Dynamic routing protocols can be divided into two kinds of IGP and EGP
IGP into RIP ospf IS-IS
BGP Border Gateway Protocol
BGP is an EGP, the work between the AS and AS
AS (Autonomous System)
AS may be a company to run a business a large organization, a university
internal AS routing protocols ----- IGP
routing protocol between EGP ----- AS
BGP itself is a multi-protocol address family (MP-BGP, multi-protocol BGP) - - address family (ipv4, ipv6's)
Wherein BGP
BGP is an external routing protocol for passing routing information between AS
is an enhanced distance vector routing protocol
reliable route update mechanism
rich Metric measurement method
avoids the generation of a loop from the design
of the routing attribute information incidental
support CIDR (classless inter-domain routing)
rich route filtering and routing policy
RIP uses distance vector protocols hop (hop = router)
distance-vector protocol BGP uses the number (AS BY AS) hop
on tcp port number 179 means that across update the routing device
does not periodically update, only incremental updates since BGP routing table is too large
NA hello packets to maintain keepAlive but the use of TCP connectivity check messages
BGP packets species
Open (their ability to carry information, RID and so on to the end, to establish BGP neighbor)
Keepalive (TCP remain active, prove the existence of a neighbor)
Update (updating and revocation NLRI (Network Layer Network unreachable message ---- prefix, including a wealth of routing attributes))
the Notification (error messages, if BGP detected notification, it will reset TCP connections)
refresh (BGP route refresh capability)
BGP state machine
Idle ----- Connect ----- open-sent ----- open-confirm ----- Estabished normal line
of three common state machine
Idle Active Established
IBGP: internal bgp (same AS number)
the EBGP: External BGP (different AS number)
BGP database
1. Establish neighbor relationships
2. Update of BGP detabase
3. In detabase by certain principles into the best routing table (rib)
Processing the BGP routing information
from the principles of the update information received from peer routing ---------- input RiB (Huawei 13) --- ------- into the local routing database (BGP table) --------- load routing tables
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notice to neighbors