Configurar y verificar la conectividad de single-homed branch usando IPv4 eBGP (CCNA 200-125)
Diagrama
Objetivos
- Configuración de eBGP
- Verificar conectividad
- Revisión de comandos para verificar y solucionar problemas eBGP
Conceptos
- BGP ( Border Gateway Protocol), se define en el RFC 1771 , y es un protocolo que se utilizan en los nodos de Internet el cual intercambian información de encaminamiento o ruteo entre sistemas autónomos (AS).
- Un sistema autónomo es un conjunto de routers bajo una sola administración técnica
- BGP tiene como misión encontrar el camino más eficiente entre los nodos para propiciar una correcta circulación de la información en Internet.
- Dos routers cualquiera que formen una conexión TCP para intercambiar información de enrutamiento BGP son "pares" o "vecinos“
- Cuando BGP se ejecuta entre routers que pertenecen a dos AS diferentes, recibe el nombre de BGP externo (eBGP). Cuando BGP se ejecuta entre routers del mismo AS, recibe el nombre de iBGP.
Configuración – Tabla Direccionamiento IP
Configuración Router1
- Router1(config)# interface Loopback0
- Router1(config-if)# ip address 1.1.1.1 255.255.255.0
- Router1(config-if)# interface GigabitEthernet0/0
- Router1(config-if)# ip address 1.1.2.1 255.255.255.252
- Router1(config)# router bgp 100
- Router1(config)# neighbor 1.1.2.2 remote-as 200
- Router1(config)# network 1.1.1.0 mask 255.255.255.0
- Router1(config)# exit
- Router1# copy run star
Configuración Router2
- Router2(config)# interface Loopback0
- Router2(config-if)# ip address 1.1.3.3 255.255.255.0
- Router2(config-if)# interface GigabitEthernet0/0
- Router2(config-if)# ip address 1.1.2.2 255.255.255.252
- Router2(config)# router bgp 200
- Router2(config)# neighbor 1.1.2.1 remote-as 200
- Router2(config)# network 1.1.3.0 mask 255.255.255.0
- Router2(config)# exit
- Router2# copy run star
Verificación de conectividad
- Ping desde Router1 a Router2 (1.1.3.3)
- Ping desde Router2 a Router1 (1.1.1.1)
Resultados, con respuesta satisfactoria:
Router1#ping 1.1.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/1 ms
Router2#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/1 ms
Revisión de comandos para verificar y solucionar problemas de eBGP
- show ip bgp
- show ip bgp neighbors
- show ip bgp summary
- show ip route bgp
Resultados de verificación:
Router1#sh ip bgp
BGP table version is 3, 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
*> 1.1.1.0/24 0.0.0.0 0 0 32768 i
*> 1.1.3.0/24 1.1.2.2 0 0 0 200 i
Router1#sh ip bgp neighbors
BGP neighbor is 1.1.2.2, remote AS 200, external link
BGP version 4, remote router ID 1.1.3.3
BGP state = Established, up for 00:10:39
Last read 00:10:39, last write 00:10:39, hold time is 180, keepalive interval is 60 seconds
Neighbor capabilities:
Route refresh: advertised and received(new)
Address family IPv4 Unicast: advertised and received
Message statistics:
InQ depth is 0
OutQ depth is 0
Sent Rcvd
Opens: 1 1
Notifications: 0 0
Updates: 1 1
Keepalives: 11 11
Route Refresh: 0 0
Total: 13 13
Default minimum time between advertisements runs is 30 seconds
For address family: IPv4 Unicast
BGP table version 3, neighbor version 6/0
Output queue size : 0
Index 1, Offset 0, Mask 0x2
1 update-group member
Sent Rcvd
Prefix activity: ---- ----
Prefixes Current: 1 1 (Consumes 46 bytes)
Prefixes total: 1 1
Implicit Withdraw: 0 0
Explicit Withdraw: 0 0
Used as bestpath: n/a 1
Used as multipath: n/a 0
Outbound Inbound
Local Policy Denied Prefixes: -------- -------
Total: 0 0
Number of NLRIs in the update sent: max 3, min 1
Address tracking is enabled, the RIB does have a route to 1.1.2.2
Connections established 1; dropped 0
Last reset never
Transport(tcp) path-mtu-discovery is enabled
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Connection is ECN Disabled, Minimum incoming TTL 0, Outgoing TTL 1
Local host: 1.1.2.1, Local port: 179
Foreign host: 1.1.2.2, Foreign port: 1025
Connection tableid (VRF): 0
Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)
Event Timers (current time is 0xC69F4):
Timer Starts Wakeups Next
Retrans 0 0 0x0
TimeWait 0 0 0x0
AckHold 12 0 0x0
SendWnd 0 0 0x0
KeepAlive 11 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0
Linger 0 0 0x0
ProcessQ 0 0 0x0
iss: 2057115318 snduna: 2057115748 sndnxt: 2057115748 sndwnd: 15955
irs: 3480424370 rcvnxt: 3480424751 rcvwnd: 16004 delrcvwnd: 380
SRTT: 259 ms, RTTO: 579 ms, RTV: 320 ms, KRTT: 0 ms
minRTT: 16 ms, maxRTT: 300 ms, ACK hold: 200 ms
Status Flags: passive open, gen tcbs
Option Flags: nagle, path mtu capable
IP Precedence value : 6
Datagrams (max data segment is 1460 bytes):
Rcvd: 13 (out of order: 0), with data: 0, total data bytes: 0
Sent: 12 (retransmit: 0, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data: 1, total data bytes: 24
Packets received in fast path: 0, fast processed: 0, slow path: 0
fast lock acquisition failures: 0, slow path: 0
Router1#sh ip bgp summary
BGP router identifier 1.1.1.1, local AS number 100
BGP table version is 3, main routing table version 6
2 network entries using 264 bytes of memory
2 path entries using 104 bytes of memory
1/1 BGP path/bestpath attribute entries using 184 bytes of memory
2 BGP AS-PATH entries using 48 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
Bitfield cache entries: current 1 (at peak 1) using 32 bytes of memory
BGP using 632 total bytes of memory
BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
1.1.2.2 4 200 15 14 3 0 0 00:12:05 4
Router1#sh ip route bgp
B 1.1.3.0/24 [20/0] via 1.1.2.2, 00:14:49
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