Does route table mix routes of different protocol?

johnifanx98

Say, a router has RIP and EIGRP run together, will I see mixed routes like "R" and "D" running "show ip route"?

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

Iristheangel

Yes. You'll also see connected and static routes

johnifanx98

Ok. Assume you understood my question, but just put wrong wording. My actual puzzle is: when an EIGRP sends update to its neighbor, it will send BW and delay of each EIGRP route. However, how does it determine BW/delay for those non-EIGRP route, like RIP?

Iristheangel

Perhaps I'm not understanding your question. EIGRP uses bandwidth and delay as part of it's calculation to determine it's metric, but other protocols don't use the same set of criteria to determine the metric for the routes. With RIP, it's a distance vector protocol so instead of using BW and delay, it uses hop count. If you're talking about redistributing a RIP route into EIGRP (which I don't believe is on the CCNA exam so I don't think you are asking this), you actually configure the metric during the redistribute command or configure a default metric. Again, route redistribution is outside of the scope of the CCNA exam so not sure if you're asking that or not

johnifanx98

Thanks a lot for your clarification. I was asking about redistribution. I doubt it's in icnd2, but just not certain.

Mrock4

It's important to realize that the EIGRP metric (bandwidth/delay by default as Iris said) is not sent with updates. It is a local value, known as the "K values" which is configured using the command "metric weights" command under router config mode. A router receives the metric from it's neighbor (which was derived from the neighbors bandwidth/delay).

YFZblu

johnifanx98 wrote: »

Thanks a lot for your clarification. I was asking about redistribution. I doubt it's in icnd2, but just not certain.

I don't remember Odom covering it, but I believe Lammle does.

theodoxa

1) Administrative Distance determines which routing protocol's route gets put in the table. If you receive IDENTICAL prefixes from EIGRP and RIP, the EIGRP route will get put in the routing table and not the RIP route because EIGRP has a default AD of 90 vs. RIP's 120.

2) If you are asking about redistribution...when you redistribute a route, you can specify the metric to be used or component values used to calculate the metric depending on the routing protocol.

Redistribution is covered in [CCNP] ROUTE.

instant000

johnifanx98:

Keep in mind that the routing table that you see from
"show ip route" only shows the BEST routes for each destination shown.

Each routing protocol makes its own table of valid routes.
That is, there is a RIP-specific table. "show ip rip database"
There is also an EIGRP-specific table: "show ip eigrp topology"

The FIB that you see from "show ip route" includes the collection of the valid longest-prefix, lowest-AD routes. that come from all the concerned input tables, and includes connected and static routes.

this is how this table is populated:
longest-prefix is preferred (most specific match to the route)
if that ties, then obviously, you want lowest AD (most trustworthy routing protocol for the route)
if that ties, then you want the lowest metric (most efficient route)
if you are still tied, load-balance (within routing protocol parameters, some allow you to fudge this, within constraints)

I am not sure if this was part of your question or not, but I hope it helps.

johnifanx98

I'm looking at IP internal route TLV. Both BW and delay are included.

EIGRP Packet Format | CCIE Certification Exam Lab,CCIE Security,Routing And Switching(R&S),Service Provider(SP),Voice Lab Workbook

Mrock4 wrote: »

It's important to realize that the EIGRP metric (bandwidth/delay by default as Iris said) is not sent with updates. It is a local value, known as the "K values" which is configured using the command "metric weights" command under router config mode. A router receives the metric from it's neighbor (which was derived from the neighbors bandwidth/delay).

johnifanx98

Instant, this does help really. I guess it also falls under the subject of redistribution.

instant000 wrote: »

johnifanx98:

Keep in mind that the routing table that you see from
"show ip route" only shows the BEST routes for each destination shown.

Each routing protocol makes its own table of valid routes.
That is, there is a RIP-specific table. "show ip rip database"
There is also an EIGRP-specific table: "show ip eigrp topology"

The FIB that you see from "show ip route" includes the collection of the valid longest-prefix, lowest-AD routes. that come from all the concerned input tables, and includes connected and static routes.

this is how this table is populated:
longest-prefix is preferred (most specific match to the route)
if that ties, then obviously, you want lowest AD (most trustworthy routing protocol for the route)
if that ties, then you want the lowest metric (most efficient route)
if you are still tied, load-balance (within routing protocol parameters, some allow you to fudge this, within constraints)

I am not sure if this was part of your question or not, but I hope it helps.