The BGP Graceful Shutdown feature reduces or eliminates the loss of traffic along a link being shut down for maintenance. Routers always have a valid route available during the convergence process. Your software release may not support all the features documented in this module.
For the latest caveats and feature information, see Bug Search Tool and 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 table at the end of this module.
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There are times when planned maintenance operations cause routing changes in BGP. The goal of gracefully shutting down one or more BGP sessions is to minimize traffic loss during the planned shutdown and subsequent reestablishment of the sessions. The BGP Graceful Shutdown feature reduces or eliminates the loss of inbound or outbound traffic flows that were initially forwarded along the peering link that is being shut down for maintenance.
Lowering the local preference for paths received over the session being shutdown renders the affected paths less preferred by the BGP decision process, but still allows the paths to be used during the convergence while alternative paths are propagated to the affected devices. Therefore, devices always have a valid route available during the convergence process.
The feature also allows vendors to provide a graceful shutdown mechanism that does not require any router reconfiguration at maintenance time. The benefits of the BGP Graceful Shutdown feature are fewer lost packets and less time spent reconfiguring devices. The GSHUT community attribute is applied to a neighbor specified by the neighbor shutdown graceful command, thereby gracefully shutting down the link in an expected number of seconds.
The GSHUT community is specified in a community list, which is referenced by a route map and then used to make policy routing decisions.
To enable the BGP GSHUT enhancement feature on the device, you must configure either the community keyword or the local-preference keyword in the bgp graceful-shutdown all command. Use the activate keyword to activate graceful shutdown either across all neighbors or only across all VRF neighbors, across all BGP sessions. Configures the device to gracefully shut down the link to the specified peer in the specified number of seconds; advertises the route with the GSHUT Graceful Shutdown community; and advertises the route with another community or specifies a local preference value for the route, or both.
Make sure to specify an adequate amount of time for iBGP peers to converge and to choose an alternate path as the best path. If the graceful keyword is used in the neighbor shutdown command, at least one of the two attributes a community or local preference must be configured. You may configure both attributes.
If the graceful keyword is used in the neighbor shutdown command, the route is advertised with the GSHUT community by default. You may also set one other community for policy routing purposes. In this particular example, the route to the neighbor is configured to shut down in seconds, is advertised with the GSHUT community and communityand is configured with a local preference of The device receiving the advertisement looks at the community value s of the route and optionally uses the community value to apply routing policy.
Filtering routes based on a community is done with the ip community-list command and a route map.
OSPF Graceful Shutdown
During the graceful shutdown, the neighbor shutdown command is not nvgened. Configures a community list and permits or denies routes that have the GSHUT community to the community list. If you specify other communities in the same statement, there is a logical AND operation and all communities in the statement must match the communities for the route in order for the statement to be processed.
This example gracefully shuts down the link to the specified neighbor in seconds, adds the GSHUT community to the route, and sets a local preference of for the route.Save Digg Del. A router learns about unattached networks through static configuration or through dynamic routing protocols that distribute network topology information between routers. Routers try to select the best loop-free path in a network based on the destination network.
Link flaps, router crashes, and other unexpected events could impact the best path, so the routers must exchange information with each other so that the network topology updates during these types of events. Routing protocols are classified as either an Interior Gateway Protocol IGP or an Exterior Gateway Protocol EGPwhich indicates whether the protocol is designed for exchanging routes within an organization or between organizations.
In IGP protocols, all routers use a common logic within the routing domain to find the shortest path to reach a destination. EGP protocols may require a unique routing policy for every external organization that it exchanges routes.
When BGP was created, the primary design consideration was for IPv4 inter-organization connectivity on public networks, such as the Internet, or private dedicated networks. BGP is the only protocol used to exchange networks on the Internet, which has more thanIPv4 routes and continues to grow.
BGP prefers stability within the network, because a link flap could result in route computation for thousands of routes. Two blocks of private ASNs are available for any organization to use as long as they are never exchanged publicly on the Internet. In the event that an organization does not meet those guidelines, it should use the ASN provided by its service provider.
BGP attaches path attributes PA associated with each network path. Well-known mandatory attributes must be included with every prefix advertisement, whereas well-known discretionary attributes may or may not be included with the prefix advertisement.3 of 9 barcode font excel
Optional attributes do not have to be recognized by all BGP implementations. Optional attributes can be set so that they are transitive and stay with the route advertisement from AS to AS. BGP is a path vector routing protocol and does not contain a complete topology of the network-like link state routing protocols.
BGP behaves similar to distance vector protocols to ensure a path is loop free. An address-family correlates to a specific network protocol, such as IPv4, IPv6, and the like, and additional granularity through a subsequent address-family identifier SAFIsuch as unicast and multicast. These attributes are carried inside BGP update messages and are used to carry network reachability information for different address families.
Both terms are the same thing. Network engineers and vendors continue to add functionality and feature enhancements to BGP. This allows for a routing policy in one address-family to be different from a routing policy in a different address family even though the router uses the same BGP session to the other router.
BGP sessions are always point-to-point and are categorized into two types:. Administrative distance AD is a rating of the trustworthiness of a routing information source. If a router learns about a route to a destination from more than one routing protocol, and they all have the same prefix length, AD is compared.
The preference is given to the route with the lower AD.
All rights reserved. Join Sign In.Similar to using the shutdown command on an interface, there is also a shutdown command for OSPF. This allows you to gracefully stop the OSPF routing process without removing the configuration from your router. You can do this globally or on the interface level.
This will:. If you shut OSPF on the interface level with the ip ospf shutdown command, it will do this:. Hi Rene, In which situation we can use this command?? Actually I cant find out the importance of this command in my view. Could you please tell me the uses of this command?? All traffic that has another path through the network will be directed to that alternate path. A graceful shutdown of the OSPF protocol can be initiated using the shutdown command in router configuration mode.
Essentially, the advantage here is that the router that is being shutdown will send out messages to other OSPF routers informing them of the shut. Hi, Still bit confusion,Exactly, when we are going to use Graceful shutdown…?
Possiblity situations? Graceful shutdown for OSPF is useful when you want to remove or disable a router for maintenance purposes for example in the least disruptive manner.
What it does is it lets other routers know about its intentions and gives an opportunity to the other routers to find alternative routes to their destinations. This way, when the router is actually shut down, rerouting has already been established and end users should detect little or no change in the network performance.
Hi Laz- Brilliant explaination!!! Ask a question or join the discussion by visiting our Community Forum. Skip to content Search for: Search. This will trigger other OSPF routers to fall back to init state. If you shut OSPF on the interface level with the ip ospf shutdown command, it will do this: Drop all neighbor adjacencies on the interface you selected.
Flood updated LSAs where all information prefix, neighbors from the selected interface is removed.Ragnarok pixel bot
This will trigger other OSPF router to fall back to init state. Configurations Want to take a look for yourself? Here you will find the configuration of each device. Forum Replies Hi Rene, In which situation we can use this command?? Essentially, the advantage here is that the router that is being shutdown will send out messages to other OSPF routers informing them of the shut Continue reading in our forum.Funny game names generator
Address-family configuration mode is not a group change mode; running-config is changed immediately after commands are executed. The exit command does not affect the configuration.Basic BGP troubleshooting in MPLS VPN networks
Running-config displays address family commands in sub-blocks of the BGP configuration. The following commands are available in address family configuration mode:. The no address-family and default address-family commands delete the specified address-family from running-config by removing all commands previously configured in the corresponding address-family mode.
The exit command returns the switch to router-BGP configuration mode. Options include:. Aggregate routes combine the characteristics of multiple routes into a single route that the switch advertises. Aggregation can reduce the amount of information that a BGP speaker is required to store and transmit when advertising routes to other BGP speakers. Aggregate routes are advertised only after they are redistributed. The advertised address of the aggregate is entered as an IP subnet; any routes configured on the switch that lie within that subnet then become contributors to the aggregate.
Note that on Arista switches the BGP aggregate route will become active if there are any available contributor routes on the switch, regardless of the originating protocol. This includes routes configured statically. Aggregate routes are redistributed automatically, and their redistribution cannot be disabled.
Command options affect the attributes associated with the aggregated route, the advertisement of the contributor routes that comprise the aggregate, and which contributor routes are included. Command options affect the following aggregate routing attributes:. For example, for the aggregate 1. The no aggregate-address and default aggregate-address commands remove the corresponding aggregate-address command from running-config.
Deny clauses and match commands in permit clauses are ignored. This can contribute to dropped traffic. If a preferred route is available through another protocol like OSPFthe BGP route will become inactive and not be advertised; if the preferred route is lost, there is no available route to the affected peers.Frankenstein quotes
Advertising inactive BGP routes minimizes traffic loss by providing alternative routes. Inactive route advertisement is configured globally, but the global setting can be overridden on a per-VRF basis. The no bgp advertise-inactive and default bgp advertise-inactive commands restore the default BGP behavior advertising only active routes by removing the corresponding bgp advertise-inactive command from running-config.Command introduced before JunosE Release 7. Shuts down the specified neighbor or peer group without removing the neighbor or peer group configuration.
The no version reenables a neighbor or peer group that was previously shut down. The default version removes the explicit configuration from the peer or peer group and reestablishes inheritance of the feature configuration. All rights reserved. Help us improve your experience. Let us know what you think. Do you have time for a two-minute survey? Maybe Later. Navigation CLI Explorer. Table of Contents. Thank You! DynamicBook 0. Select All. Rate and give feedback:.
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Need product assistance? Contact Juniper Support. Description Shuts down the specified neighbor or peer group without removing the neighbor or peer group configuration.
If you specify a BGP peer group by using the peerGroupName argument, all the members of the peer group inherit the characteristic configured with this command, unless it is overridden for a specific peer. Previous Page Next Page.To match on paths that are marked tagged with a specific path-marking policy, use the match additional-paths advertise-set command in route-map configuration mode.
To remove the match additional-paths advertise-set command from the configuration file, use the no form of this command. Optional Matches on paths that are tagged with best number tag. The best number keyword and argument are mutually exclusive with the best-range range-start range-end keyword and arguments.
That is, the configuration of one disallows the configuration of the other. Optional Matches on paths that are tagged with best n this starting number or any number in the range specified. Optional Matches on paths that are tagged with best n this ending number or any number in the range specified. The range-end value can be 1, 2, or 3. If the range-start equals the range-endthen one specific path the n th best path of the network is matched.
Otherwise, the best paths in the range are matched. Optional Matches on paths that are tagged with the group-best tag. Optional Matches on paths that are tagged with the all tag. Use this command in a route map to filter the advertisement of additional paths.
Paths that have the same path marking tag as the marking that is configured in the match additional-paths advertise-set command match the route map entry and are permitted or denied. A tag is an advertise-set, as defined in the bgp additional-paths select command.
If match additional-paths advertise-set best number is configured, any path that has the tag best number or a lower number tag matches the route map entry. You can specify more than one selection policy in one match additional-paths advertise-set command; you must specify at least one selection policy if you use this command.Best map for logging fs19
For practical purposes, it is preferable to use best number rather than best-range range-start range-end. You can configure only one match additional-paths advertise-set command in the route map. If you configure more than one match additional-paths advertise-set command, the latest command overwrites the previous match additional-paths advertise-set command. You can optionally specify in the route map one or more set commands to set characteristics of a path.
Although you can specify a route map that matches on paths that have marking policies other than the paths you want to advertise, you will typically create a route map that matches on the paths that you want to advertise specified by the neighbor advertise additional-paths command.Provides for the shutdown of a peer or peer group while maintaining peer configuration. Specifies the peer group for this EBGP neighbor to shutdown.
Description: IPriori provides for the shutdown of a BGP peering session without removing the associated peer configuration. A neighbor shutdown terminates any active sessions and removes all associated routing information for the peer or peer group while maintaining all the configuration associated with the peer.
Use the neighbor shutdown command in router configuration mode specifying the peer or peer group for which sessions will be terminated and associated routing information removed. Use the no neighbor shutdown command in router configuration mode specifying the peer or peer group to reactivate sessions that have been shutdown. Command Mode: Router configuration.
Example 1: The following example enters AS and performs a shutdown on a peer and peer group:. Example 2: The following example enters AS and enables a peer and peer group that had been shutdown:.
Related Commands: show ip bgp show ip bgp summary.
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