#100DaysOfLabbing - Day 1 & 2

It's actually day 3 as I write this but I wanted to put down some documentation I've been keeping in a text document.

I learned a few things doing the configs on Day 1 and Day 2. Some of them simpler than others but worth noting.

This is the DMVPN Cisco Validated Design Guide I mentioned:

https://supportforums.cisco.com/legacyfs/online/legacy/3/9/5/26593-DMVPNbk.pdf

Day 1

Day 2

Basic DMVPN

#1 Lesson Learned

!Hub int tun 0 ip add 10.123.234.1 255.255.255.0 tunnel source Gi0/0 tunnel mode gre multipoint no shut !Spoke int tun 0 ip add 10.123.234.2 255.255.255.0 tunnel source Gi0/0 tunnel destination 10.123.234.1 no shut ! Broke R2#sho int tun 0 Tunnel0 is up, line protocol is down   Hardware is Tunnel   Internet address is 10.123.234.2/24   MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec,      reliability 255/255, txload 1/255, rxload 1/255   Encapsulation TUNNEL, loopback not set   Keepalive not set   Tunnel linestate evaluation down - no output interface   Tunnel source 172.17.100.2 (GigabitEthernet0/0), destination 10.123.234.1    Tunnel Subblocks:       src-track:          Tunnel0 source tracking subblock associated with GigabitEthernet0/0           Set of tunnels with source GigabitEthernet0/0, 1 member (includes iterators), on interface <OK>   Tunnel protocol/transport GRE/IP     Key disabled, sequencing disabled     Checksumming of packets disabled   Tunnel TTL 255, Fast tunneling enabled   Tunnel transport MTU 1476 bytes   Tunnel transmit bandwidth 8000 (kbps)   Tunnel receive bandwidth 8000 (kbps)   Last input never, output never, output hang never Lesson Learned: I made the error of incorrectly defining the tunnel destination. I defined it as the remote tunnel interface when actually I needed to use the public NBMA address. Fixed: R2#sho int tun 0 Tunnel0 is up, line protocol is up   Hardware is Tunnel   Internet address is 10.123.234.2/24   MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec,      reliability 255/255, txload 1/255, rxload 1/255   Encapsulation TUNNEL, loopback not set   Keepalive not set   Tunnel linestate evaluation up   Tunnel source 172.17.100.2 (GigabitEthernet0/0), destination 172.17.100.1    Tunnel Subblocks:       src-track:          Tunnel0 source tracking subblock associated with GigabitEthernet0/0           Set of tunnels with source GigabitEthernet0/0, 1 member (includes iterators), on interface <OK>   Tunnel protocol/transport GRE/IP     Key disabled, sequencing disabled     Checksumming of packets disabled   Tunnel TTL 255, Fast tunneling enabled   Tunnel transport MTU 1476 bytes   Tunnel transmit bandwidth 8000 (kbps)   Tunnel receive bandwidth 8000 (kbps)   Last input never, output never, output hang never Explanation: The tunnel interface linestate stays down until it has a valid exit interface and route to the remote tunnel destination.

#2 Lesson Learned - Tunnel Keepalives

In the output below you can see "Keepalive not set". Tunnel keepalives are not set by default. You can configure keepalives under the tunnel interface. You can do this be specifying just the keyword "keepalive" and press enter. This will give you the default value of keepalives sent every 10 seconds and will retry 3 times before considering the tunnel down. Conversely you can specify the keepalive values( example 5 seconds) the retry values can also be set but if they are excluded will default to 3 retries. R4#sho int tun 0 Tunnel0 is up, line protocol is up   Hardware is Tunnel   Internet address is 10.123.234.4/24   MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec,      reliability 255/255, txload 1/255, rxload 1/255   Encapsulation TUNNEL, loopback not set   Keepalive not set [ ... output omitted ... ] Keepalive with default values R3(config-if)#keepalive ?   <0-32767>  Keepalive period (default 10 seconds)   <cr> R3(config-if)#keepalive R3(config-if)# R3(config-if)#do sho int tun 0 Tunnel0 is up, line protocol is up   Hardware is Tunnel   Internet address is 10.123.234.3/24   MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec,      reliability 255/255, txload 1/255, rxload 1/255   Encapsulation TUNNEL, loopback not set   Keepalive set (10 sec), retries 3 [ ... output omitted ... ] Keepalive with defined values R4(config)#int tun 0 R4(config-if)#keepalive 5 R4(config-if)#end R4# R4#sho int tun 0 Tunnel0 is up, line protocol is up Hardware is Tunnel Internet address is 10.123.234.4/24 MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation TUNNEL, loopback not set Keepalive set (5 sec), retries 3 [ ... output omitted ... ]