Beranda > @GNS3 Lab, Routing TCP/IP Volume 1 > Troubleshoot Routing Statik: Melacak Jejak IPv6 Route yang Gagal

Troubleshoot Routing Statik: Melacak Jejak IPv6 Route yang Gagal

Sebuah link dibuat antara Honeypot dan Honeytree agar network memiliki router alternatif sebagai backup jika route primer mengalami kegagalan. Gambar dibawah adalah topologi network yang baru. Aplikasi IPv6 yang menggunakan network kurang sensitif terhadap delay, tetapi aplikasi tersebut memanfaatkan bandwidth dengan penuh, jadi admin memutuskan untuk menggunakan link baru sebagai load sharing. Routing statik dikonfigurasi agar memanfaatkan link baru.

topologi_ipv6fail

Sebuah contoh berikut menunjukkan entri-entri route yang ditambahkan pada Honeypot untuk membuat route kedua (alternatif) dari setiap route yang ada. Hal yang sama juga dikonfigurasikan untuk Honeytree dan Honeybee.

Honeypot#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Honeypot(config)#ipv6 unic
Honeypot(config)#ipv6 unicast-routing
Honeypot(config)#ipv6 route FEC0::/62 FEC0::3:CE03:CFF:FED4:10
Honeypot(config)#ipv6 route FEC0::/62 FEC0::2:CE04:CFF:FED4:10
Honeypot(config)#ipv6 route FEC0:0:0:8::/62 FEC0::3:CE03:CFF:FED4:10
Honeypot(config)#ipv6 route FEC0:0:0:8::/62 FEC0::2:CE04:CFF:FED4:10
Honeypot(config)#^Z
Honeypot#
Honeytree#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Honeytree(config)#ipv6 unicast-routing
Honeytree(config)#ipv6 route FEC0:0:03::/64 FEC0::1:CE03:CFF:FED4:10
Honeytree(config)#ipv6 route FEC0:0:03::/64 FEC0::2:CE05:CFF:FED4:10
Honeytree(config)#NO ipv6 route FEC0:0:03::/64 FEC0::1:CE03:CFF:FED4:10
Honeytree(config)#no ipv6 route FEC0:0:03::/64 FEC0::2:CE05:CFF:FED4:10
Honeytree(config)#do sh run | incl route
Honeytree(config)#ipv6 route fec0:0:0:3::/64 FEC0::1:CE03:CFF:FED4:10
Honeytree(config)#ipv6 route fec0:0:0:3::/64 FEC0::2:CE05:CFF:FED4:10
Honeytree(config)#ipv6 route fec0:0:0:5::/64 FEC0::2:CE05:CFF:FED4:10
Honeytree(config)#ipv6 route fec0:0:0:5::/64 FEC0::1:CE03:CFF:FED4:10
Honeytree(config)#ipv6 route fec0:0:0:9::/64 FEC0::1:CE03:CFF:FED4:10
Honeytree(config)#no ipv6 route fec0:0:0:9::/64 FEC0::1:CE03:CFF:FED4:10
Honeytree(config)#ipv6 route fec0:0:0:8::/64 FEC0::1:CE03:CFF:FED4:10
Honeytree(config)#ipv6 route fec0:0:0:8::/64 FEC0::2:CE05:CFF:FED4:10
Honeytree(config)#^Z
Honeytree#
Honeybee#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Honeybee(config)#ipv6 unicast-rou
Honeybee(config)#ipV route FEC0:0:0:2::/64 FEC0::3:CE05:CFF:FED4:10
Honeybee(config)#ipv route FEC0:0:0:2::/64 FEC0::1:CE04:CFF:FED4:10
Honeybee(config)#ipv route fec0:0:0:5::/64 FEC0::1:CE04:CFF:FED4:10
Honeybee(config)#ipv route fec0:0:0:5::/64 FEC0::3:CE05:CFF:FED4:10
Honeybee(config)#ipv route fec0:0:0:b::/64 FEC0::3:CE05:CFF:FED4:10
Honeybee(config)#ipv route fec0:0:0:b::/64 FEC0::1:CE04:CFF:FED4:10
Honeybee(config)#^Z
Honeybee#

Router IPv6 rentan akan kegagalan. Kadang-kadang ping bekerja, dan kadang tidak. Dari tabel routing menunjukkan bahwa semua routing statik telah dimasukkan, tetapi ping dari Honeypot ke ethernet interface  Honeybee kadang-kadang berjalan dengan baik, dan kadang tidak.

Honeypot#ping FEC0::8:CE03:CFF:FED4:10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FEC0::8:CE03:CFF:FED4:10, timeout is 2 seconds:
H!!!H
Success rate is 60 percent (3/5), round-trip min/avg/max = 24/48/88 ms
Honeypot#

Dengan mendebug paket ICMP IPv6 pada Honeypot, dapat diketahui bahwa paket reply diterima dengan sempurna, tetapi kadang beberapa pesan ICMP berupa destination unreachable datang dari Honeytree.

Honeypot# debug ipv6 icmp
*Mar  1 01:14:46.963: ICMPv6: Sending echo request to FEC0::8:CE03:CFF:FED4:10
*Mar  1 01:14:47.047: ICMPv6: Received ICMPv6 packet from FEC0::2:CE04:CFF:FED4:10, type 1
*Mar  1 01:14:47.047: ICMPv6: Received ICMP unreachable code 3 from FEC0::2:CE04:CFF:FED4:10
*Mar  1 01:14:47.051: ICMPv6: Sending echo request to FEC0::8:CE03:CFF:FED4:10
*Mar  1 01:14:47.143: ICMPv6: Received ICMPv6 packet from FEC0::8:CE03:CFF:FED4:10, type 129
*Mar  1 01:14:47.143: ICMPv6: Received echo reply from FEC0::8:CE03:CFF:FED4:10
*Mar  1 01:14:47.147: ICMPv6: Sending echo request to FEC0::8:CE03:CFF:FED4:10
*Mar  1 01:14:47.223: ICMPv6: Received ICMPv6 packet from FEC0::8:CE03:CFF:FED4:10, type 129
*Mar  1 01:14:47.223: ICMPv6: Received echo reply from FEC0::8:CE03:CFF:FED4:10
*Mar  1 01:14:47.227: ICMPv6: Sending echo request to FEC0::8:CE03:CFF:FED4:10
*Mar  1 01:14:47.243: ICMPv6: Received ICMPv6 packet from FEC0::8:CE03:CFF:FED4:10, type 129
*Mar  1 01:14:47.243: ICMPv6: Received echo reply from FEC0::8:CE03:CFF:FED4:10
*Mar  1 01:14:47.247: ICMPv6: Sending echo request to FEC0::8:CE03:CFF:FED4:10
*Mar  1 01:14:47.271: ICMPv6: Received ICMPv6 packet from FEC0::2:CE04:CFF:FED4:10, type 1
*Mar  1 01:14:47.271: ICMPv6: Received ICMP unreachable code 3 from FEC0::2:CE04:CFF:FED4:10

Debugging ICMPv6 pada Honeytree menunjukkan bahwa paket IPv6 datang dari S0/0 dan juga S0/1.

Honeytree#
*Mar  1 01:22:03.799: IPV6: source FEC0::8:CE03:CFF:FED4:10 (Serial0/0)
*Mar  1 01:22:03.799:       dest FEC0::2:CE05:CFF:FED4:10 (Serial0/1)
*Mar  1 01:22:03.799:       traffic class 0, flow 0x0, len 100+4, prot 58, hops 63, forwarding
*Mar  1 01:22:03.807: IPV6: source FEC0::2:CE05:CFF:FED4:10 (Serial0/1)
*Mar  1 01:22:03.807:       dest FEC0::8:CE03:CFF:FED4:10 (Serial0/1)
*Mar  1 01:22:03.807:       traffic class 0, flow 0x0, len 100+4, prot 58, hops 64, destination is not connected
*Mar  1 01:22:03.811: IPv6: SAS picked source FEC0::2:CE04:CFF:FED4:10 for FEC0::2:CE05:CFF:FED4:10 (Serial0/1)
*Mar  1 01:22:03.811: ICMPv6: Sending ICMP unreachable code 3 to FEC0::2:CE05:CFF:FED4:10 about FEC0::8:CE03:CFF:FED
*Mar  1 01:22:03.811: IPV6: source FEC0::2:CE04:CFF:FED4:10 (local)
*Mar  1 01:22:03.811:       dest FEC0::2:CE05:CFF:FED4:10 (Serial0/1)
*Mar  1 01:22:03.815:       traffic class 0, flow 0x0, len 148+0, prot 58, hops 64, originating

Paket-paket dengan address source FEC0::2:CE05:CFF:FED4:10 tiba pada interface s0/1  Honeytree. Exit interface untuk destination FEC0::8:CE03:CFF:FED4:10 dapat berupa s0/0 atau s0/1. Honeytree akan melakukan load-sharing pada paket, menggunakan paket forwarding secara seimbang antara s0/0 dan s0/1. Ketika outgoing interface-nya adalah s0/0 dan data diterima dari interface s0/1, maka paket akan di forward. Ketika data di forward ke interface s0/1, yang merupakan interface dimana paket diterima, maka ping pada router akan mengalami kegagalan dan router mengirimkan pesan ICMP error.

Sebuah paket yang dikirimkan keluar pada interface yang sama dimana paket datang mengindikasikan adanya routing loop. Karena router-router melakukan proses switching dan load sharing tiap paket, maka router akan menggunakan setiap entri routenya secara bergantian. Karena itu, Beberapa paket akan dikirim keluar pada interface yang sama dimana paket diterima.

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