TCPIPVolume2-BGP-20101217

Administrative Weight
     The weight is a number between 0 and 65535 that can be assigned to a route,the higher the weight ,the more preferable the route.
     By default, all routes learned from a peer have a weight of 0,and all routes generated by the local router have a weight of 32768.
     The weight can be set for individual routes,or for routes learned from a specific neighbor.
     This preference is entirely local to the single router,weights are not included in the BGP updates or in any other way communicated to the BGP speaker's peer.

AS_SET (2 types of AS_PASH{AS_SEQUENCE;AS_SET;AS_CONFED_SEQUENCE;AS_CONFED_SET})
     This is an unordered list of the AS numbers along a path to a destination.
     When an AS_SET is included in an AS_PATH,the ATOMIC_AGGREGATE does not have to be included with the aggregate.

 

The BGP Decision Process

…………………………略

 

Route Dampening
     Penalty——1000 per flap
     Suppress limit——2000
     Reuse limit——750
     Half-life——15 minutes
     Maximum suppress time——60 minutes,or 4 times the half-life

 

Managing Large-Scale BGP Peering
     ○Peer groups
     ○Communities
     ○Route reflectors
           ●If the route was learned from a nonclient IBGP peer,it is reflected to clients only.
           ●If the route was learned from a client ,it is reflected to all nonclients and clients,except for the originating client.
           ●If the route was learned from an EBGP peer,it is reflected to all clients and nonclients.
     ○Confederations

 

BGP Message Formats (Header Type field:1、Open.2、Update.3、Notification.4、Keepalive.)
     ●The Open Message
            __________ __________ __________ __________
           |  ……    |  ……    |  ……    | version  | 
            ——————————————————————          
           |     My AS System    |      Hold  Time     | 
            ——————————————————————  
           |                BGP   Identifier           | 
            ——————————————————————  
           |OptParalen|       Optional Parameters      |  
            —————————————————————— 
           |            Optional Parameters            | 
            —————————————————————— 
           |                                           |  
            ——————————————————————  
           |                                           | 
            ——————————————————————  
           |                                           |  
            ——————————————————————

     ●The Update Message
            —————————————————————— 
           |    Unfeasible Routes Length (2 octets)    |  
            ——————————————————————  
           |        Withdrawn Routes (variable)        | 
            ——————————————————————  
           |   Total Path Attribute Length (2 octets)  |  
            ——————————————————————
           |        Path Attributes (variable)         |  
            ——————————————————————  
           |              NLRI (variable)              | 
            ——————————————————————  
           |                                           |  
            ——————————————————————
     ●The Keepalive Message
           The Keepalive message consists of only the 19-octet BGP message header, with no additional data.
     ●The Notification Message
            ——————————————————————  
           |Error Code|ErrSubcode|                     |  
            ———————————
           |                    Data                   |  
            ——————————————————————