- play_arrow Overview
- play_arrow Configuring BGP Session Attributes
- play_arrow Configuring BGP Session Policies
- play_arrow Enabling Load Balancing for BGP
- play_arrow Configuring Graceful Restart for BGP
- play_arrow Configuring Multiprotocol for a BGP Session
- play_arrow Configuring BGP CLNS
- play_arrow Using Route Reflectors and Confederations for BGP Networks
- play_arrow Configuring BGP Security
- play_arrow Configuring BGP Route Flap Damping and Error Handling
- play_arrow Configuring BGP-Based VPN
- play_arrow Monitoring and Troubleshooting
- play_arrow Configuration Statements and Operational Commands
BGP Route Prioritization
Understanding BGP Route Prioritization
While BGP is one of the most widely deployed routing protocols in use today, carrying not only network layer reachability information (NLRI) but also many types of VPN reachability information, it is notable that the protocol does not specify how the information is ordered in BGP update messages. This decision is left to the implementation.
In large-scale systems, BGP might take a significant amount of time to exchange its routing information between systems. This is especially true during BGP startup, route refresh operations, and when assisting with graceful restart. In order to handle the large amount of information that needs to be processed, BGP route processing is accomplished with the use of queues. Outbound routes are placed in output queues for processing. BGP route prioritization is introduced in Junos OS Release 16.1 as a means to allow the user to deterministically prioritize BGP update messages. BGP route prioritization is a process that operates strictly on the output queues., helping to order the information that is being sent to BGP peer routers.
In the default configuration, that is, when no output-queue-priority configuration or policy that overrides priority exists, the routing
protocol process (rpd) enqueues BGP routes into the output queue per
routing information base (RIB).
A RIB, which is also known as a routing table, corresponds to both
a specific address family, such as inet.0, and to routing instance
tables such as vrf.inet.0. While processing output queues, the BGP
update code flushes the output queue for the current RIB before moving
on to the next RIB that has a non-empty output queue.
There is no attempt to automatically prioritize routes even if there is a theoretical possibility of doing so. Prioritizing individual routes is, therefore, left completely to the user.
If BGP route priorities are changed for a peer group, the BGP peer sessions get reset.
- Use Cases for BGP Route Prioritization
- Properties of BGP Route Prioritization
- Understanding Queue Priority and Fairness
- Queue Servicing Procedure
Use Cases for BGP Route Prioritization
Table 1 shows the types of routes that would benefit from route prioritization and some notes about why they would benefit from it. Examples of those types of routes are also included. Prioritizing these routes within a given large-scale environment can help routers to react more quickly to important route changes.
Route or Update Type | Notes | Example |
|---|---|---|
Prefixes used for resolving BGP next hops to an immediate forwarding next hop | Changes to these prefixes should be made as soon as possible. |
|
Routes used for tunnel endpoints | Tunnel endpoints such as GRE or MPLS are often used as BGP next hops. | BGP labeled unicast routes |
Route types that are critical for the operation of a protocol feature | For some VPN protocols, certain route types are used to trigger time sensitive changes within the protocol. Changes to these routes must be made as soon as possible. |
|
Service provider infrastructure routes | These routes are critical to a service provider’s ability to conduct business. Without accurate and up-to-date routes, the service provider might not be able to provide some of its service offerings. |
|
Network topology changes | These should be prioritized ahead of simple route refreshes. |
|
Properties of BGP Route Prioritization
BGP route prioritization in Junos OS is implemented using a set of 17 prioritized (numbered) output queues that are serviced by a user-configurable token mechanism. This section describes the prioritized output queues, the operation of the token system, and assignment of routes to queues.
- Prioritized Output Queues
- Assignment of Routes to Queues
- When Routes are Assigned to Queues
- Work Token Mechanism
Prioritized Output Queues
Table 2 shows the available output queues and their function within the prioritization system. The prioritization system functions on a traditional low, medium, and high priority scale with 1 being the lowest priority and 16 being the highest priority.
Queue | Function |
|---|---|
expedited | This is the highest priority output queue. Routes in this class are guaranteed some portion of the output queue processing while flushing the output queue. This queue has no number and is referred to in the configuration by its name. |
1 (lowest priority) | This is the lowest priority output queue. This is the default priority queue, meaning that routes with no explicit queue assignment from either automatic protocol determination or user policy are placed in this queue by default. Route refresh messages are placed in this queue by default. |
2 - 16 (low - high priority) | These output queues range in priority from lowest priority (2) to highest priority (16). They are assigned routes based on user policy or BGP peer configuration. Routes in a higher priority output queue can preempt the routes in lower priority queues. |
Assignment of Routes to Queues
Assigning routes to the various queues can be accomplished by setting and assigning BGP export policies. This means that route priority can vary in each BGP peer group as well as in specific neighbor configurations within the BGP peer groups. You can also assign routes to queues using the action portion of a policy statement. Assignment of routes to queues by the action of a policy statement will override assignments made by BGP configuration.
When Routes are Assigned to Queues
Prioritized routes are added to their respective queues only during route processing. This generally occurs under the following conditions:
When routes are received from established BGP neighbors.
During a routing table walk, such as during reconfiguration or the initial establishment of a peer.
Routing table walks process routes sequentially in a table, based on the system’s
internal routing table order. For example, inet.0,
inet6.0, and so on. This internal order is predetermined
and cannot be modified by the operator.
If higher-priority routes reside in routing tables processed later in the order, these routes may be added to the queues after lower-priority routes encountered earlier in the process.
Work Token Mechanism
Tokens correspond to the work to create a BGP update message.
All the queues are assigned tokens that are stored in buckets. The
number of tokens in a given bucket is user-configurable. In this way,
users can craft policies that permit their routes to be served in
the proportions they prefer. The configuration of the priority scheduler
is accomplished globally within BGP at the [edit protocols bgp] hierarchy level. By default, all priority queues have at least 1
token in their bucket to ensure that misconfigured priorities do not
starve.
Understanding Queue Priority and Fairness
The scheme used by BGP route prioritization focuses on two elements: fairness and priority:
Fairness means that when there is work to do in any given queue, other queues are guaranteed to get some work done at some point. How much work each queue is permitted to get done is determined by the number of tokens assigned to each priority.
Priority means that when there is competing work and fairness has been ensured, to always choose the more important work.
For example, presume three classes of priority: low, medium, and high. These could be assigned to queues 1, 2, and 3, respectively. Alternatively, they could be assigned to queues 3, 6, and 9. For fairness, if the decision is that high priority gets 50% of the available work, medium gets 35%, and low gets the remaining 15%, tokens can be assigned as 50 to high, 35 to medium, and 15 to low. Alternatively, tokens can be assigned as 5 to high, 4 to medium, and 2 to low. You can assign any of the 17 queues any value between 1 and 100. The ratio of the number of tokens in a single queue to the total number of tokens in all queues gives the percentage of work that will be done in each queue.
Priority is most important when work appears in a queue while tokens are in the process of being spent in another queue by the work scheduler. Table 3 shows the starting point for an example of this.
Priority Queue (Queue Number) | Number of Tokens Assigned to Queue | Number of Tokens Left in Queue | Number of Entries in Queue |
|---|---|---|---|
High (9) | 50 | 50 | 0 |
Medium (6) | 35 | 15 | 5000 |
Low (3) | 15 | 15 | 10000 |
If we assume that the work scheduler is processing the medium queue (queue number 6) and has spent 20 tokens, then there are 15 tokens left to be spent on the remaining entries in the medium queue and 15 tokens left to be spent in the low priority queue. If 5 entries arrive in the expedited queue prior to the next run of the work scheduler, those 5 entries will be sent first because there are still 50 tokens left in the expedited queue.
Queue Servicing Procedure
The queue servicing procedure operates per-BGP peer group with each group maintaining its own token buckets.
Token buckets for each priority start full either at the configured number of tokens or at the default of 1.
Each time a route entry is pulled from a queue to start a BGP update, a token is subtracted from that queue.
While the expedited queue has tokens, every other queue entry is drawn from the expedited queue, subject to the route packing rules.
Entries are taken from the queue that has the highest priority. This means that if entries are added to a higher priority queue between runs of the queue servicing mechanism, and there are tokens available in that higher priority queue, the new entries in the higher priority queue are sent first, thus preempting entries in lower priority queues. If the higher priority queue has no work tokens available when the new entries arrive, the new entries are not sent until after the next token refresh.
Tokens are refreshed after all priority queues have been serviced (there are no entries remaining in any queue) or when all tokens are exhausted.
See Also
Example: Configuring the BGP Output Priority Scheduler and Global Address Family Priority
This example shows how to configure and test the system-wide BGP route priority scheduler.
- Requirements
- Overview
- Configuration
- Configure Global Output Priorities for a Route Family
- Configure a BGP Group Named test1
- Verification
Requirements
This example uses the following hardware and software components:
An MX Series router (R1) running Junos OS Release 16.1 or later
Before you configure the BGP route prioritization scheduler, be sure that the BGP protocol is running on the router.
Overview
The BGP route priority scheduler is used to control the amount of work done within the 17 output queues of the route prioritization system. The system uses a set of 17 prioritized output queues, per routing instance to which work tokens are assigned. All 17 prioritized output queues (1-16 and expedited) have 1 token assigned by default. Any number of tokens between 1 and 100 can be assigned to each of the 17 queues. Assigning tokens to the queues allows you to balance the amount of work performed on the routes within the queues. In addition, default settings for high, medium, and low priority queuing can be configured by assigning each keyword to a specific numbered output queue. In this example, we will configure each of the 17 priority queues with distinct numbers of work tokens and we also configure global output priorities for inet unicast routes and demonstrate inheritance by setting up some BGP groups to override global priority settings.
Configuration
Assign
update-tokensto each of the 17 output queues.Specify which numbered queues will be used as the default
high,medium, andlowpriority queues.Configure global output priorities for
inet unicastroutes.Configure a BGP group named test1 that will show group override capabilities.
Configure a BGP group named test2 that will show global inheritance.
- CLI Quick Configuration
- Configuring the Individual Output Priority Queues
- Configure Default Queues to Use for High, Medium, and Low Priority Route Updates
- Results
CLI Quick Configuration
To quickly configure this example, copy the
following commands, paste them into a text file, remove any line breaks,
change any details necessary to match your network configuration,
and then copy and paste the commands into the CLI at the [edit] hierarchy level.
set protocols bgp output-queue-priority expedited update-tokens 100 set protocols bgp output-queue-priority priority 1 update-tokens 1 set protocols bgp output-queue-priority priority 2 update-tokens 10 set protocols bgp output-queue-priority priority 3 update-tokens 15 set protocols bgp output-queue-priority priority 4 update-tokens 20 set protocols bgp output-queue-priority priority 5 update-tokens 25 set protocols bgp output-queue-priority priority 6 update-tokens 30 set protocols bgp output-queue-priority priority 7 update-tokens 35 set protocols bgp output-queue-priority priority 8 update-tokens 40 set protocols bgp output-queue-priority priority 9 update-tokens 45 set protocols bgp output-queue-priority priority 10 update-tokens 50 set protocols bgp output-queue-priority priority 11 update-tokens 55 set protocols bgp output-queue-priority priority 12 update-tokens 60 set protocols bgp output-queue-priority priority 13 update-tokens 65 set protocols bgp output-queue-priority priority 14 update-tokens 70 set protocols bgp output-queue-priority priority 15 update-tokens 75 set protocols bgp output-queue-priority priority 16 update-tokens 80 set protocols bgp output-queue-priority defaults low priority 1 set protocols bgp output-queue-priority defaults medium priority 10 set protocols bgp output-queue-priority defaults high expedited set protocols bgp group reflector local-address 198.51.100.140 set protocols bgp family inet unicast output-queue-priority priority 1 set protocols bgp family inet unicast route-refresh-priority priority 2 set protocols bgp family inet unicast withdraw-priority priority 3 set protocols bgp group test1 family inet unicast output-queue-priority priority 4 set protocols bgp group test1 family inet unicast route-refresh-priority priority 6 set protocols bgp group test1 peer-as 64511 set protocols bgp group test1 local-as 64511 set protocols bgp group test1 neighbor 224.223.1.1 set protocols bgp group test1 neighbor 224.223.2.2 family inet unicast output-queue-priority priority 7 set protocols bgp group test1 neighbor 224.223.2.2 family inet unicast route-refresh-priority priority 8 set protocols bgp group test1 neighbor 224.223.2.2 family inet unicast withdraw-priority expedited set protocols bgp group test2 peer-as 64513 set protocols bgp group test2 local-as 64511 set protocols bgp group test2 neighbor 224.223.3.3
Configuring the Individual Output Priority Queues
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the Junos OS CLI User Guide.
Assign update tokens to each of the 17 prioritized output queues
content_copy zoom_out_map[edit protocols bgp output-queue-priority] user@R1# set expedited update-tokens 100 user@R1# set priority 1 update-tokens 1 user@R1# set priority 2 update-tokens 10 user@R1# set priority 3 update-tokens 15 user@R1# set priority 4 update-tokens 20 user@R1# set priority 5 update-tokens 25 user@R1# set priority 6 update-tokens 30 user@R1# set priority 7 update-tokens 35 user@R1# set priority 8 update-tokens 40 user@R1# set priority 9 update-tokens 45 user@R1# set priority 10 update-tokens 50 user@R1# set priority 11 update-tokens 55 user@R1# set priority 12 update-tokens 60 user@R1# set priority 13 update-tokens 65 user@R1# set priority 14 update-tokens 70 user@R1# set priority 15 update-tokens 75 user@R1# set priority 16 update-tokens 80
Configure Default Queues to Use for High, Medium, and Low Priority Route Updates
Step-by-Step Procedure
- content_copy zoom_out_map
[edit protocols bgp output-queue-priority] user@R1# set defaults low priority 1 user@R1# set defaults medium priority 10 user@R1# set defaults high expedited
Results
To confirm the configuration, issue the show bgp
output-scheduler command from operational mode:
Configure Global Output Priorities for a Route Family
Procedure
Step-by-Step Procedure
Configure the global
output-queue-priorityforinet unicastroutes:content_copy zoom_out_map[edit bgp family inet unicast] user@R1# set output-queue-priority priority 1 user@R1# set route-refresh-priority priority 2 user@R1# set withdraw-priority priority 3
Configure a BGP Group Named test1
Procedure
Step-by-Step Procedure
Configure the group
test1to override global output priorities and include one neighbor that overrides the group and one neighbor that does not.content_copy zoom_out_map[edit protocols bgp group test1] user@R1# set family inet unicast output-queue-priority priority 4 user@R1# set family inet unicast route-refresh-priority priority 6 user@R1# set peer-as 64511 user@R1# set local-as 64511 user@R1# set neighbor 224.223.1.1 user@R1# set neighbor 224.223.2.2 family inet unicast output-queue-priority priority 7 user@R1# set neighbor 224.223.2.2 family inet unicast route-refresh-priority priority 8 user@R1# set neighbor 224.223.2.2 family inet unicast withdraw-priority expedited
Configure a BGP Group Named test2
Step-by-Step Procedure
Configure the BGP group
test2to accept global defaults.content_copy zoom_out_map[edit protocols bgp group test2] user@R1# set peer-as 64513 user@R1# set local-as 64511 user@R1# set neighbor 224.223.3.3
Verification
- Verifying the BGP Output Scheduler Configuration
- Verify Group Configuration, Group Override, and Neighbor Override
- Verify Inheritance from Global Priority Settings
Verifying the BGP Output Scheduler Configuration
Purpose
To verify the configuration of the BGP output scheduler,
issue the show bgp output-scheduler command from operational
mode.
Action
user@R1> show bgp output-scheduler user@R1> show bgp output-scheduler Instance: master Class Tokens ------------ ------ Priority 1 1 Priority 2 10 Priority 3 15 Priority 4 20 Priority 5 25 Priority 6 30 Priority 7 35 Priority 8 40 Priority 9 45 Priority 10 50 Priority 11 55 Priority 12 60 Priority 13 65 Priority 14 70 Priority 15 75 Priority 16 80 Expedited 100 Priority Class -------- ------------ low Priority 1 medium Priority 10 high Expedited
Meaning
The output shows that the output scheduler configuration was successful in applying the proper number of tokens to each output queue and that the high, medium, and low priority keywords were assigned to the proper output queues.
Verify Group Configuration, Group Override, and Neighbor Override
Purpose
To verify that the configured groups demonstrate group
override, neighbor override and inheritance, issue the show bgp
group group-name command from operational
mode.
Action
user@R1> show bgp group test1
Group Type: Internal AS: 64511 Local AS: 64511
Name: test1 Index: 2 Flags: <>
Options: <LocalAS>
Holdtime: 0
NLRI inet-unicast:
OutQ: priority 7 RRQ: priority 8 WDQ: expedited
Local AS: 64511 Local System AS: 64511
Total peers: 1 Established: 0
224.223.2.2
Group Type: Internal AS: 64511 Local AS: 64511
Name: test1 Index: 1 Flags: <Export Eval>
Options: <LocalAS>
Holdtime: 0
NLRI inet-unicast:
OutQ: priority 4 RRQ: priority 6 WDQ: priority 3
Local AS: 64511 Local System AS: 64511
Total peers: 1 Established: 0
224.223.1.1
Meaning
The output shows that the output queue priority for
peer 224.223.2.2 is 7, the route refresh priority is 8, and the withdraw
priority is expedited. While the output queue priority for neighbor
224.223.1.1 is 4, the route refresh priority is 6, and the withdraw
priority is the default setting for the family inet unicast, or 3.
Verify Inheritance from Global Priority Settings
Purpose
To verify that groups that are not configured to override
the global BGP route prioritization settings, issue the show
bgp group group-name command at the operational
level.
Action
user@R1> show bgp group test2
Group Type: External Local AS: 64511
Name: test2 Index: 3 Flags: <Export Eval>
Options: <LocalAS>
Holdtime: 0
NLRI inet-unicast:
OutQ: priority 1 RRQ: priority 2 WDQ: priority 3
Local AS: 64511 Local System AS: 64511
Total peers: 1 Established: 0
224.223.3.3
Meaning
The output shows that the default route priorities
for inet unicast routes in the test2 group match
the global configuration.
Example: Controlling Routing Table Convergence Using BGP Route Prioritization
The following example configures BGP route prioritization
in order to allow inet labeled-unicast routes to converge
before inet unicast routes.
Requirements
This example uses the following hardware and software components:
An MX-Series router (R1) running Junos OS Release 16.1 or later that will be the focus of the example.
A second router (R2) configured as an internal BGP peer with R1.
A BGP route reflector (RR) that will be used to populate the routing tables of R1. In this example, we will not configure the route reflector.
Overview
The BGP route prioritization feature is designed to allow the prioritization of outbound BGP update messages in a router. Using BGP route prioritization enables the user to ensure that more important BGP route updates, such as GRE or MPLS tunnel endpoint changes, are sent out before less important BGP route updates, such as route refresh updates.
In this example, we will configure R1 to treat inet labeled-unicast route updates to R2 as higher priority than inet unicast route updates. To do this, we will configure the R2 router to accept
both inet unicast and inet labeled-unicast routes
from its peer router, R1. Then we will populate the inet.0 routing table on R1 from a route reflector and import a portion
of that table into the labeled-unicast table, inet.3 using rib-group import. As the routes are queued on R1,
we can validate the operation by observing whether the routes in the inet.3 RIB are flushed before the remainder of the routes in
the inet.0 RIB.
Configure BGP Route Prioritization
Configure R2 as a BGP peer of R1.
On R1:
Configure the router R2 as a peer of router R1.
Create a BGP group named reflector that will be used to obtain Internet routes from a route reflector.
Create a BGP group named internal that will be used for assigning the labeled-unicast traffic to a higher priority output-queue.
Create a RIB group into which the routes received from the reflector are imported.
Create the policy that determines what portion of the
inet.0RIB is imported into the RIB group.
CLI Quick Configuration
To quickly configure this example, copy the
following commands, paste them into a text file, remove any line breaks,
change any details necessary to match your network configuration,
and then copy and paste the commands into the CLI at the [edit] hierarchy level.
Router R2
set protocols bgp group internal type internal set protocols bgp group internal family inet unicast set protocols bgp group internal family inet labeled-unicast rib inet.3 set protocols bgp group internal peer-as 64511 set protocols bgp group internal local-as 64511 set protocols bgp group internal neighbor 192.0.2.1
Router R1
set protocols bgp group internal type internal set protocols bgp group internal hold-time 900 set protocols bgp group internal family inet unicast withdraw-priority expedited set protocols bgp group internal family inet labeled-unicast output-queue-priority priority 2 set protocols bgp group internal family inet labeled-unicast rib inet.3 set protocols bgp group internal family inet-vpn unicast set protocols bgp group internal local-as 64511 set protocols bgp group internal neighbor 192.0.2.2 local-address 192.0.2.1 set protocols bgp group reflector local-address 203.0.113.225 set protocols bgp group reflector family inet unicast rib-group into3 set protocols bgp group reflector peer-as 64500 set protocols bgp group reflector local-as 64496 set protocols bgp group reflector neighbor 192.51.100.71 multihop set policy-options policy-statement match-all then accept set routing-options rib-groups into3 import-rib inet.0 set routing-options rib-groups into3 import-rib inet.3 set routing-options rib-groups into3 import-policy match-long set policy-options policy-statement match-long term a from route-filter 192.0.0.0/8 prefix-length-range /20-/24 set policy-options policy-statement match-long term a then accept set policy-options policy-statement match-long then reject set policy-options policy-statement match-all then accept
Procedure
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the Junos OS CLI User Guide.
To configure R2:
Configure a BGP group named internal.
content_copy zoom_out_map[edit protocols bgp group internal] user@R2# set type internal user@R2# set family inet unicast user@R2# set family inet labeled-unicast rib inet.3 user@R2# set peer-as 64511 user@R2# set local-as 64511 user@R2# set neighbor 192.0.2.1
Step-by-Step Procedure
To configure R1:
Configure a BGP group named reflector that receives routes from the RR.
content_copy zoom_out_map[edit protocols bgp group reflector] user@R1# set local-address 203.0.113.225 user@R1# set family inet unicast rib-group into3 user@R1# set peer-as 64500 user@R1# set local-as 64496 user@R1# set neighbor 192.51.100.71 multihop
Configure a BGP group named internal
content_copy zoom_out_map[edit protocols bgp group internal] user@R1# set type internal user@R1# set hold-time 900 user@R1# set family inet unicast withdraw-priority expedited user@R1# set family inet labeled-unicast output-queue-priority priority 2 user@R1# set family inet labeled-unicast rib inet.3 user@R1# set family inet-vpn unicast user@R1# set local-as 64511 user@R1# set neighbor 192.0.2.2 local-address 192.0.2.1
Configure a RIB group named into3
content_copy zoom_out_map[edit routing-options rib-groups into3] user@R1# set import-rib inet.0 user@R1# set import-rib inet.3 user@R1# set import-policy match-long
Configure a routing policy named match-long
content_copy zoom_out_map[edit policy-options policy-statement match-long] user@R1# set term a from route-filter 192.0.0.0/8 prefix-length-range /20-/24 user@R1# set term a then accept user@R1# set then reject
Configure a routing policy named match-all
content_copy zoom_out_map[edit policy-options policy-statement match-all] user@R1# set then accept
Verification
Verifying that Neighbor Updates are Properly Prioritized
Purpose
To confirm that route updates are being placed in the proper queues and that the queues are updating.
Action
To see the route updates that are queued for the BGP neighbor 192.0.2.2, issue the show
bgp neighbor output-queue 192.0.2.2 command from operational
mode.
The
outputs show that inet-unicast routes are advertised before
inet-labeled-unicast routes.
user@R1> show bgp neighbor output-queue 192.0.2.2 Peer: 192.0.2.2+179 AS 64511 Local: 192.0.2.1+63704 AS 64511 Output Queue[0]: 502701 (inet.0, inet-unicast) Priority 1 : 502701 Priority 2 : 0 Priority 3 : 0 Priority 4 : 0 Priority 5 : 0 Priority 6 : 0 Priority 7 : 0 Priority 8 : 0 Priority 9 : 0 Priority 10: 0 Priority 11: 0 Priority 12: 0 Priority 13: 0 Priority 14: 0 Priority 15: 0 Priority 16: 0 Expedited : 0
user@R1> show bgp neighbor output-queue 192.0.2.2 Peer: 192.0.2.2+179 AS 64511 Local: 192.0.2.1+63704 AS 64511 Output Queue[1]: 6687 (inet.3, inet-labeled-unicast) Priority 1 : 0 Priority 2 : 6687 Priority 3 : 0 Priority 4 : 0 Priority 5 : 0 Priority 6 : 0 Priority 7 : 0 Priority 8 : 0 Priority 9 : 0 Priority 10: 0 Priority 11: 0 Priority 12: 0 Priority 13: 0 Priority 14: 0 Priority 15: 0 Priority 16: 0 Expedited : 0 user@R1> show bgp neighbor output-queue 192.0.2.2 Peer: 192.0.2.2+179 AS 64511 Local: 192.0.2.1+63704 AS 64511 Output Queue[0]: 491187 (inet.0, inet-unicast) Priority 1 : 491187 Priority 2 : 0 Priority 3 : 0 Priority 4 : 0 Priority 5 : 0 Priority 6 : 0 Priority 7 : 0 Priority 8 : 0 Priority 9 : 0 Priority 10: 0 Priority 11: 0 Priority 12: 0 Priority 13: 0 Priority 14: 0 Priority 15: 0 Priority 16: 0 Expedited : 0 user@R1> show bgp neighbor output-queue 192.0.2.2 Peer: 192.0.2.2+179 AS 64511 Local: 192.0.2.1+63704 AS 64511 Output Queue[1]: 0 (inet.3, inet-labeled-unicast) Priority 1 : 0 Priority 2 : 0 Priority 3 : 0 Priority 4 : 0 Priority 5 : 0 Priority 6 : 0 Priority 7 : 0 Priority 8 : 0 Priority 9 : 0 Priority 10: 0 Priority 11: 0 Priority 12: 0 Priority 13: 0 Priority 14: 0 Priority 15: 0 Priority 16: 0 Expedited : 0
Meaning
The output from show bgp neighbor output-queue
192.0.2.2 shows that the labeled unicast route updates are placed
in the priority 2 output queue and that the priority 2 output queue
is emptied before the unicast route updates that are in the priority
1 output queue.
