From: Lyndon Guo (lyndon@vip.sina.com)
Date: Wed Sep 25 2002 - 03:24:54 GMT-3
hi,all
I have question of ospf. Somebody give me some advice.thank you.
if a router in the ospf area 0 and get two path to one network, and the metirc-type are E2, I like the following.
Cisco2509#show ip ospf database external
OSPF Router with ID (172.16.7.5) (Process ID 250)
Type-5 AS External Link States
Routing Bit Set on this LSA
LS age: 1315
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 10.0.0.0 (External Network Number )
Advertising Router: 192.168.1.1
LS Seq Number: 80000002
Checksum: 0x8513
Length: 36
Network Mask: /8
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 400
LS age: 1038
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 10.0.0.0 (External Network Number )
Advertising Router: 211.99.188.1
LS Seq Number: 80000001
Checksum: 0xE32C
Length: 36
Network Mask: /8
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 400
and ths external link states is like:
Cisco2509#show ip ospf database
.....
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
10.0.0.0 192.168.1.1 1679 0x80000002 0x8513 400
10.0.0.0 211.99.188.1 1402 0x80000001 0xE32C 400
192.168.2.0 192.168.1.1 1679 0x80000002 0x40F6 400
192.168.2.0 211.99.188.1 1402 0x80000001 0x9E10 400
192.168.3.0 192.168.1.1 1679 0x80000002 0x3501 400
192.168.3.0 211.99.188.1 1402 0x80000001 0x931A 400
192.168.69.0 192.168.1.1 1680 0x80000002 0x5C97 400
192.168.69.0 211.99.188.1 1403 0x80000001 0xBAB0 400
211.99.186.0 192.168.1.1 1680 0x80000002 0x9719 400
the route table is:
Cisco2509#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
1.0.0.0/30 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Serial1
172.16.0.0/24 is subnetted, 3 subnets
C 172.16.6.0 is directly connected, Loopback0
C 172.16.7.0 is directly connected, Loopback1
C 172.16.1.0 is directly connected, Ethernet0
211.99.188.0/32 is subnetted, 1 subnets
O IA 211.99.188.1 [110/65] via 1.1.1.1, 00:24:13, Serial1
O E2 10.0.0.0/8 [110/20] via 172.16.1.1, 00:24:13, Ethernet0
192.168.0.0/32 is subnetted, 1 subnets
O 192.168.0.1 [110/11] via 172.16.1.1, 00:24:13, Ethernet0
192.168.1.0/32 is subnetted, 1 subnets
O IA 192.168.1.1 [110/11] via 172.16.1.1, 00:24:14, Ethernet0
O E2 192.168.69.0/24 [110/20] via 172.16.1.1, 00:24:14, Ethernet0
O E2 192.168.2.0/24 [110/20] via 172.16.1.1, 00:24:14, Ethernet0
211.99.187.0/32 is subnetted, 1 subnets
O IA 211.99.187.1 [110/65] via 1.1.1.1, 00:24:14, Serial1
O E2 192.168.3.0/24 [110/20] via 172.16.1.1, 00:24:14, Ethernet0
O E2 211.99.186.0/24 [110/20] via 172.16.1.1, 00:24:14, Ethernet0
OK.
question 1. we can get the infomation that to network 10.0.0.0/8 there are to path: 192.168.1.1 and 211.99.188.1
and this two path's metric-type are E2, and the metric are all 20. How OSPF to choice the best path?
question 2. If one path is E1,and other is E2, and the total metric are same metric(You know,the E1 will plus the local metric) , Which path is the best one ?
Thank you...
Email:lyndon@vip.sina.com
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