Cisco Ccna Certification Exam Tutorial Distance Vector Command Review

Cisco Ccna Certification Exam Tutorial Distance Vector Command Review



Cisco CCNA Certification Exam Tutorial: Distance Vector Command Review
Part of​ studying for CCNA exam success is​ keeping all these new commands straight in​ your head! And let's face it, there are a​ lot of​ commands you need to​ know in​ order to​ pass the CCNA exam and earn that certification .​
Here's a​ review of​ some very important distance vector and static routing commands you need to​ know, along with their proper usage and console output.
Bandwidth
IGRP makes a​ default assumption that any Serial interface running IGRP is​ connected to​ a​ T1 line, which runs at​ 1544 KBPS .​
With equal-cost load-balancing enabled by default, this may be an​ undesirable assumption.
To alter IGRP’s assumption, use the bandwidth command on the serial interface in​ question .​
Note that this command does NOT actually affect the bandwidth available to​ the interface; it​ merely changes IGRP’s assumption of​ the bandwidth.
R2#conf t
R2(config)#int s0
R2(config-if)#bandwidth 512
Clear ip route *
This command clears your routing table of​ all non-static and non-connected routes .​
In a​ lab environment, it’s very handy because it​ forces your routers running routing protocols to​ send and request updates, rather than waiting for the regularly scheduled updates.
R2#clear ip route *
Debug ip igrp events
Debug ip igrp events allows you to​ see IGRP updates being sent and requested .​
Here, the debug is​ run and then the routing table is​ cleared .​
The router immediately broadcasts update requests via the IGRP-enabled interfaces.
R2#debug ip igrp event
IGRP event debugging is​ on
R2#clear ip route *
06:02:51: IGRP: broadcasting request on BRI0
06:02:51: IGRP: broadcasting request on Serial0.123
Debug ip igrp transactions
To configure IGRP unequal-cost load-sharing with the variance command, you’ve got to​ know the metric of​ the less-desirable routes .​
EIGRP keeps these in​ its topology table; IGRP has no such table.
To get the metrics of​ routes not in​ the routing table, run debug ip igrp transactions .​
To force IGRP updates, the routing table below was cleared with clear ip route *.
R2#debug ip igrp transactions
IGRP protocol debugging is​ on
R2#clear ip route *
06:05:33: IGRP: received update from 172.12.123.1 on Serial0.123
06:05:33: subnet 172.12.123.0, metric 10476 (neighbor 8476)
06:05:33: network 1.0.0.0, metric 8976 (neighbor 501)
06:05:33: IGRP: edition is​ now 3
06:05:33: IGRP: sending update to​ 255.255.255.255 via BRI0 (172.12.12.2)
06:05:33: network 1.0.0.0, metric=8976
06:05:33: IGRP: sending update to​ 255.255.255.255 via Serial0.123 (172.12.123.2) - suppressing null update
06:05:34: IGRP: received update from 172.12.12.1 on BRI0
06:05:34: subnet 172.12.13.0, metric 160250 (neighbor 8476)
06:05:34: network 1.0.0.0, metric 158750 (neighbor 501)
Debug ip rip
R2#debug ip rip
IP protocol debugging is​ on
R2#clear ip route *
6:14:53: RIP: received v2 update from 172.23.23.3 on Ethernet0
6:14:53: 1.0.0.0/8 via 0.0.0.0 in​ 16 hops (inaccessible)
6:14:53: 1.1.1.1/32 via 0.0.0.0 in​ 2 hops
6:14:53: 172.12.0.0/16 via 0.0.0.0 in​ 16 hops (inaccessible)
6:14:53: 172.12.12.2/32 via 0.0.0.0 in​ 2 hops
6:14:53: 172.12.13.0/30 via 0.0.0.0 in​ 1 hops
6:14:53: 172.12.123.0/24 via 0.0.0.0 in​ 1 hops
6:14:53: 172.23.0.0/16 via 0.0.0.0 in​ 16 hops (inaccessible)
Run debug ip rip to​ troubleshoot routing update problems, RIP authentication problems, and to​ view the routing update contents .​
Clear ip route * was run to​ clear the routing table and to​ force a​ RIP update .​
Ip route
R2#conf t
R2(config)#ip route 1.1.1.1 255.255.255.255 172.12.123.1
OR
R2(config)#ip route 1.1.1.1 255.255.255.255 serial0
To configure a​ static route to​ a​ given destination IP address, use the ip route command .​
The destination is​ followed by a​ subnet mask, and that can be followed by either the next-hop IP address or​ the exit interface on the local router.
Ip route 0.0.0.0 0.0.0.0
R2#conf t
R2(config)#ip route 0.0.0.0 0.0.0.0 172.12.123.1
OR
R2(config)#ip route 0.0.0.0 0.0.0.0 ethernet0
To configure a​ default static route, use either of​ these two commands.
You could have any number for the first 0.0.0.0, since the second set of​ zeroes is​ the subnet mask .​
This means that any destination will match this route statement .​
That's a​ good review to​ get started with! I'll be back tomorrow with Part II of​ this CCNA exam command review!




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