Router Configuration¶
Example network and sample configuration¶
Assume that three routers in the same network, but at three different sites
(memphis.edu, arizona.edu, and colostate.edu), are connected to each other to
construct the following topology:
+-------------------------------------+
| /ndn/edu/memphis/%C1.Router/router1 |
+-------------------------------------+
/ 11 12\
/ \
route-cost = 25 / \ route-cost = 30
/ \
17 / \ 13
+-----------------------------------+ 7 10 +-------------------------------------+
|/ndn/edu/arizona/%C1.Router/router3|-------------------|/ndn/edu/colostate/%C1.Router/router2|
+-----------------------------------+ route-cost = 28 +-------------------------------------+
Figure: Network Topology
The number represents the connecting face id. For example,
/ndn/edu/memphis/%C1.Router/router1 is connected to
/ndn/edu/arizona/%C1.Router/router3 via face 11 and the route cost is 25. To reach
/ndn/edu/colostate/%C1.Router/router2 via face 12, the route cost is 30.
We will walk through setting up the faces and creating the configuration file for
/ndn/edu/memphis/%C1.Router/router1.
It is recommended to configure security as described at Security Configuration, before starting router configuration.
Step 1. Ensuring nfd is running¶
Type the following in the terminal:
nfd-status
If you see error while connecting to the forwarder (No such file or directory),
nfd is not running. Follow the instructions in Getting started with NFD to run nfd.
Since v0.4.0, NLSR no longer creates Faces for the neighbors that are
specified in nlsr.conf. Instead, it relies on the pre-existence of
the Faces in NFD. NLSR will obtain this information from NFD, and
configure its neighbors using this information.
To create faces it is now necessary to use the nfdc command. See man nfdc for
its documentation (online version).
Step 2. Determining FaceUri¶
Assume that /ndn/edu/arizona/%C1.Router/router3 has hostname router3.arizona.edu and
/ndn/edu/colostate/%C1.Router/router2 has IP address 79.123.10.145.
/ndn/edu/memphis/%C1.Router/router1 will consider FaceUri
udp4://router3.arizona.edu for router /ndn/edu/arizona/%C1.Router/router3 and
FaceUri udp4://79.123.10.145 for router /ndn/edu/colostate/%C1.Router/router2.
Step 3: Creating configuration file¶
Now, assume that /ndn/memphis.edu/router1 wants to advertise three name prefixes
(/ndn/memphis/sports/basketball/grizzlies, /ndn/memphis/entertainment/blues,
/ndn/news/memphis/politics/lutherking). The configuration file with the necessary
configuration commands follows:
; nlsr.conf starts here
; the general section contains all the general settings for router
general
{
; mandatory configuration command section network, site and router
network /ndn/ ; name of the network the router belongs to in ndn URI format
site /edu/memphis/ ; name of the site the router belongs to in ndn URI format
router /%C1.Router/router1 ; name of the network the router belongs to in ndn URI format
; lsa-refresh-time is the time in seconds, after which router will refresh its LSAs
lsa-refresh-time 1800 ; default value 1800. Valid values 240-7200
; InterestLifetime (in seconds) for LSA fetching
lsa-interest-lifetime 4 ; default value 4. Valid values 1-60
state-dir /var/lib/nlsr/ ; state directory to store all dynamic changes to NLSR
}
; the neighbors section contains the configuration for router's neighbors and hello's behavior
neighbors
{
; in case hello interest timed out, router will try 'hello-retries' times at 'hello-time-out'
; seconds interval before giving up for any neighbors (deciding link is down)
hello-retries 3 ; interest retries number in integer. Default value 3
; valid values 1-10
hello-timeout 1 ; interest time out value in integer. Default value 1
; Valid values 1-15
hello-interval 60 ; interest sending interval in seconds. Default value 60
; valid values 30-90
; adj-lsa-build-interval is the time to wait in seconds after an Adjacency LSA
; build is scheduled before actually building the Adjacency LSA
adj-lsa-build-interval 5 ; default value 5. Valid values 0-5. It is recommended that
; adj-lsa-build-interval have a lower value than
; routing-calc-interval
; first-hello-interval is the time to wait in seconds before sending the first Hello Interest
first-hello-interval 10 ; Default value 10. Valid values 0-10
; neighbor command is used to configure router's neighbor. Each neighbor will need
; one block of neighbor command
neighbor
{
name /ndn/edu/arizona/%C1.Router/router3 ; name prefix of the neighbor router consists
; of network, site-name and router-name
face-uri udp4://router3.arizona.edu ; face uri of the face connected to the neighbor
link-cost 25 ; cost of the connecting link to neighbor
}
neighbor
{
name /ndn/edu/colostate/%C1.Router/router2 ; name prefix of the neighbor router consists
; of network, site-name and router-name
face-uri udp4://79.123.10.145 ; face uri of the face connected to the neighbor
link-cost 30 ; cost of the connecting link to neighbor
}
}
; the hyperbolic section contains the configuration settings of enabling
a router to calculate ; routing table using `hyperbolic routing table
calculation`_ method
hyperbolic
{
; commands in this section follows a strict order
; the switch is used to set hyperbolic routing calculation in NLSR
state off ; default value 'off', set value 'on' to enable hyperbolic routing table
; calculation which turns link state routing 'off'. set value to 'dry-run'
; to test hyperbolic routing and compare with link state routing.
radius 123.456 ; radius of the router in hyperbolic coordinate system
angle 1.45 ; angle of the router in hyperbolic coordinate system
}
; the fib section is used to configure fib entry's type to ndn FIB updated by NLSR
fib
{
; the max-faces-per-prefix is used to limit the number of faces for each name prefixes
; by NLSR in ndn FIB
max-faces-per-prefix 3 ; default value 0. Valid value 0-60. By default (value 0) NLSR adds
; all available faces for each reachable name prefixes in NDN FIB
}
; the advertising section contains the configuration settings of the
name prefixes ; hosted by this router
advertising
{
; the ndnname is used to advertised name from the router. To advertise each name prefix
; configure one block of ndnname configuration command for every name prefix.
prefix /ndn/memphis/sports/basketball/grizzlies
prefix /ndn/memphis/entertainment/blues
prefix /ndn/news/memphis/politics/lutherking
}
By default NLSR’s sequence file directory is set to /var/lib/nlsr/. User must create this
directory before starting NLSR. Since this is a system directory, NLSR must either be executed
as root, or NLSR can be run as user “nlsr” after configuring the filesystem to grant “nlsr”
read and write permissions. If user lacks permissions, the following error will occur:
User does not have read and write permission on the directory
Error in configuration file processing! Exiting from NLSR
To avoid this, the directory can be set in a user-owned directory. For example:
general
{
...
state-dir /home/username/nlsr/log ; path for sequence directory and other dynamic changes (Absolute path)
}
...
The user will encounter errors such as the following if security is not configured:
Cannot read certificate from file: /home/username/NLSR/root.cert
To get rid of this and similar errors relating to security one has to configure security as described in Security Configuration. Security can be disabled for testing purposes as follows:
...
trust-anchor
{
type any
;file-name "root.cert"
}
...
trust-anchor
{
type any
;file-name "site.cert"
}
; cert-to-publish "root.cert"
; cert-to-publish "router.cert"
; cert-to-publish "site.cert"
; cert-to-publish "router.cert"
Or by simply replacing the whole security section with:
security
{
validator
{
trust-anchor
{
type any
}
}
prefix-update-validator
{
trust-anchor
{
type any
}
}
}
Step 4: Running NLSR on /ndn/memphis.edu/router1¶
Assuming the configuration file is saved as nlsr.conf, type the following to run nlsr:
$ nlsr -f nlsr.conf
NLSR will look for nlsr.conf in the current directory. If nlsr.conf is not in the current
directory, please provide the absolute path with the file name as the value. If
nlsr.conf resides in /home/ndnuser/configuration directory, type nlsr -f
/home/ndnuser/configuration/nlsr.conf to run nlsr.
The same process needs to be followed for /ndn/arizona.edu/router3 and
/ndn/colostate.edu/router2 to run NLSR on these routers.
Expected Output¶
Assuming that all three routers are configured correctly and routing has converged,
nfd-status in /ndn/edu/colostate/%C1.Router/router2 will have the following (or similar)
entries for the name advertised by /ndn/edu/memphis/%C1.Router/router1:
RIB:
/ndn/memphis/entertainment/blues route={faceid=17 (origin=128 cost=25 ChildInherit), faceid=7 (origin=128 cost=58 ChildInherit)}
/ndn/memphis/sports/basketball/grizzlies route={faceid=17 (origin=128 cost=25 ChildInherit), faceid=7 (origin=128 cost=58 ChildInherit)}
/ndn/news/memphis/politics/lutherking route={faceid=17 (origin=128 cost=25 ChildInherit, faceid=7 (origin=128 cost=58 ChildInherit)}
This output can be seen by typing nfdc route list in the terminal. Please refer to the
network figure for face IDs.