Term
| What does the greater-than sign (>) mean inthe output of the show ip bgp command? |
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Definition
| The greater-than sign indicates the best path for a route selected by BGP. This is the route that is offered to the IP routing table. |
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Term
| What command is used to display the BGP routes that were not installed in the RIB? |
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Definition
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Term
| What command displays the status of all BGP connections? |
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Definition
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Term
| What command is used to view BGP updates as they're being sent? |
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Definition
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Term
| What are the different neighbor states that a BGP neighbor can be in? |
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Definition
- Idle - The router is searching the routing table to see whether a route exists to reach the neighbor. - Connect - The router found a route to the neighbor and has completed the 3-way TCP handshake. - Open sent - An open message was sent, with the parameters for the BGP session. - Open confirm - The router received agreement on the parameters for establishing a session. - Active - The router goes into active state if it doesn't receive a response to an open message - Established - Peering is established and routing begins. |
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Term
| What command is used to display information about the BGP connections to neighbors? |
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Definition
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Term
| What command is used to change the default local preference for all BGP routes advertised by a router? |
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Definition
| bgp default local-preference value |
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Term
| What command can be used to change the default MED value on a BGP router? |
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Definition
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Term
| What command is used to assign a weight to updates from a neighbor connection? |
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Definition
| neighbor {ip-address | peer-group} weight value |
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Term
| Describe the 2 BGP attributes that are related to aggregate addressing. |
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Definition
- Atomic aggregate - A well-known disctretionary attribute that informs the neighbor AS that the originating router has aggregated the routes. - Aggregator - An optional transitive attribute that specifies the BGP router ID and AS number of the router that preformed the route aggregation. |
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Term
| How does BGP handle redistribution when summarization is enabled? |
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Definition
| When summarization is enabled (with auto-summary), all redistrbuted subnets are summarized to their classful boundaries in the BGP table. When summarization is disabled, all redistributed subnets are present in their original form in the BGP table. |
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Term
| What command is used to create an aggregate, or summary, entry in the BGP table? |
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Definition
| aggregate-address ip-address mask [summary-only] [as-set] |
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Term
| When summarizing routes in BGP, what is the difference between using the network command and using the aggregate-address command? |
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Definition
| The network command only advertises summaries that already exist in the IP routing table. With the aggregate-address command aggregates only networks that are already in the BGP table. |
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Term
| What command is used to create a prefix list? |
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Definition
| ip prefix-list {list-name | list-number} [seg value] {permit | deny} network/length [ge value] [le value] |
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Term
| What command is used to filter BGP neighbor information as specified in a prefix list? |
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Definition
| neighbor {ip-address | peer-group} prefix-list list-name {in | out} |
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Term
| What command is used to add a text description for a prefix list? |
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Definition
| ip prefix-list list-name description text |
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Term
| What command is used to display detailed information about all prefix-lists? |
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Definition
show ip prefix-list [detail | summary]
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Term
| What command is used to display detailed information about a specific prefix-list? |
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Definition
| show ip prefix-list [detail | summary] prefix-list-name |
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Term
| What are the different ways that a community number can be defined? |
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Definition
| The community value can be entered as one decimal number or in the format of AS:nn, where the AS is the autonomous system number, and nn is the lower 16-bit local number. |
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Term
| What command is used within a route map to set the BGP community attribute? |
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Definition
| set community {[community-number] [well-known-community] [additive]} | none |
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Term
| What command is used to specify that the BGP communities attribute should be sent to a BGP neighbor? |
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Definition
| neighbor {ip-address | peer-group} send-community |
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Term
| What is the default behavior for a router looking to send out a community attribute? |
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Definition
| By default, the communities attribute is not sent to any neighbors, since communities are stripped in outgoing BGP updates. |
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Term
| What command is used to create a community list for BGP and to control access to it? |
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Definition
| ip community-list list-number {permit | deny} community-number |
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Term
| Describe the basic use of route reflectors. |
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Definition
| A route reflector is a router that is configured to be the router allowed to advertise (reflect) routes it learned vian IBGP to other IBGP peers. |
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Term
| How does a route reflector handle updates that it receives? |
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Definition
| If the update if from a client peer, or from an EBGP peer, it sends the update to all nonclient and client peers (except the route's originator). But if the update is from a nonclient peer, it sends the update to all clients in the cluster. |
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Term
| What command allows you to configure a router as a BGP RR and to configure the specified neighbor as its client? |
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Definition
| neighbor ip-address route-reflector-client |
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Term
| What command is used to configure a cluster ID for a RR? |
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Definition
bgp cluster-id cluster-id |
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