Users Guide

• High CPU utilization may be observed during an SNMP walk of a large BGP Loc-RIB.
• To avoid SNMP timeouts with a large-scale conguration (large number of BGP neighbors and a large BGP Loc-RIB), Dell Networking
recommends setting the timeout and retry count values to a relatively higher number. For example, t = 60 or r = 5.
• To return all values on an snmpwalk for the f10BgpM2Peer sub-OID, use the -C c option, such as snmpwalk -v 2c -C c -c
public<IP_address><OID>.
• An SNMP walk may terminate pre-maturely if the index does not increment lexicographically. Dell Networking recommends using
options to ignore such errors.
• Multiple BPG process instances are not supported. Thus, the f10BgpM2PeerInstance eld in various tables is not used to locate a peer.
• Multiple instances of the same NLRI in the BGP RIB are not supported and are set to zero in the SNMP query response.
• The f10BgpM2NlriIndex and f10BgpM2AdjRibsOutIndex elds are not used.
• Carrying MPLS labels in BGP is not supported. The f10BgpM2NlriOpaqueType and f10BgpM2NlriOpaquePointer elds are set to zero.
• 4-byte ASN is supported. The f10BgpM2AsPath4byteEntry table contains 4-byte ASN-related parameters based on the conguration.
• If a received update route matches with a local prex, then that route is discarded. This behavior results from an incorrect BGP
conguration. To overcome this issue, you can trigger a route refresh after you properly congure BGP.
Traps (notications) specied in the BGP4 MIB draft <draft-ietf-idr-bgp4–mibv2–05.txt> are not supported. Such traps
(bgpM2Established and bgpM2BackwardTransition) are supported as part of RFC 1657.
Conguration Information
The software supports BGPv4 as well as the following:
• deterministic multi-exit discriminator (MED) (default)
• a path with a missing MED is treated as worst path and assigned an MED value of (0x)
• the community format follows RFC 1998
• delayed conguration (the software at system boot reads the entire conguration le prior to sending messages to start BGP peer
sessions)
The following are not yet supported:
• auto-summarization (the default is no auto-summary)
• synchronization (the default is no synchronization)
BGP Conguration
To enable the BGP process and begin exchanging information, assign an AS number and use commands in ROUTER BGP mode to
congure a BGP neighbor.
By default, BGP is disabled.
By default, Dell Networking OS compares the MED attribute on dierent paths from within the same AS (the bgp always-compare-
med
command is not enabled).
NOTE
: In Dell Networking OS, all newly congured neighbors and peer groups are disabled. To enable a neighbor or peer group,
enter the neighbor {ip-address | peer-group-name} no shutdown command.
The following table displays the default values for BGP on Dell Networking OS.
Table 10. BGP Default Values
Item Default
BGP Neighbor Adjacency changes All BGP neighbor changes are logged.
Fast External Fallover feature Disabled
Graceful Restart feature Disabled
Border Gateway Protocol IPv4 (BGPv4) 171