IN BGP we need to manually advertised network/s.
Methods by which we can advertise Network/s in BGP -
>Using Network Command
In IGP like OSPF , EIGRP we have seen that once we use network command then all the interfaces falling in the range of network command will get active in IGP.
But in BGP that is not the case .
BGP refers the Routing table (not the interfaces) to install the route in its BGP table.
R1#sh int des
Interface Status Protocol Description
Fa0 admin down down
Lo0 up up
Se0 up up
Se1 admin down down
Se2 admin down down sh int des
Interface Status Protocol Description
Fa0 admin down down
Lo0 up up
Se0 up up
Se1 admin down down
Se2 admin down down
R1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0 unassigned YES NVRAM administratively down down
Loopback0 1.1.1.1 YES NVRAM up up
Serial0 12.1.1.1 YES NVRAM up up
Serial1 unassigned YES NVRAM administratively down down
Serial2 unassigned YES NVRAM administratively down down
R1#sh ip bgp sum
BGP router identifier 1.1.1.1, local AS number 100
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.2 4 200 3 3 1 0 0 00:00:34 0
R1#
R1#sh ip bgp
R1#
R2#sh int des
Interface Status Protocol Description
Fa0 admin down down
Se0 admin down down
Se1 up up
Se2 admin down down
R2#sh ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0 unassigned YES NVRAM administratively down down
Serial0 unassigned YES NVRAM administratively down down
Serial1 12.1.1.2 YES NVRAM up up
Serial2 unassigned YES NVRAM administratively down down
R2#
R2#sh ip bgp sum
BGP router identifier 2.2.2.2, local AS number 200
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.1 4 100 6 6 1 0 0 00:03:45 0
R2#
!!! Creating a loopback interface on R1
R1(config)#int loopback 0
R1(config-if)#ip address 1.1.1.1 255.255.255.255
R1(config-if)#^Z
R1#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
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, Serial0
R1#
R1(config)#router bgp 100
R1(config-router)#network 1.1.1.0 mask 255.255.255.0
R1#sh ip bgp <----------------------- Nothing in BGP table .
R2#sh ip bgp <---------------------------Nothing in BGP table
R2#sh ip bgp sum
BGP router identifier 2.2.2.2, local AS number 200
BGP table version is 3, main routing table version 3
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.1 4 100 25 23 3 0 0 00:20:43 0
R2#
No prefixes received from R1
Lets configure exact network
R1#config
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#no network 1.1.1.0 mask 255.255.255.0
R1(config-router)#network 1.1.1.1 mask 255.255.255.255
R1(config-router)#^Z
R1#sh ip bgp
BGP table version is 4, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
R1#
R2#sh ip bgp sum
BGP router identifier 2.2.2.2, local AS number 200
BGP table version is 4, main routing table version 4
1 network entries using 117 bytes of memory
1 path entries using 52 bytes of memory
2/1 BGP path/bestpath attribute entries using 248 bytes of memory
1 BGP AS-PATH entries using 24 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 441 total bytes of memory
BGP activity 2/1 prefixes, 2/1 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.1 4 100 33 30 4 0 0 00:27:13 1
R2#
R2#sh ip bgp
BGP table version is 4, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 12.1.1.1 0 0 100 i
R3#sh ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0 13.1.1.3 YES manual up up
Loopback3 3.3.3.3 YES manual up up
R1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0 13.1.1.1 YES manual up up
Loopback0 1.1.1.1 YES NVRAM up up
Serial0 12.1.1.1 YES NVRAM up up
R1(config)#ip route 3.3.3.3 255.255.255.255 13.1.1.3
R1(config)#^Z
R1#p
Dec 13 01:44:30.495: %SYS-5-CONFIG_I: Configured from console by console
R1#ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
R1#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
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
3.0.0.0/32 is subnetted, 1 subnets
S 3.3.3.3 [1/0] via 13.1.1.3
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, Serial0
13.0.0.0/24 is subnetted, 1 subnets
C 13.1.1.0 is directly connected, FastEthernet0
R1#
3.3.3.3/32 is not an interface of R1 but it a route in routing table of R1.
Let's us advertise the same in BGP and check whether its gets installed in BGP table -
R1#config
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#network 3.3.3.3 mask 255.255.255.255
R1(config-router)#^Z
R1#
R1#sh i
Dec 13 01:47:27.687: %SYS-5-CONFIG_I: Configured from console by console
R1#sh ip bgp
BGP table version is 5, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 3.3.3.3/32 13.1.1.3 0 32768 i
R1#
R2#sh ip bg
BGP table version is 5, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 12.1.1.1 0 0 100 i
*> 3.3.3.3/32 12.1.1.1 0 0 100 i
R2#
It's getting successfully installed in BGP TABLE.
==============================================================
•The routes from other Routing Protocols can be redistributed into BGP.
•Using redistribution command .
•These routers are represented by origin code – “?”
R1(config)#int loopback 100
R1(config-if)#ip add 100.100.100.1 255.255.255.0
R1(config)#router eigrp 10
R1(config-router)#network 100.100.100.0 255.255.255.0
R1(config-router)#^Z
R1#
Dec 13 02:02:35.235: %SYS-5-CONFIG_I: Configured from console by console
R1#config
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#red
R1(config-router)#redistribute ei
R1(config-router)#redistribute eigrp ?
<1-65535> Autonomous system number
R1(config-router)#redistribute eigrp 10
R1(config-router)#^Z
R1#
Dec 13 02:02:53.767: %SYS-5-CONFIG_I: Configured from console by console
R1#
R1#sh ip bgp
BGP table version is 6, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 3.3.3.3/32 13.1.1.3 0 32768 i
*> 100.100.100.0/24 0.0.0.0 0 32768 ?
R2#sh ip bgp
BGP table version is 6, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 12.1.1.1 0 0 100 i
*> 3.3.3.3/32 12.1.1.1 0 0 100 i
*> 100.100.100.0/24 12.1.1.1 0 0 100 ?
Thanks for Reading !!!!
Methods by which we can advertise Network/s in BGP -
>Using Network Command
>Redistribution
1) Using Network Command.
In IGP like OSPF , EIGRP we have seen that once we use network command then all the interfaces falling in the range of network command will get active in IGP.
But in BGP that is not the case .
BGP refers the Routing table (not the interfaces) to install the route in its BGP table.
 |
| Network Advertisement in BGP |
R1#sh int des
Interface Status Protocol Description
Fa0 admin down down
Lo0 up up
Se0 up up
Se1 admin down down
Se2 admin down down sh int des
Interface Status Protocol Description
Fa0 admin down down
Lo0 up up
Se0 up up
Se1 admin down down
Se2 admin down down
R1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0 unassigned YES NVRAM administratively down down
Loopback0 1.1.1.1 YES NVRAM up up
Serial0 12.1.1.1 YES NVRAM up up
Serial1 unassigned YES NVRAM administratively down down
Serial2 unassigned YES NVRAM administratively down down
R1#sh ip bgp sum
BGP router identifier 1.1.1.1, local AS number 100
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.2 4 200 3 3 1 0 0 00:00:34 0
R1#
R1#sh ip bgp
R1#
R2#sh int des
Interface Status Protocol Description
Fa0 admin down down
Se0 admin down down
Se1 up up
Se2 admin down down
R2#sh ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0 unassigned YES NVRAM administratively down down
Serial0 unassigned YES NVRAM administratively down down
Serial1 12.1.1.2 YES NVRAM up up
Serial2 unassigned YES NVRAM administratively down down
R2#
R2#sh ip bgp sum
BGP router identifier 2.2.2.2, local AS number 200
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.1 4 100 6 6 1 0 0 00:03:45 0
R2#
!!! Creating a loopback interface on R1
R1(config)#int loopback 0
R1(config-if)#ip address 1.1.1.1 255.255.255.255
R1(config-if)#^Z
R1#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
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, Serial0
R1#
R1(config)#router bgp 100
R1(config-router)#network 1.1.1.0 mask 255.255.255.0
R1#sh ip bgp <----------------------- Nothing in BGP table .
R2#sh ip bgp <---------------------------Nothing in BGP table
R2#sh ip bgp sum
BGP router identifier 2.2.2.2, local AS number 200
BGP table version is 3, main routing table version 3
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.1 4 100 25 23 3 0 0 00:20:43 0
R2#
No prefixes received from R1
Lets configure exact network
R1#config
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#no network 1.1.1.0 mask 255.255.255.0
R1(config-router)#network 1.1.1.1 mask 255.255.255.255
R1(config-router)#^Z
R1#sh ip bgp
BGP table version is 4, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
R1#
R2#sh ip bgp sum
BGP router identifier 2.2.2.2, local AS number 200
BGP table version is 4, main routing table version 4
1 network entries using 117 bytes of memory
1 path entries using 52 bytes of memory
2/1 BGP path/bestpath attribute entries using 248 bytes of memory
1 BGP AS-PATH entries using 24 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 441 total bytes of memory
BGP activity 2/1 prefixes, 2/1 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.1 4 100 33 30 4 0 0 00:27:13 1
R2#
R2#sh ip bgp
BGP table version is 4, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 12.1.1.1 0 0 100 i
Lets prove -" BGP refers the Routing table (not the interfaces) to install the route in its BGP table."
 |
| UNDERSTANDING NETWORK ADVERTISEMENT IN BGP |
R3#sh ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0 13.1.1.3 YES manual up up
Loopback3 3.3.3.3 YES manual up up
R1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0 13.1.1.1 YES manual up up
Loopback0 1.1.1.1 YES NVRAM up up
Serial0 12.1.1.1 YES NVRAM up up
R1(config)#ip route 3.3.3.3 255.255.255.255 13.1.1.3
R1(config)#^Z
R1#p
Dec 13 01:44:30.495: %SYS-5-CONFIG_I: Configured from console by console
R1#ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
R1#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
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
3.0.0.0/32 is subnetted, 1 subnets
S 3.3.3.3 [1/0] via 13.1.1.3
12.0.0.0/24 is subnetted, 1 subnets
C 12.1.1.0 is directly connected, Serial0
13.0.0.0/24 is subnetted, 1 subnets
C 13.1.1.0 is directly connected, FastEthernet0
R1#
3.3.3.3/32 is not an interface of R1 but it a route in routing table of R1.
Let's us advertise the same in BGP and check whether its gets installed in BGP table -
R1#config
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#network 3.3.3.3 mask 255.255.255.255
R1(config-router)#^Z
R1#
R1#sh i
Dec 13 01:47:27.687: %SYS-5-CONFIG_I: Configured from console by console
R1#sh ip bgp
BGP table version is 5, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 3.3.3.3/32 13.1.1.3 0 32768 i
R1#
R2#sh ip bg
BGP table version is 5, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 12.1.1.1 0 0 100 i
*> 3.3.3.3/32 12.1.1.1 0 0 100 i
R2#
It's getting successfully installed in BGP TABLE.
==============================================================
2) Redistribution
•The routes from other Routing Protocols can be redistributed into BGP.
•Using redistribution command .
•These routers are represented by origin code – “?”
R1(config)#int loopback 100
R1(config-if)#ip add 100.100.100.1 255.255.255.0
R1(config)#router eigrp 10
R1(config-router)#network 100.100.100.0 255.255.255.0
R1(config-router)#^Z
R1#
Dec 13 02:02:35.235: %SYS-5-CONFIG_I: Configured from console by console
R1#config
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#red
R1(config-router)#redistribute ei
R1(config-router)#redistribute eigrp ?
<1-65535> Autonomous system number
R1(config-router)#redistribute eigrp 10
R1(config-router)#^Z
R1#
Dec 13 02:02:53.767: %SYS-5-CONFIG_I: Configured from console by console
R1#
R1#sh ip bgp
BGP table version is 6, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 3.3.3.3/32 13.1.1.3 0 32768 i
*> 100.100.100.0/24 0.0.0.0 0 32768 ?
R2#sh ip bgp
BGP table version is 6, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 12.1.1.1 0 0 100 i
*> 3.3.3.3/32 12.1.1.1 0 0 100 i
*> 100.100.100.0/24 12.1.1.1 0 0 100 ?
Thanks for Reading !!!!
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