Information Technology Reference
In-Depth Information
Here are some of the capabilities that are supported in Cisco IOS software:
•
Capability code 1, Multiprotocol extension
•
Capability code 2, Route refresh
•
Capability code 64, Graceful restart
•
Capability code 128, Old form of route refresh
•
Capability code 130, Outbound Route Filter (ORF)
The subject of multiprotocol BGP is covered in Chapter 10 through Appendix A. Route
refresh, graceful restart, and ORF are covered in Chapter 3, “Tuning BGP Performance.”
To support addresses other than IPv4, various address families (AFs) are defined (RFC
1700). Examples of supported address families are IPv4 and IPv6. Within each address
family, subsequent address family identifiers (SAFIs) are further defined. Within the IPv4
address family, for example, the following SAFIs are defined:
•
Unicast, SAFI code 1
•
Multicast, SAFI code 2
•
IPv4 Label, SAFI code 4
•
Labeled VPNv4 Unicast, SAFI code 128
Within each supported capability, a peer may advertise the AFs and SAFIs that are
supported. Only the common capabilities are used during session setup.
Example 2-3 shows an example of BGP capabilities as part of the
show ip bgp neighbor
output. Four capabilities are exchanged (advertised and received): route refresh (both old
and new forms), IPv4 Unicast, IPv4 Label, and IPv4 ORF (shown under IPv4 address
family).
Example of BGP Capabilities
Example 2-3
router#show ip bgp neighbor
|
begin cap
Neighbor capabilities:
Route refresh: advertised and received(old & new)
Address family IPv4 Unicast: advertised and received
IPv4 MPLS Label capability: advertised and received
Received 1355 messages, 0 notifications, 0 in queue
Sent 1354 messages, 0 notifications, 0 in queue
Default minimum time between advertisement runs is 30 seconds
Neighbor capabilities:
For address family: IPv4 Unicast
BGP table version 5, neighbor version 5
Index 1, Offset 0, Mask 0x2
AF-dependant capabilities:
Outbound Route Filter (ORF) type (128) Prefix-list:
Send-mode: advertised, received
Receive-mode: advertised, received
For address family: IPv4 Unicast
