This is part of a series of posts – The Lisp Papers.
In the previous post on LISP, we looked at the control plane. This post will look at how we monitor the connectivity provided.
To see which ETRs are registered with the MS, do the following:
MSMR#sh lisp site detail LISP Site Registration Information Site name: CustomerA Allowed configured locators: any Allowed EID-prefixes: EID-prefix: 10.1.1.0/24 First registered: 00:00:59 Routing table tag: 0x0 Origin: Configuration, accepting more specifics Registration errors: Authentication failures: 0 Allowed locators mismatch: 0 ETR 10.1.3.2, last registered 00:00:59, no proxy-reply TTL 1d00h Locator Local State Pri/Wgt 10.255.255.1 yes up 2/50 Site name: CustomerB Allowed configured locators: any Allowed EID-prefixes: EID-prefix: 10.1.2.0/24 First registered: 00:00:55 Routing table tag: 0x0 Origin: Configuration, accepting more specifics Registration errors: Authentication failures: 0 Allowed locators mismatch: 0 ETR 10.1.3.6, last registered 00:00:55, no proxy-reply TTL 1d00h Locator Local State Pri/Wgt 10.255.255.2 yes up 2/50 MSMR#
At this point, I would like to ask you to cast your mind back to your very first networking course. Perhaps (like me) this was the MCSE Networking Essentials or maybe the CCNA. Regardless, I would guess that it discussed the ping command. Using it every day, I had forgotten that ping is actually an acronym. Do you know what it stands for?
Packet INternet Groper
Well, the good designers and architects of LISP had not forgotten. So when they developed a ping-like application for querying the LISP Mapping Database it became, predictably, the LISP Internet Groper, or LIG.
The use of LIG is as follows:
xTR2#lig ? Hostname or A.B.C.D IPv4 Destination Endpoint ID (EID) self Test if local EID-prefix is registered in the mapping database xTR2#lig 10.1.1.0 Mapping information for EID 10.1.1.0 from 10.1.3.2 with RTT 664 msecs 10.1.1.0/24, uptime: 00:00:05, expires: 23:59:56, via map-reply, complete Locator Uptime State Pri/Wgt 10.255.255.1 00:00:05 up 2/50
Where 10.1.1.0 is the remote EID and 10.1.3.2 (and 10.255.255.1, which is the loopback) is the remote ETR.
The LISP forwarding table on an ITR can be examined as follows: xTR2#sh ip lisp forwarding eid remote Prefix Fwd action Locator status bits 0.0.0.0/0 signal 0x00000000 packets/bytes 0/0 10.1.1.0/24 encap 0x00000001 packets/bytes 5/430
and the CEF table looks like the following:
xTR2#sh ip cef 10.1.1.0 detail 10.1.1.0/24, epoch 0, flags subtree context, check lisp eligibility SC owned: LISP remote EID - locator status bits 0x00000001 LISP remote EID: 5 packets 430 bytes fwd action encap 2 IPL sources [active source] Dependent covered prefix type inherit cover 0.0.0.0/0 LISP source path list nexthop 10.255.255.1 LISP0 recursive via 0.0.0.0/0 attached to Null0