Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.14.1.0 - Page 190

Figure 23. Before and After AS Number Migration with Local-AS Enabled When you complete your migration, and you have reconfigured your network with the new information, disable this feature. If you use the "no prepend" option, the Local-AS does not prepend to the updates received from the eBGP peer. If you do not select "no prepend" (the default), the Local-AS is added to the first AS segment in the AS-PATH. If an inbound route-map is used to prepend the aspath to the update from the peer, the Local-AS is added first. For example, consider the topology described in the previous illustration. If Router B has an inbound route-map applied on Router C to prepend "65001 65002" to the as-path, the following events take place on Router B: 1 Receive and validate the update. 2 Prepend local-as 200 to as-path. 3 Prepend "65001 65002" to as-path. Local-AS is prepended before the route-map to give an impression that update passed through a router in AS 200 before it reached Router B. BGP4 Management Information Base (MIB) The FORCE10-BGP4-V2-MIB enhances support for BGP management information base (MIB) with many new simple network management protocol (SNMP) objects and notifications (traps) defined in draft-ietf-idr-bgp4-mibv2-05. To see these enhancements, download the MIB from the Dell website. NOTE: For the Force10-BGP4-V2-MIB and other MIB documentation, refer to the Dell iSupport web page. Important Points to Remember • Because eBGP packets are not controlled by the ACL, packets from BGP neighbors cannot be blocked using the deny ip command. • The f10BgpM2AsPathTableEntry table, f10BgpM2AsPathSegmentIndex, and f10BgpM2AsPathElementIndex are used to retrieve a particular ASN from the AS path. These indices are assigned to the AS segments and individual ASN in each segment starting from 0. 190 Border Gateway Protocol version 4 (BGPv4)