Juniper JUNOSE 11.2.X BGP AND MPLS, Configuration Manual

Page: 159 / 742

To force BGP to run the decision process on routes already received, you must use the
clear ip bgp command to perform an inbound soft clear or hard clear of the current
BGP session.
•
Use the no version to restore the default, where the MED is not taken into account.
Suppose a BGP speaker has three routes to prefix 10.10.0.0/16:
•
Route 1 is originated by sub-AS 1 inside the confederation.
•
Route 2 is originated by sub-AS 2 inside the confederation.
•
Route 3 is originated by AS 3 outside the confederation.
•
See bgp bestpath med confed.
BGP compares these routes to each other to determine the best path to the prefix. If you
have issued the
bgp bestpath med confed command, BGP takes into account the MED
when comparing Route 1 with Route 2. However, BGP does not take into account the
MED when comparing Route 3 with either Route 1 or Route 2, because Route 3 originates
outside the confederation.
Capability Negotiation
The router accepts connections from peers that perform capability negotiation.
Capabilities are negotiated by means of the open messages that are exchanged when
the session is established. The router supports the following capabilities:
•
Cisco-proprietary route refresh—Capability code 128
•
Cooperative route filtering—Capability code 3
• Deprecated dynamic capability negotiation—Capability code 66
• Dynamic capability negotiation—Capability code 67
•
Four-octet AS numbers—Capability code 65
•
Graceful restart—Capability code 64
• Multiprotocol extensions—Capability code 1
• address family IPv4 unicast—AFI 1 SAFI 1
•
address family IPv4 multicast—AFI 1 SAFI 2
• address family IPv4 unicast and multicast—AFI 1 SAFI 3
• address family VPN-IPv4 unicast—AFI 1 SAFI 128
•
Route refresh—Capability code 2
The router advertises these capabilities—except for the cooperative route filtering
capability—by default. You can prevent the advertisement of specific capabilities with
the
no neighbor capability command. You can also use this command to prevent all
capability negotiation with the specified peer.
123 Copyright © 2010, Juniper Networks, Inc.
Chapter 1: Configuring BGP Routing