

router bgp 10

neighbor 192.168.10.2 remote-as 11

password 3 a667d47acc18ea6b

address-family ipv4 unicast

Configuring an Aggregate Address (Summary-Only)
router bgp 10

network 159.142.1.0 mask 255.255.255.0

network 159.142.254.0 mask 255.255.255.0

aggregate-address 159.142.0.0 255.255.0.0 summary-only

neighbor 192.168.10.2 remote-as 11

router bgp 10

address-family ipv4 unicast

network 159.142.1.0/24

network 159.142.254.0/24

aggregate-address 159.142.0.0/16 summary-only

neighbor 192.168.10.2 remote-as 11

address-family ipv4 unicast

Generating a Default Route for a Neighbor
router bgp 10

neighbor 192.168.10.2 remote-as 11

neighbor 192.168.10.2 default-originate

router bgp 10

neighbor 192.168.10.2 remote-as 11

address-family ipv4 unicast

default-originate



Verification Command Comparison

The following table compares some useful show commands for verifying and troubleshooting a BGP network configuration.


Cisco NX-OS BGP Cisco IOS Software BGP Command Description
show bgp convergence - Displays global convergence information
show bgp process - Displays global BGP process information
show bgp sessions - Displays information for all neighbors
show bgp statistics - Displays global BGP process statistics
- - -
show ip bgp <option> show ip bgp Displays BGP Process and BGP table entries
show ip bgp x.x.x.x show ip bgp x.x.x.x Displays a specific network in the BGP table
show ip bgp x.x.x.x vrf - Displays a network in a specified VRF BGP table
show ip bgp x.x.x.x/len show ip bgp x.x.x.x mask Displays a specific prefix in the BGP table
show ip bgp x.x.x.x/len longer-prefix show ip bgp x.x.x.x mask longer-prefix Displays a prefix in the table with longer prefixes
show ip bgp all show ip bgp all Displays the BGP table for all protocol families
show ip bgp community <word> show ip bgp community <#> Displays routes with a specific regular expression
show ip bgp community <aa:nn> - Displays routes with a specific community value
show ip bgp community internet - Displays BGP routes advertised to the Internet
show ip bgp community no-advertise show ip bgp community no-advertise Displays BGP routes not advertised to peers
show ip bgp community no-export show ip bgp community no-export Displays BGP routes not exported to next AS
show ip bgp community no-export-spoofed - Displays BGP routes not sent to outside local AS
show ip bgp community-list <name> show ip bgp community-list <name> Displays a specific BGP community list
show ip bgp dampening dampened-paths show ip bgp dampening dampened-paths Displays all Dampened paths
show ip bgp dampening flap-statistics show ip bgp dampening flap-statistics Displays flap statistics for BGP routes
show ip bgp dampening history-paths - Displays all history paths
show ip bgp dampening parameters show ip bgp dampening parameters Displays all of the Dampening parameters
show ip bgp extcommunity <word> - Displays routes with a specific regular expression for extended communities
show ip bgp extcommunity-list <name> - Displays a specific BGP extended community list
show ip bgp filter-list show ip bgp filter-list Displays all routes matching a specified filter list
show ip bgp flap-statistics - Displays all BGP route flap statistics
show ip bgp ipv4 multicast <option> show ip bgp ipv4 multicast <option> Displays BGP IPv4 multicast address families
show ip bgp ipv4 unicast <option> show ip bgp ipv4 unicast <option> Displays BGP IPv4 unicast address families
show ip bgp neighbors show ip bgp neighbors Displays detailed neighbor information
show ip bgp neighbors x.x.x.x show ip bgp neighbors x.x.x.x Displays detailed information for a neighbor
show ip bgp nexthop x.x.x.x - Displays all routes matching a specified next-hop
show ip bgp nexthop-database - Displays the next-hop database
show ip bgp paths show ip bgp paths Displays all BGP paths
show ip bgp peer-policy - Displays BGP peer policy by specified name
show ip bgp peer-session - Displays information about a peer session
show ip bgp peer-template show ip bgp unicast ipv4 template Displays information about a peer template
show ip bgp prefix-list show ip bgp prefix-list Displays routes matching a specified prefix-list
show ip bgp regexp show ip bgp regexp Displays routes matching a regular-expression
show ip bgp received-paths - Displays the paths stored for soft reconfiguration
show ip bgp route-map show ip bgp route-map Displays BGP routes matching a route-map
show ip bgp summary show ip bgp summary Displays a summary list of neighbors and statistics
show ip bgp vrf show ip bgp vpnv4 vrf Displays information for a specified BGP VRF

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