From: Toh Soon, Lim (tohsoon28@gmail.com)
Date: Thu Aug 16 2007 - 02:49:03 ART
Hi Sadiq,
Say, R1 & R2 are connected as follows:
R1 (Fa0/0) --------------- (Fa0/0) R2
Before I apply an offset-list on R1, R2 observes the following route in its
topo table:
R2#sh ip ei top 172.30.200.0 255.255.255.128
IP-EIGRP (AS 1): Topology entry for 172.30.200.0/25
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2174976
Routing Descriptor Blocks:
172.30.80.8 (FastEthernet0/0), from 172.30.80.8, Send flag is 0x0
Composite metric is (2174976/2172416), Route is Internal
Vector metric:
Minimum bandwidth is 1544 Kbit
Total delay is 20200 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 2
After I configured offset-list on R1 as follows:
!
router eigrp 1
offset-list 0 out 100 FastEthernet0/0
!
The 172.30.200.0/25 route on R2 becomes:
R2#sh ip ei top 172.30.200.0 255.255.255.128
IP-EIGRP (AS 1): Topology entry for 172.30.200.0/25
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2174976
Routing Descriptor Blocks:
172.30.80.8 (FastEthernet0/0), from 172.30.80.8, Send flag is 0x0
Composite metric is (2175076/2172516), Route is Internal
Vector metric:
Minimum bandwidth is 1544 Kbit
Total delay is 20203 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 2
The FD/AD values are increased by 100. Look at the cumulative delay; it's
20203 usec now, an increase of 3 usec. Where does this increase of 3 usec
come about? You said the offset value is added to the delay component. How
are they related here?
I suspect R1 adds 3 usec to its cumulative delay value when advertising the
route to R2. This will cause R2 to calculate an FD value that results in an
increase of 100. Can I sniff the UPDATE packets? Is there any debug command
that allows us to see the contents of the UPDATE packets? I have tried "deb
eigrp packet update" but no good.
Another thing that puzzles me is in the second output, the FD is 2174976 but
the CM is (2175076/2172516). In the RIB, the metric is 2175076.
D 172.30.200.0/25 [90/2175076] via 172.30.80.8, 00:13:57, FastEthernet0/0
Anyone, kindly enlighten me here.
Thank you.
Confused,
Lim TS
On 8/16/07, Sadiq Yakasai <sadiqtanko@gmail.com> wrote:
>
> Hi Toh,
>
> EIGRP offset list add the delay components on the composite metric
> addvertised either in or out of an interface.
>
> For example, if u configure an offset-list and add 1 to an inbound
> interface, all EIGRP routes learnt via that interface will increment
> the delay component of the route by 1, thereby incresing the total
> metric by 256.
>
> HTH
>
> Sadiq
This archive was generated by hypermail 2.1.4 : Sat Sep 01 2007 - 11:32:11 ART