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BigIron RX Series Configuration Guide
53-1001810-01
Overview of OSPF (Open Shortest Path First)
25
NOTE
By default, the Brocade router ID is the IP address configured on the lowest numbered loopback
interface. If the BigIron RX does not have a loopback interface, the default router ID is the lowest
numbered IP address configured on the device. For more information or to change the router ID,
refer to
“Changing the router ID”
on page 174.
When multiple routers on the same network are declaring themselves as DRs, then both priority
and router ID are used to select the designated router and backup designated routers.
When only one router on the network claims the DR role despite neighboring routers with higher
priorities or router IDs, this router remains the DR. This is also true for BDRs.
The DR and BDR election process is performed when one of the following events occurs:
•
an interface is in a waiting state and the wait time expires
•
an interface is in a waiting state and a hello packet is received that addresses the BDR
•
a change in the neighbor state occurs, such as:
•
a neighbor state transitions from ATTEMPT state to a higher state
•
communication to a neighbor is lost
•
a neighbor declares itself to be the DR or BDR for the first time
OSPF RFC 1583 and 2328 compliance
Brocade routers are configured, by default, to be compliant with the RFC 1583 OSPF V2
specification. Brocade routers can also be configured to operate with the latest OSPF standard,
RFC 2328.
NOTE
For details on how to configure the system to operate with the RFC 2328, refer to
“Modify OSPF
standard compliance setting”
on page 716.
Reduction of equivalent AS external LSAs
An OSPF ASBR uses AS External link advertisements (AS External LSAs) to originate advertisements
of a route learned from another routing domain, such as a BGP4 or RIP domain. The ASBR
advertises the route to the external domain by flooding AS External LSAs to all the other OSPF
routers (except those inside stub networks) within the local OSPF Autonomous System (AS).
In some cases, multiple ASBRs in an AS can originate equivalent LSAs. The LSAs are equivalent
when they have the same cost, the same next hop, and the same destination. The device optimizes
OSPF by eliminating duplicate AS External LSAs in this case. The device with the lower router ID
flushes the duplicate External LSAs from its database and thus does not flood the duplicate
External LSAs into the OSPF AS. AS External LSA reduction therefore reduces the size of the BigIron
RX’s link state database. The AS External LSA reduction is described in RFC 2328
Содержание Brocade DCX
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Страница 88: ...16 BigIron RX Series Configuration Guide 53 1001810 01 Searching and filtering output 1 ...
Страница 300: ...228 BigIron RX Series Configuration Guide 53 1001810 01 Displaying IP information 7 ...
Страница 318: ...246 BigIron RX Series Configuration Guide 53 1001810 01 Deploying a LAG 8 ...
Страница 418: ...346 BigIron RX Series Configuration Guide 53 1001810 01 SuperSpan 12 ...
Страница 482: ...410 BigIron RX Series Configuration Guide 53 1001810 01 MRP CLI example 14 ...
Страница 506: ...434 BigIron RX Series Configuration Guide 53 1001810 01 Displaying VSRP information 15 ...
Страница 566: ...494 BigIron RX Series Configuration Guide 53 1001810 01 QoS for the oversubscribed 16 x 10GE modules 18 ...
Страница 582: ...510 BigIron RX Series Configuration Guide 53 1001810 01 Viewing Layer 2 ACLs 20 ...
Страница 634: ...562 BigIron RX Series Configuration Guide 53 1001810 01 Troubleshooting ACLs 21 ...
Страница 642: ...570 BigIron RX Series Configuration Guide 53 1001810 01 Trunk formation 22 ...
Страница 746: ...674 BigIron RX Series Configuration Guide 53 1001810 01 Displaying RIP filters 24 ...
Страница 808: ...736 BigIron RX Series Configuration Guide 53 1001810 01 Displaying OSPF information 25 ...
Страница 926: ...854 BigIron RX Series Configuration Guide 53 1001810 01 Generalized TTL security mechanism support 26 ...
Страница 938: ...866 BigIron RX Series Configuration Guide 53 1001810 01 Displaying MBGP information 27 ...
Страница 950: ...878 BigIron RX Series Configuration Guide 53 1001810 01 Using secure copy 28 ...
Страница 988: ...916 BigIron RX Series Configuration Guide 53 1001810 01 Clearing IS IS information 29 ...
Страница 998: ...926 BigIron RX Series Configuration Guide 53 1001810 01 Configuring BFD for the specified protocol 30 ...
Страница 1014: ...942 BigIron RX Series Configuration Guide 53 1001810 01 Displaying multi device port authentication information 31 ...
Страница 1054: ...982 BigIron RX Series Configuration Guide 53 1001810 01 Sample 802 1x configurations 33 ...
Страница 1072: ...1000 BigIron RX Series Configuration Guide 53 1001810 01 IP source guard 35 Syntax show ip source guard ethernet port num ...
Страница 1108: ...1036 BigIron RX Series Configuration Guide 53 1001810 01 sFlow 39 ...
Страница 1190: ...1118 BigIron RX Series Configuration Guide 53 1001810 01 Displaying RIPng information 44 ...
Страница 1270: ...1198 BigIron RX Series Configuration Guide 53 1001810 01 Displaying ACLs 47 ...
Страница 1310: ...1238 BigIron RX Series Configuration Guide 53 1001810 01 Displaying OSPFv3 information 48 ...
Страница 1382: ...1310 BigIron RX Series Configuration Guide 53 1001810 01 Commands That Require a Reload D ...
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