HP 5500 Ei 5500 Si Switch Series Configuration Guide
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205
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Inject a network to the BGP
routing table. network
ip-address [ mask |
mask-length ] route-policy
route-policy-name Optional.
Not injected by default.
Configuring BGP route redistribution
BGP does not find routes by itself. Rather, it redistributes routing information in the local AS from other
routing protocols. During route redistribution, you can configure BGP to filter...](http://img.usermanuals.tech/thumb/36/58909/w64_hp-5500-ei-5500-si-switch-series-configuration-guide-893.png "Page 894
205
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Inject a network to the BGP
routing table. network
ip-address [ mask |
mask-length ] route-policy
route-policy-name Optional.
Not injected by default.
Configuring BGP route redistribution
BGP does not find routes by itself. Rather, it redistributes routing information in the local AS from other
routing protocols. During route redistribution, you can configure BGP to filter...")
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207
To advertise a default route to a peer or peer group:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Advertise a default route to a
peer or peer group. peer { group-name |
ip-address }
default-route-advertise [ route-policy
route-policy-name ] Not advertised by
default.
Configuring BGP route distribution/reception filtering policies
Configuration prerequisites
Configure following filters as needed:
•
ACL
• IP...](http://img.usermanuals.tech/thumb/36/58909/w64_hp-5500-ei-5500-si-switch-series-configuration-guide-895.png "Page 896
207
To advertise a default route to a peer or peer group:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Advertise a default route to a
peer or peer group. peer { group-name |
ip-address }
default-route-advertise [ route-policy
route-policy-name ] Not advertised by
default.
Configuring BGP route distribution/reception filtering policies
Configuration prerequisites
Configure following filters as needed:
•
ACL
• IP...")
202 Task Remarks Configuring the interval for sending the same update Optional. Configuring BGP soft-reset Optional. Enabling the BGP ORF capability Optional. Enabling 4-byte AS number suppression Optional. Setting the DSCP value for BGP packets Optional. Enabling quick EBGP session reestablishment Optional. Enabling MD5 authentication for TCP connections Optional. Configuring BGP load balancing Optional. Forbiding session establishment with a peer or peer group Optional. Configuring a large scale BGP network Configuring BGP peer groups Optional. Configuring BGP community Optional. Configuring a BGP route reflector Optional. Configuring a BGP confederation Optional. Configuring BGP GR Optional. Enabling trap Optional. Enabling logging of peer state changes Optional. Configuring BFD for BGP Optional. Configuring BGP basic functions This section does not differentiate between BGP and MP-BGP. Configuration prerequisites The neighboring nodes are accessible to each other at the network layer. Creating a BGP connection A router ID is the unique identifier of a BGP router in an AS. • To ensure the uniqueness of a router ID and enhance network reliability, you can specify in BGP view the IP address of a local loopback interface as the router ID. • If no router ID is specified in BGP view, the global router ID is used. • If the global router ID is used and then it is removed, the system will select a new router ID. • If the router ID is specified in BGP view, using the undo router-id command can make the system select a new router ID. To create a BGP connection:
203
Step Command Remarks
1. Enter system view.
system-view N/A
2. Configure a global router ID.
router id router-id Optional.
Not configured by default.
If no global router ID is configured,
the highest loopback interface IP
address—if any—is used as the
router ID. If no loopback interface IP
address is available, the highest
physical interface IP address is used,
regardless of the interface status.
3.
Enable BGP and enter BGP
view. bgp
as-number Not enabled by default.
4. Specify a router ID.
router-id router-id Optional.
By default, the global router ID is
used.
5.
Specify a peer or a peer
group and its AS number. peer
{ group-name | ip-address }
as-number as-number Not specified by default.
6.
Enable the default use of IPv4
unicast address family for the
peers that are established
using the peer as-number
command. default ipv4-unicast
Optional.
Enabled by default.
7.
Enable a peer.
peer ip-address enable Optional.
Enabled by default.
A router can reside in only one AS,
so the router can run only one BGP
process.
8.
Configure a description for a
peer/peer group. peer {
group-name | ip-address }
description description-text Not configured by default.
You must create a peer group before
configuring it.
Specifying the source interface for TCP connections
BGP uses TCP as the transport layer protocol. By default, BGP uses the output interface of the optimal
route to a peer/peer group as the source interface fo
r establishing TCP connections to the peer or peer
group.
If a BGP router has multiple links to a peer, and th e source interface fails, BGP must reestablish TCP
connections, causing network oscillation. To enha nce stability of BGP connections, HP recommends
using a loopback interface as the source interface.
To establish multiple BGP connections between two routers, you must specify the source interface for
establishing TCP connections to each peer on the local router; otherwise, the local BGP router may fail
to establish TCP connections to a peer when using the outbound interface of the best route to the peer as
the source interface.
To specify the source interface for TCP connections:
204
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Specify the source interface
for establishing TCP
connections to a peer or peer
group. peer {
group-name | ip-address }
connect-interface interface-type
interface-number By default, BGP uses the outbound
interface of the best route to the BGP
peer or peer group as the source
interface for establishing a TCP
connection to the peer or peer
group.
Allowing establishment of EBGP connection to an indirectly
connected peer or peer group
Direct physical links must be available between EBGP peers. If they are not, use the
peer ebgp-max-hop
command to establish a TCP connection over multiple hops between two peers.
Do not configure the peer ebgp-max-hop command if the two EBGP peers are directly connected.
To allow establishment of EBGP connection to an indirectly connected peer or peer group:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Allow the establishment of
EBGP connection to an
indirectly connected peer or
peer group. peer { group-name
| ip-address }
ebgp-max-hop [ hop-count ] Optional.
Not allowed by default.
Controlling route generation
Different from IGP, BGP focuses on route genera
tion and advertisement control and optimal route
selection.
Generating BGP routes can be done in the following ways:
• Configure BGP to advertise local networks.
• Configure BGP to redistribute routes from other routing protocols, including the default route.
Configuration prerequisites
BGP connections must be created.
Injecting a local network
In BGP view, you can inject a local network to allow BGP to advertise to BGP peers. The origin attribute
of routes advertised in this way is IGP. You can also reference a routing policy to flexibly control route
advertisement. The network to be injected must be available in the local IP routing table.
To inject a local network:
205
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Inject a network to the BGP
routing table. network
ip-address [ mask |
mask-length ] route-policy
route-policy-name Optional.
Not injected by default.
Configuring BGP route redistribution
BGP does not find routes by itself. Rather, it redistributes routing information in the local AS from other
routing protocols. During route redistribution, you can configure BGP to filter routing information from
specific routing protocols.
The origin attribute of routes redistributed using the
import-route command is INCOMPLETE.
Only active routes can be redistributed. You can use the display ip routing-table protocol command to
display route stat e information.
To configure BGP route redistribution:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Enable route redistribution
from a routing protocol into
BGP. import-route
protocol [ { process-id
| all-processes } [ allow-direct |
med med-value | route-policy
route-policy-name ] * ] Not enabled by default.
The
allow-direct keyword is
available only when the specified
routing protocol is OSPF.
Enabling default route redistribution into BGP
Using the import-route command cannot redistribute a default route.
To enable default route redistribution into BGP:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Enable route redistribution
from a routing protocol into
BGP. import-route
protocol [ { process-id
| all-processes } [ allow-direct |
med med-value | route-policy
route-policy-name ] * ] Not redistributed by default.
The
allow-direct keyword is
available only when the specified
routing protocol is OSPF.
4. Enable default route
redistribution into BGP. default-route imported Optional.
Not enabled by default.
206
Controlling route distribution and reception
Configuration prerequisites
BGP connections must be created.
Configuring BGP route summarization
To reduce the routing table size on medium and large BGP networks, you need to configure route
summarization on BGP routers. BGP supports automatic and manual summarization modes. Manual
summary routes have a higher priority than automatic ones.
Configuring automatic route summarization
After automatic route summarization is configured, BGP summarizes redistributed IGP subnets to
advertise only natural networks. Routes injected with the network command cannot be summarized.
To configure automatic route summarization:
Step Command Remarks
1. Enter system view.
system-view N/A
2.
Enter BGP view.
bgp as-number N/A
3. Configure automatic route
summarization. summary automatic Not configured by
default.
Configuring manual route summarization
By configuring manual route summarization, you can
summarize both redistributed routes and routes
injected using the network command and determine the mask length for a summary route as needed.
To configure BGP manual route summarization:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Configure manual route
summarization. aggregate
ip-address { mask | mask-length }
[ as-set | attribute-policy route-policy-name |
detail-suppressed | origin-policy
route-policy-name | suppress-policy
route-policy-name ]* Not configured by
default.
Advertising a default route to a peer or peer group
After this task is configured, the BGP router sends a default route with the next hop being itself to the
specified peer or peer group. This action is taken regardless of whether the default route is available in
the routing table.
207
To advertise a default route to a peer or peer group:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Advertise a default route to a
peer or peer group. peer { group-name |
ip-address }
default-route-advertise [ route-policy
route-policy-name ] Not advertised by
default.
Configuring BGP route distribution/reception filtering policies
Configuration prerequisites
Configure following filters as needed:
•
ACL
• IP prefix list
• Routing policy
• AS-path ACL
For how to configure an ACL, see ACL and QoS Configuration Guide .
For how to configure an IP prefix list, routing policy, and AS-path ACL, see Configuring routing policies.
Configuring BGP route distribution filtering policies
Step Command Remarks
1. Enter system view.
system-view N/A
2.
Enter BGP view.
bgp as-number N/A
208
Step Command Remarks
3. Configure BGP route
distribution filtering
policies.
• Configure the filtering of
redistributed routes:
filter-policy { acl-number | ip-prefix
ip-prefix-name } export [ direct | isis
process-id | ospf process-id | rip
process-id | static ]
• Reference a routing policy to filter
advertisements to a peer or peer
group:
peer { group-name | ip-address }
route-policy route-policy-name
export
• Reference an ACL to filter
advertisements to a peer or peer
group:
peer { group-name | ip-address }
filter-policy acl-number export
• Reference an AS path ACL to filter
routing information sent to a peer or
peer group:
peer { group-name | ip-address }
as-path-acl as-path-acl-number
export
• Reference an IP prefix list to filter
routing information sent to a peer or
peer group:
peer { group-name | ip-address }
ip-prefix ip-prefix-name export Configure at least one command.
Not configured by default.
You can configure a filtering policy
as needed.
If several filtering policies are
configured, they are applied in the
following sequence:
4.
filter-policy export
5. peer filter-policy export
6. peer as-path-acl export
7. peer ip-prefix export
8. peer route-policy export
Only routes passing the first policy
can go to the next, and only routes
passing all the configured policies
can be advertised.
Configuring BGP route rece ption filtering policies
Only routes permitted by the configured filtering polici es can be installed into the local BGP routing table.
The members of a peer group can have different route reception filtering policies from the peer group.
To configure BGP route reception filtering policies:
Step Command Remarks
1. Enter system view.
system-view N/A
2.
Enter BGP view.
bgp as-number N/A
209
Step Command Remarks
3. Configure BGP route
reception filtering
policies.
• Filter incoming routes with an ACL or
IP prefix list:
filter-policy { acl-number | ip-prefix
ip-prefix-name } import
• Reference a routing policy to filter
routes from a peer or peer group:
peer { group-name | ip-address }
route-policy route-policy-name
import
• Reference an ACL to filter routing
information from a peer or peer
group:
peer { group-name | ip-address }
filter-policy acl-number import
• Reference an AS path ACL to filter
routing information from a peer or
peer group:
peer { group-name | ip-address }
as-path-acl as-path-acl-number
import
• Reference an IP prefix list to filter
routing information from a peer or
peer group:
peer { group-name | ip-address }
ip-prefix ip-prefix-name import Configure at least one command.
No route reception filtering is
configured by default.
If several filtering policies are
configured, they are applied in the
following sequence:
4.
filter-policy import
5. peer filter-policy import
6. peer as-path-acl import
7. peer ip-prefix import
8. peer route-policy import
Only routes passing all the
configured policies can be received.
Enabling BGP and IGP route synchronization
By default, upon receiving an IBGP route, a BGP router checks the route’s next hop. If the next hop is
reachable, the BGP router advertises the route to EBGP peers. If the synchronization feature is configured,
in addition to the reachability check of the next hop, the BGP router must find an active IGP route with the
same destination network segment before it can advertise the IBGP route (use the display ip routing-table
protocol command to check the IGP route state).
To enable BGP and IGP synchronization:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Enable synchronization
between BGP and IGP. synchronization
Not enabled by default.
Limiting prefixes received from a peer or peer group
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
210
Step Command Remarks
3. Configure the maximum
number of prefixes allowed to
be received from a peer or
peer group.
• Specify the maximum number
of prefixes that can be received
from a peer or peer group:
peer { group-name |
ip-address } route-limit
prefix-number
[ percentage-value ]
• Specify the maximum number
of prefixes that can be received
from a peer or peer group:
peer { group-name |
ip-address } route-limit
prefix-number alert-only
[ percentage-value ]
• Specify the maximum number
of prefixes that can be received
from a peer or peer group:
peer { group-name |
ip-address } route-limit
prefix-number reconnect
reconnect-time
[ percentage-value ] Use one of the commands.
No limit is configured by default.
I
f the specified maximum number is
reached:
• For approach 1, the router
breaks down the BGP
connection to the peer.
• For approach 2, the router
outputs alert information but
does not break down the BGP
connection to the peer.
• For approach 3, the router
breaks down the BGP
connection to the peer and then
reestablishes a BGP connection
to the peer.
Configuring BGP route dampening
By configuring BGP route dampening, you can suppres s unstable routes from being added to the local
routing table or being advertised to BGP peers.
To configure BGP route dampening:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Configure BGP route
dampening. dampening
[ half-life-reachable
half-life-unreachable reuse suppress ceiling |
route-policy route-policy-name ] * Not configured by
default.
Configuring a shortcut route
An EBGP route received has a priority of 255, which is lower than a local route. This task allows you to
configure an EBGP route as a shortcut route. It has the same priority as a local route and is more likely
to become the optimal route.
To configure a shortcut route:
Step Command Remarks
1.
Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
211
Step Command Remarks
3. Configure a shortcut route. network
ip-address [ mask | mask-length ]
short-cut Optional.
By default, an EBGP
route received has a
priority of 255.
Configuring BGP route attributes
Configuration prerequisites
BGP connections must be created.
Specifying a preferred value for routes received
By default, routes received from a peer have a preferred value of 0. Among multiple routes that have the
same destination and mask and are learned from diff
erent peers, the one with the greatest preferred
value is selected as the route to the destination.
To specify a preferred value for routes from a peer or peer group:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Specify a preferred value for
routes received from a peer
or peer group. peer {
group-name | ip-address }
preferred-value value Optional.
By default, the preferred
value is 0.
Configuring preferences for BGP routes
A router can run multiple routing protocols with each having a preference. If they find the same route, the
route found by the routing protocol with the highest preference is selected.
This task allows you to configure preferences for external, internal, and local BGP routes, and reference
a routing policy to set preferences for matching routes as needed.
To configure preferences for BGP routes:
Step Command
Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Configure preferences for external,
internal, and local BGP routes. preference { external-preference
internal-preference
local-preference
| route-policy
route-policy-name } Optional.
The default preferences of
external, internal, and local
BGP routes are 255, 255,
and 130.