Metrics Used When Redistributing Between Protocols

[srowles]

When redistributing between two routing protocols (OSPF and EIGRP) for example, providing that you do not wish to alter metrics to influence preferred routes, what metrics should you use.

For example if I am redistributing networks into eigrp and eigrp is running on a 64k frame relay connection should I use a metric of 64 20000 255 1 1500 providing that these are the values given when I perform a "show int s0" (S0 being the 64k frame relay connection)?

Again with OSPF, providing that I do not wish to manipulate metrics to affect route selection, when redistributing in to OSPF which is running on one interface with a cost of 50, should I use this cost of 50 when performing the redistribution.

Any comments would be appreciated.

[daniel.bowen]

I may not be understanding your question right, but OSPF will simply supply a metric for cost, as it has no real understanding of bandwidth, delay etc. You should always use the metric that favours the recieving router. For arguments sake, if you are redistributing EIGRP into OSPF, use the OSPF metric. The reason for this is that OSPF will need to make the routing decision on the new network, so it is easier if it favours OSPF.

If this was not what you were asking, try and explain it again and I will have another go.

Daniel,

[srowles]

Thanks Daniel.. What I am trying to get at is :

Perhaps this scenario will better explain what I am tring to determine:

I have a router with two serial interfaces, one running eigrp and one running ospf.

I perform a "show int" on the interface running eigrp and get the following information:

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255

When I redistribute ospf int eigrp should I use: EIGRP 1

REDISTRIBUTE OSPF METRIC 1544 20000 255 1 1500

which matches the values shown on the interface.

Also if I perform a "show ip ospf int" on the interface that is running ospf I am given the value :

Cost: 64

Therefore when redistributing eigrp into ospf should I use:

Router ospf 1

redistribute eigrp 1 metric 64

Steve

[daniel.bowen]

Yes Steve, that is correct. I do apologise for making this more complicated than it was.

Daniel,

[srowles]

Thanks for the help

Steve

[svermill]

In the case of EIGRP, I think you need to adjust your delay value. The 'sh int' command displays delay in microseconds. The EIGRP metric format is delay in tens of microseconds. So I suspect that your value should be 2000 rather than 20000.

[srowles]

Thanks, that does seem to be the case.