RE: bgp advertising rules

Hi Mosttafa,

Sorry didn't spend that much time on your snippet but as a rule of thumb in
BGP you should have at least one component before aggregating them, you should
have a trace of it in your routing table before advertising it as BGP route
(e.g. static route, loopback etc.) and finally you should have your next hop
fully reachable before importing it into your routing table from your BGP
table....

Hence you can not summarize something which you dont own even a piece of it ;)
which makes sense. Doesn't it?

--------------------------
Kambiz Agahian
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-----Original Message-----
From: nobody_at_groupstudy.com on behalf of Mustafa Yadav
Sent: Sun 4/25/2010 5:48 AM
To: Cisco certification
Subject: bgp advertising rules

hi guys

my config as shown below did not advertise anything up to when I added a
network statement net 132.1.17.0 mask 255.255.255.0 under bgp.Why is
that?Is there any spesific rule for advertising aggreagate route ?On the
other hand for recap can someone write it down what are general rules for
advertising in bgp?

Many thanks

RSRack1SW1#sh
*Mar 1 03:54:36.227: %SYS-5-CONFIG_I: Configured from console by console
RSRack1SW1#sh run | s bgp
router bgp 400
 no synchronization
 bgp router-id 150.1.7.7
 bgp log-neighbor-changes
 aggregate-address 132.1.0.0 255.255.0.0 summary-only
 neighbor 132.1.17.1 remote-as 300
 neighbor 204.12.1.8 remote-as 400
 neighbor 204.12.1.254 remote-as 54
 neighbor 204.12.1.254 local-as 100 no-prepend
 no auto-summary
RSRack1SW1#sh ip bgp neighbors 204.12.1.254 advertised-routes
Total number of prefixes 0
RSRack1SW1#sh ip ro
RSRack1SW1#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static
route
       o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
B 119.0.0.0/8 [20/0] via 204.12.1.254, 00:30:47
B 118.0.0.0/8 [20/0] via 204.12.1.254, 00:30:47
C 204.12.1.0/24 is directly connected, Vlan783
B 117.0.0.0/8 [20/0] via 204.12.1.254, 00:30:47
B 116.0.0.0/8 [20/0] via 204.12.1.254, 00:30:47
     132.1.0.0/16 is variably subnetted, 13 subnets, 2 masks
O IA 132.1.255.0/24 [110/66] via 132.1.17.1, 02:09:19, FastEthernet1/1
O E2 132.1.5.0/24 [110/20] via 132.1.17.1, 02:09:14, FastEthernet1/1
O IA 132.1.0.4/32 [110/65] via 132.1.17.1, 02:09:19, FastEthernet1/1
O IA 132.1.0.1/32 [110/1] via 132.1.17.1, 02:09:49, FastEthernet1/1
O IA 132.1.3.0/24 [110/66] via 132.1.17.1, 02:09:28, FastEthernet1/1
O IA 132.1.0.3/32 [110/65] via 132.1.17.1, 02:09:29, FastEthernet1/1
O IA 132.1.0.2/32 [110/65] via 132.1.17.1, 02:09:39, FastEthernet1/1

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Received on Sun Apr 25 2010 - 11:25:05 ART