THEORY
BGP overview
AS & ASN
Types of ASN
Why we use BGP?
» Traffic flow in IGP
» Traffic Flow in BGP
When to use BGP
When no to use BGP
BGP limitation
BGP Tables
Types of BGP peer or speaker
Single homed
Multi homed
Transit AS
BGP neighbor discovery
Establishing a BGP session
How to configure IBGP & EBGP peer
When BGP peering fails
» Neighbor is reachable but TCP port 179 is blocked
» Neighbor not reachable
» Neighbor not configured
» ASN mismatched
BGP update source loopback
BGP multi-hopBGP authentication
BGP aggregation
BGP proxy aggregation
BGP next-hop-self
BGP classful network advertisement
BGP classless network advertisement
BGP Synchronization Rule
IBGP split horizon
BGP Message type
» Open Message
» Keep alive Message
» Update Message
» Notification Message
NLRI
BGP FSM(Finite-State-Machine)
» Idle, Connect , Active ,Open Sent ,Open Confirm ,Established
BGP Attributes
» Well-known Attributes
» Well-Known Mandatory
- Origin
- Next-hop
- AS-Path
» Well-Known Discretionary
- Local PreferenceA
- Atomic aggregate
» Optional Attributes
» Transitive Optional Attributes
- Aggregator
- Community
» Non Transitive Optional Attributes
- MED
- Originator ID
- Cluster-List
BGP Path attributes MAP
BGP Path Selection Process
AS path filteringPrefix-list Vs ACL
OUTBOUND Route filtering
Route-map with match & set statements
Hard & soft reset
Soft reconfiguration & route refresh
Soft reconfiguration & memory uses
Inbound & outbound soft reconfiguration
Next-hop attribute point-to-pointNext-hop attribute BMA
Next-hop attribute NBMA
BGP route selection with weight per neighbor
Weight with route-map
BGP local preference
Default local preferenceLocal preference with route map
Route selection with Local preference
Monitoring Local preference AS path-prepending
Return Path selection in multi As
Default return path
Proper return path
Monitoring As-Path prepending
BGP multi-exit Discriminator
Selecting the proper return path with MED
Default MED
Advance MED conceptMonitoring MED
BGP Communities
» Internet
» No-Export
» No-Advertise
» Local-AS
» None
How to define Own Community ?
BGP communities with route-map
Monitoring communities
Procedure for Own Community-list
Customer to provider connectivity with BGP
» Single permanent connection to the internet
» Multiple permanent connection provides redundancy
» Multiple permanent connection providing load sharing
» Multiple connection to multiple service provider
IP addressing requirement for single homed customer
IP address requirement for multi-homed customer
ASN allocation to single homed customer
ASN allocation to multi-homed customer
Removing private ASN Primary & Backup link selection
ASN Translation
BGP incoming traffic selection policy using own community list
Transit AS
Internal route propagation
Packet forwarding in an ASI
BGP split horizon
IBGP Full Mesh
Recursive lookup in Cisco IOS
IBGP required IGP
IBGP session with loopback
IBGP synchronization
Drawback of logical Full mesh
Introduction to Confederation
» Splitting a Transit AS with BGP confederation
» AS-Path propagation with in the BGP confederation
» Intra confederation IBGP session properties
» Monitoring confederation
Route-Reflector
» Router-Reflector
- Client
- Non-client
» Redundant Route-Reflector
- Originator ID
- Cluster ID
BGP Optimization
BGP convergence time reduction or improving
BGP convergence
» BGP routing process
BGP open
BGP input/output
BGP scanner
- High CPU due to BGP scanner process
BGP router
- High CPU due to BGP router process
Max path transmission unit discovery & monitoring
Increasing the input hold queue
- How to improve BGP input queue & its monitoring?
BGP scan time
- How to change scan time & its monitoring?
BGP Advertisement interval
- How to change BGP advertisement interval & its monitoring?
Limiting no. of prefix receive from a BGP neighbor (Maximum , threshold, Warning-only ,Restart)
Monitoring the BGP max-prefix function
BGP Peer Groups
» Peer group requirement
» Peer group as a BGP performance tool
» BGP peer group limitation
» Monitoring BGP peer group
BGP Route Dampening
BGP route dampening operation
BGP route Dampening components
» Flap
» History state
» Penalty
» Damp state
» Suppress limit
» Half-life
» Reuse-limit
»Max suppress limit
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