Use the attribute-filter group command to enter Attribute-filter group command mode. Use the attribute
command in attribute-filter group command mode to either discard an attribute or treat the update message
as a "Withdraw" action.
BGP Error Handling and Attribute Filtering Syslog Messages
When a router receives a malformed update packet, an ios_msg of type
ROUTING-BGP-3-MALFORM_UPDATE is printed on the console. This is rate limited to 1 message per
minute across all neighbors. For malformed packets that result in actions "Discard Attribute" (A5) or "Local
Repair" (A6), the ios_msg is printed only once per neighbor per action. This is irrespective of the number of
malformed updates received since the neighbor last reached an "Established" state.
This is a sample BGP error handling syslog message:
%ROUTING-BGP-3-MALFORM_UPDATE : Malformed UPDATE message received from neighbor 13.0.3.50
- message length 90 bytes,
error flags 0x00000840, action taken "TreatAsWithdraw".
Error details: "Error 0x00000800, Field "Attr-missing", Attribute 1 (Flags 0x00, Length 0),
Data []"
This is a sample BGP attribute filtering syslog message for the "discard attribute" action:
[4843.46]RP/0/0/CPU0:Aug 21 17:06:17.919 : bgp[1037]: %ROUTING-BGP-5-UPDATE_FILTERED :
One or more attributes were filtered from UPDATE message received from neighbor 40.0.101.1
- message length 173 bytes,
action taken "DiscardAttr".
Filtering details: "Attribute 16 (Flags 0xc0): Action "DiscardAttr"". NLRIs: [IPv4 Unicast]
88.2.0.0/17
This is a sample BGP attribute filtering syslog message for the "treat-as-withdraw" action:
[391.01]RP/0/0/CPU0:Aug 20 19:41:29.243 : bgp[1037]: %ROUTING-BGP-5-UPDATE_FILTERED :
One or more attributes were filtered from UPDATE message received from neighbor 40.0.101.1
- message length 166 bytes,
action taken "TreatAsWdr".
Filtering details: "Attribute 4 (Flags 0xc0): Action "TreatAsWdr"". NLRIs: [IPv4 Unicast]
88.2.0.0/17
BGP Link-State
BGP Link-State (LS) is an Address Family Identifier (AFI) and Sub-address Family Identifier (SAFI) defined
to carry interior gateway protocol (IGP) link-state database through BGP. BGP LS delivers network topology
information to topology servers and Application Layer Traffic Optimization (ALTO) servers. BGP LS allows
policy-based control to aggregation, information-hiding, and abstraction. BGP LS supports IS-IS and OSPFv2.
IGPs do not use BGP LS data from remote peers. BGP does not download the received BGP LS data to
any other component on the router.
Note
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.1.x
72 OL-30423-03
Implementing BGP
BGP Error Handling and Attribute Filtering Syslog Messages
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