Cisco L2TPv3 の冗長化
L2TPv3 の Peer に Loopback インターフェースを指定し、当該ネットワークを OSPF 等のダイナミックルーティングで解決させる事で冗長化が可能です。切替時間は、ダイナミックルーティングの収束時間に依存します。
検証環境
設定例
メイン及び、バックアップ回線は、マルチキャストを透過しない WAN（地域 IP 網等）を想定します。
L2TPv3 用の Peer ネットワーク（Loopback）を、GRE over OSPF でメイン回線へアドバタイズし、バックアップ回線向けの Floating Static を定義します。
R1: csr1000v-packages-adventerprisek9.03.09.01.S.153-2.S1
hostname R1 ! pseudowire-class l2tpv3 encapsulation l2tpv3 ip local interface Loopback1 ! interface Loopback1 ip address 1.1.1.1 255.255.255.0 ip ospf network point-to-point ! interface Tunnel1 ip address 172.16.11.1 255.255.255.252 tunnel source GigabitEthernet2 tunnel destination 172.16.1.2 ! interface Tunnel2 ip address 172.16.12.1 255.255.255.252 tunnel source GigabitEthernet3 tunnel destination 172.16.2.2 ! interface GigabitEthernet1 no ip address negotiation auto no keepalive xconnect 2.2.2.2 1 encapsulation l2tpv3 pw-class l2tpv3 ! interface GigabitEthernet2 ip address 172.16.1.1 255.255.255.0 shutdown negotiation auto ! interface GigabitEthernet3 ip address 172.16.2.1 255.255.255.0 negotiation auto ! router ospf 1 network 1.1.1.0 0.0.0.255 area 0 network 172.16.11.0 0.0.0.3 area 0 ! ip route 2.2.2.0 255.255.255.0 Tunnel2 200 ! end
R2: csr1000v-packages-adventerprisek9.03.09.01.S.153-2.S1
hostname R2 ! pseudowire-class l2tpv3 encapsulation l2tpv3 ip local interface Loopback1 interface Loopback1 ip address 2.2.2.2 255.255.255.0 ip ospf network point-to-point ! interface Tunnel1 ip address 172.16.11.2 255.255.255.252 tunnel source GigabitEthernet2 tunnel destination 172.16.1.1 ! interface Tunnel2 ip address 172.16.12.2 255.255.255.252 tunnel source GigabitEthernet3 tunnel destination 172.16.2.1 ! interface GigabitEthernet1 no ip address negotiation auto no keepalive xconnect 1.1.1.1 1 encapsulation l2tpv3 pw-class l2tpv3 ! interface GigabitEthernet2 ip address 172.16.1.2 255.255.255.0 negotiation auto ! interface GigabitEthernet3 ip address 172.16.2.2 255.255.255.0 negotiation auto ! router ospf 1 network 2.2.2.0 0.0.0.255 area 0 network 172.16.11.0 0.0.0.3 area 0 ! ip route 1.1.1.0 255.255.255.0 Tunnel2 200 ! end
R3: csr1000v-packages-universalk9.03.10.00.S.153-3.S
hostname R3 ! interface GigabitEthernet1 no ip address negotiation auto service instance 1 ethernet encapsulation untagged bridge-domain 1 ! interface GigabitEthernet2 no ip address negotiation auto service instance 1 ethernet encapsulation untagged bridge-domain 1 ! end
確認例
L2TPv3 を Loopback インターフェースで確立しています。
R1#show l2tp tunnel transport L2TP Tunnel Information Total tunnels 1 sessions 1 LocTunID Type Prot Local Address Port Remote Address Port 3886356642 IP 115 1.1.1.1 0 2.2.2.2 0
正常時、対向の Loopback は OSPF で学習しています。
R1#sh ip route 2.2.2.2
Routing entry for 2.2.2.0/24
Known via "ospf 1", distance 110, metric 1001, type intra area
Last update from 172.16.11.2 on Tunnel1, 01:20:40 ago
Routing Descriptor Blocks:
* 172.16.11.2, from 2.2.2.2, 01:20:40 ago, via Tunnel1
Route metric is 1001, traffic share count is 1R2-R3 間で障害発生時は、Floating Static により、Backup 経路を使用します。
R1#show ip route 2.2.2.2
Routing entry for 2.2.2.0/24
Known via "static", distance 200, metric 0 (connected)
Routing Descriptor Blocks:
* directly connected, via Tunnel2
Route metric is 0, traffic share count is 1L2TPv3 は新しい経路で再確立します。
R1#show l2tp session all
L2TP Session Information Total tunnels 1 sessions 1
Session id 2380820166 is up, logical session id 32777, tunnel id 3886356642
Remote session id is 375499793, remote tunnel id 303422462
Locally initiated session
Unique ID is 0
Session Layer 2 circuit, type is Ethernet, name is GigabitEthernet1
Session vcid is 1
Circuit state is UP
Local circuit state is UP
Remote circuit state is UP
Call serial number is 2047900001
Remote tunnel name is R2
Internet address is 2.2.2.2
Local tunnel name is R1
Internet address is 1.1.1.1
IP protocol 115
Session is L2TP signaled
Session state is established, time since change 01:28:06
0 Packets sent, 0 received
0 Bytes sent, 0 received
Last clearing of counters never
Counters, ignoring last clear:
0 Packets sent, 0 received
0 Bytes sent, 0 received
Receive packets dropped:
out-of-order: 0
other: 0
total: 0
Send packets dropped:
exceeded session MTU: 0
other: 0
total: 0
DF bit off, ToS reflect disabled, ToS value 0, TTL value 255
Sending UDP checksums are disabled
Received UDP checksums are verified
No session cookie information available
FS cached header information:
encap size = 24 bytes
45000014 00000000 ff73b571 01010101
02020202 1661ac11
Sequencing is off
Conditional debugging is disabled
SSM switch id is 4096, SSM segment id is 12300以上
