HPE FlexNetwork 5510 HI Series Layer 3 - Ip Routing Configuration Guide

182
• Extended community attribute
To meet new demands, BGP defines the extended community attribute. The extended
community attribute has the following advantages over the COMMUNITY attribute:
{ Provides more attribute values by extending the attribute length to eight bytes.
{ Allows for using different types of extended community attributes in different scenarios to
enhance route filtering and control and simplify configuration and management.
Currently, the device supports the Route-Target attribute for VPN and Site of Origin (SoO)
attribute. For more information, see MPLS Configuration Guide.
BGP route selection
BGP discards routes with unreachable NEXT_HOPs. If multiple routes to the same destination are
available, BGP selects the optimal route in the following sequence:
1. The route with the highest Preferred_value.
2. The route with the highest LOCAL_PREF.
3. The route generated by the network command, the route redistributed by the import-route
command, or the summary route in turn.
4. The route with the shortest AS_PATH.
5. The IGP, EGP, or INCOMPLETE route in turn.
6. The route with the lowest MED value.
7. The route learned from EBGP, confederation EBGP, confederation IBGP, or IBGP in turn.
8. The route with the smallest next hop metric.
9. The route with the shortest CLUSTER_LIST.
10. The route with the smallest ORIGINATOR_ID.
11. The route advertised by the router with the smallest router ID.
12. The route advertised by the peer with the lowest IP address.
The CLUSTER_IDs of route reflectors form a CLUSTER_LIST. If a route reflector receives a route
that contains its own CLUSTER ID in the CLUSTER_LIST, the router discards the route to avoid
routing loops.
If load balancing is configured, the system selects available routes to implement load balancing.
BGP route advertisement rules
BGP follow these rules for route advertisement:
• When multiple feasible routes to a destination exist, BGP advertises only the optimal route to its
peers. If the advertise-rib-active command is configured, BGP advertises the optimal route in
the IP routing table. If not, BGP advertises the optimal route in the BGP routing table.
• BGP advertises only routes that it uses.
• BGP advertises routes learned from an EBGP peer to all BGP peers, including both EBGP and
IBGP peers.
• BGP advertises routes learned from an IBGP peer to EBGP peers, rather than other IBGP
peers.
• After establishing a session with a new BGP peer, BGP advertises all the routes matching the
above rules to the peer. After that, BGP advertises only incremental updates to the peer.
BGP load balancing
BGP implements load balancing through route recursion and route selection.

HPE FlexNetwork 5510 HI Series Specifications

General

Brand	HPE
Model	FlexNetwork 5510 HI Series
Category	Switch
Language	English