From: Brian McGahan (brian@cyscoexpert.com)
Date: Sun Feb 02 2003 - 03:48:29 GMT-3
Jason,
By default, iBGP learned prefixes cannot be redistributed into
IGP. One of the reasons behind this restriction is the mismatch in
administrative distance. iBGP has an AD of 200, which is greater than
all IGPs. If you redistribute iBGP into IGP, all other routers running
IGP and iBGP will start routing the prefix through IGP. At a minimum,
you will most likely achieve sub-optimal routing. Worst case scenario,
you will black hole traffic destined for this prefix.
If you want to change this default behavior, and allow
redistribution of iBGP into IGP, use the BGP subcommand "bgp
redistribute-internal"
For more info:
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_
summary_chapter09186a008007fc7f.html#1173923
http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_command_
reference_chapter09186a008010a396.html#1221040
HTH
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
Voice: 847.674.3392
Fax: 847.674.2625
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Jason Cash
> Sent: Saturday, February 01, 2003 11:30 PM
> To: ccielab@groupstudy.com
> Subject: CCBootcamp Lab 8 - BGP redist. into OSPF
>
> Ok, I am at my wits end on this one.I am having a problem with
> redistribution on R7 with BGP into OSPF. The BGP table shows that I
> have 7 routes as does the Route table:
>
> R7#sb
> BGP table version is 8, local router ID is 200.200.200.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 137.20.10.0/24 0.0.0.0 0 32768 i
> *>i137.20.80.0/24 137.20.64.6 0 100 0 1 i
> *>i137.20.81.0/24 137.20.64.6 0 100 0 1 i
> *>i137.20.82.0/24 137.20.64.6 0 100 0 1 i
> *>i137.20.86.0/24 137.20.64.6 0 100 0 i
> *> 172.168.70.0/24 137.20.10.70 170 0 3 i
> *>i172.168.80.0/24 137.20.64.6 0 100 0 1 i
>
> R7#sh ip ro
>
> C 200.200.200.0/24 is directly connected, Loopback0
> 137.20.0.0/16 is variably subnetted, 16 subnets, 5 masks
> O E1 137.20.200.16/28 [110/164] via 137.20.25.2, 00:18:40,
Serial1/5
> O IA 137.20.240.1/32 [110/65] via 137.20.25.2, 00:18:40, Serial1/5
> O IA 137.20.30.0/24 [110/138] via 137.20.25.2, 00:18:40, Serial1/5
> C 137.20.25.0/24 is directly connected, Serial1/5
> O IA 137.20.20.0/24 [110/138] via 137.20.25.2, 00:18:40, Serial1/5
> C 137.20.10.0/24 is directly connected, FastEthernet3/0/0
> O E1 137.20.40.16/28 [110/164] via 137.20.25.2, 00:18:41, Serial1/5
> O IA 137.20.33.0/26 [110/129] via 137.20.25.2, 00:18:41, Serial1/5
> B 137.20.86.0/24 [200/0] via 137.20.64.6, 00:03:44
> B 137.20.81.0/24 [200/0] via 137.20.64.6, 00:03:44
> B 137.20.80.0/24 [200/0] via 137.20.64.6, 00:03:44
> B 137.20.82.0/24 [200/0] via 137.20.64.6, 00:03:44
> O IA 137.20.100.33/32 [110/128] via 137.20.25.2, 00:18:41,
Serial1/5
> O IA 137.20.100.35/32 [110/128] via 137.20.25.2, 00:18:41,
Serial1/5
> O IA 137.20.100.34/32 [110/64] via 137.20.25.2, 00:18:41, Serial1/5
> O IA 137.20.64.0/20 [110/74] via 137.20.25.2, 00:18:41, Serial1/5
> O IA 200.200.100.0/24 [110/129] via 137.20.25.2, 00:18:41, Serial1/5
> 172.168.0.0/24 is subnetted, 2 subnets
> B 172.168.70.0 [20/170] via 137.20.10.70, 00:04:02
> B 172.168.80.0 [200/0] via 137.20.64.6, 00:03:44
>
> However, when I redistribute BGP into OSPF, the above BGP routes and
not
> brought into OSPF on R5 : R7 (s2)----R5 (s1)
>
> R7
> router ospf 1
> log-adjacency-changes
> redistribute bgp 2 metric-type 2 subnets tag 7
>
> R5
> r5#si
> 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, 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
>
> 200.200.200.0/32 is subnetted, 1 subnets
> O 200.200.200.1 [110/65] via 137.20.25.1, 00:01:39, Serial0
> 137.20.0.0/16 is variably subnetted, 12 subnets, 6 masks
> C 137.20.200.16/28 is directly connected, Serial1.2
> C 137.20.240.0/20 is directly connected, Loopback0
> O 137.20.30.0/24 [110/74] via 137.20.100.35, 00:01:39, Serial1.1
> C 137.20.25.0/24 is directly connected, Serial0
> O IA 137.20.20.0/24 [110/74] via 137.20.100.33, 00:01:39, Serial1.1
> O E2 137.20.10.0/24 [110/1] via 137.20.25.1, 00:01:40, Serial0
> I 137.20.40.16/28 [100/8576] via 137.20.200.18, 00:00:29,
> Serial1.2
> O IA 137.20.33.0/26 [110/65] via 137.20.100.35, 00:01:40, Serial1.1
> O 137.20.100.33/32 [110/64] via 137.20.100.33, 00:01:40,
Serial1.1
> C 137.20.100.32/27 is directly connected, Serial1.1
> O 137.20.100.35/32 [110/64] via 137.20.100.35, 00:01:40,
Serial1.1
> C 137.20.64.0/20 is directly connected, Ethernet0
> O 200.200.100.0/24 [110/65] via 137.20.100.33, 00:01:40, Serial1.1
> 172.168.0.0/24 is subnetted, 1 subnets
> O E2 172.168.70.0 [110/1] via 137.20.25.1, 00:01:40, Serial0
>
> There are two of the routes on R5 but not the other ones listed with
an
> AD 200 on R7. What gives? I found another workaround (mutual
> redistribution on two routers) but I need to know why this doesn't
work.
> Below is the 'sh ip ospf data' on R5. Please show me the light!
>
> r5#sh ip ospf data
>
> OSPF Router with ID (137.20.240.1) (Process ID 1)
>
>
> Router Link States (Area 0)
>
> Link ID ADV Router Age Seq# Checksum Link
> count
> 137.20.33.33 137.20.33.33 1 (DNA) 0x80000005 0x7206 1
> 137.20.60.1 137.20.60.1 536 0x80000031 0xD1AA 1
> 137.20.240.1 137.20.240.1 29 0x8000003B 0xCED5 4
> 200.200.100.1 200.200.100.1 5 (DNA) 0x80000009 0x840 1
>
> Net Link States (Area 0)
>
> Link ID ADV Router Age Seq# Checksum
> 137.20.64.6 137.20.60.1 782 0x8000002C 0x9F55
>
> Summary Net Link States (Area 0)
>
> Link ID ADV Router Age Seq# Checksum
> 137.20.20.0 200.200.100.1 51 (DNA) 0x80000001 0xA80
> 137.20.25.0 137.20.240.1 1057 0x8000002C 0xA1E9
> 137.20.30.0 137.20.33.33 1 (DNA) 0x80000001 0x9007
> 137.20.30.0 137.20.240.1 1311 0x80000029 0xD4AA
> 137.20.30.0 200.200.100.1 1 (DNA) 0x80000001 0xA05F
> 137.20.33.0 137.20.33.33 1 (DNA) 0x80000001 0x9943
> 137.20.100.33 137.20.33.33 1 (DNA) 0x80000001 0xE0D8
> 137.20.100.33 137.20.240.1 545 0x8000002B 0x1C04
> 137.20.100.33 200.200.100.1 51 (DNA) 0x80000001 0xE63C
> 137.20.100.34 137.20.33.33 21 (DNA) 0x80000001 0x54A4
> 137.20.100.34 137.20.240.1 1312 0x80000029 0x93CD
> 137.20.100.34 200.200.100.1 51 (DNA) 0x80000001 0x5F82
> 137.20.100.35 137.20.33.33 21 (DNA) 0x80000001 0xC770
> 137.20.100.35 137.20.240.1 1312 0x80000029 0xC14
> 137.20.100.35 200.200.100.1 51 (DNA) 0x80000001 0xD7C8
> 200.200.100.0 137.20.33.33 1 (DNA) 0x80000001 0x875E
> 200.200.100.0 137.20.240.1 545 0x8000002B 0xC289
> 200.200.100.0 200.200.100.1 51 (DNA) 0x80000001 0x8DC1
> 200.200.200.1 137.20.240.1 545 0x8000000C 0xA65F
>
> Summary ASB Link States (Area 0)
>
> Link ID ADV Router Age Seq# Checksum
> 137.20.240.1 137.20.33.33 1 (DNA) 0x80000001 0x8705
> 137.20.240.1 200.200.100.1 1 (DNA) 0x80000001 0x92E2
> 200.200.200.1 137.20.240.1 1059 0x80000002 0xA26D
>
> Router Link States (Area 1)
>
> Link ID ADV Router Age Seq# Checksum Link
> count
> 137.20.33.33 137.20.33.33 1747 0x8000002F 0x4402 3
> 137.20.240.1 137.20.240.1 295 0x80000032 0x8976 3
> 200.200.100.1 200.200.100.1 1566 0x8000003A 0xDB04 3
>
> Summary Net Link States (Area 1)
>
> Link ID ADV Router Age Seq# Checksum
> 137.20.20.0 137.20.33.33 1501 0x80000005 0xFB21
> 137.20.20.0 137.20.240.1 549 0x80000028 0x4545
> 137.20.20.0 200.200.100.1 297 0x8000002D 0xB1AC
> 137.20.25.0 137.20.33.33 1501 0x80000005 0x60C1
> 137.20.25.0 137.20.240.1 1316 0x8000002A 0xA5E7
> 137.20.25.0 200.200.100.1 1566 0x80000027 0x27C1
> 137.20.33.0 137.20.33.33 1255 0x80000005 0x9147
> 137.20.33.0 137.20.240.1 1062 0x80000005 0x26C2
> 137.20.33.0 200.200.100.1 1065 0x80000005 0xA19F
> 137.20.64.0 137.20.33.33 1501 0x80000005 0x48F7
> 137.20.64.0 137.20.240.1 1317 0x8000002A 0x8D1E
> 137.20.64.0 200.200.100.1 1567 0x80000027 0xFF7
> 137.20.240.1 137.20.33.33 1502 0x80000005 0x97F0
> 137.20.240.1 137.20.240.1 800 0x80000029 0xDE16
> 137.20.240.1 200.200.100.1 1567 0x80000027 0x5EF0
> 200.200.200.1 137.20.33.33 1502 0x80000005 0x2557
> 200.200.200.1 137.20.240.1 550 0x8000000C 0xA65F
> 200.200.200.1 200.200.100.1 298 0x8000000C 0x223C
>
> Summary ASB Link States (Area 1)
>
> Link ID ADV Router Age Seq# Checksum
> 137.20.240.1 137.20.33.33 1502 0x80000005 0x7F09
> 137.20.240.1 200.200.100.1 1817 0x8000000B 0x7EEC
> 200.200.200.1 137.20.33.33 1256 0x80000002 0x136C
> 200.200.200.1 137.20.240.1 1063 0x80000002 0xA26D
> 200.200.200.1 200.200.100.1 1066 0x80000002 0x1E4A
>
> Router Link States (Area 2)
>
> Link ID ADV Router Age Seq# Checksum Link
> count
> 137.20.240.1 137.20.240.1 296 0x8000002D 0x810A 2
> 200.200.200.1 200.200.200.1 1154 0x8000002D 0x173E 3
>
> Summary Net Link States (Area 2)
>
> Link ID ADV Router Age Seq# Checksum
> 137.20.20.0 137.20.240.1 551 0x80000028 0x4545
> 137.20.30.0 137.20.240.1 1318 0x80000029 0xD4AA
> 137.20.33.0 137.20.240.1 1064 0x80000005 0x26C2
> 137.20.64.0 137.20.240.1 1064 0x8000002D 0x8721
> 137.20.100.33 137.20.240.1 551 0x80000028 0x2201
> 137.20.100.34 137.20.240.1 1320 0x80000029 0x93CD
> 137.20.100.35 137.20.240.1 1320 0x80000029 0xC14
> 137.20.240.1 137.20.240.1 803 0x80000029 0xDE16
> 200.200.100.0 137.20.240.1 553 0x80000028 0xC886
>
> Type-5 AS External Link States
>
> Link ID ADV Router Age Seq# Checksum Tag
> 137.20.10.0 200.200.200.1 156 0x80000001 0xA9FC 10
> 137.20.40.16 137.20.240.1 1819 0x8000000B 0xBEB1 0
> 137.20.200.16 137.20.240.1 299 0x8000000C 0xD5F8 0
> 172.168.70.0 200.200.200.1 156 0x80000001 0x535F 10
> .
.
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