BigIron RX Series Configuration Guide
679
53-1001810-01
Overview of OSPF (Open Shortest Path First)
25
Figure 104
shows an example of the AS External LSA reduction feature. In this example, Routers D
and E are OSPF ASBRs, and thus communicate route information between the OSPF AS, which
contains Routers A, B, and C, and another routing domain, which contains Router F. The other
routing domain is running another routing protocol, such as BGP4 or RIP. Routers D, E, and F,
therefore, are each running both OSPF and either BGP4 or RIP.
FIGURE 104
AS external LSA reduction
Notice that both Router D and Router E have a route to the other routing domain through Router F.
OSPF eliminates the duplicate AS External LSAs. When two or more BigIron RX switches are
configured as ASBRs have equal-cost routes to the same next-hop router in an external routing
domain, the ASBR with the highest router ID floods the AS External LSAs for the external domain
into the OSPF AS, while the other ASBRs flush the equivalent AS External LSAs from their
databases. As a result, the overall volume of route advertisement traffic within the AS is reduced
and the device switches that flush the duplicate AS External LSAs have more memory for other
OSPF data. In
Figure 104
, since Router D has a higher router ID than Router E, Router D floods the
AS External LSAs for Router F to Routers A, B, and C. Router E flushes the equivalent AS External
LSAs from its database.
Router B
Router A
Router C
Router D
Router ID: 2.2.2.2
OSPF Autonomous System (AS)
Router E
Router ID: 1.1.1.1
Routers D, E, and F
are OSPF ASBRs
and EBGP routers.
Another routing domain
(such as BGP4 or RIP)
Router F
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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Страница 1436: ...1364 BigIron RX Series Configuration Guide 53 1001810 01 VSRP E ...