Router ID with EIGRP for IPv4 vs IPv6?

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Hey ITPro! Can you guys clarify for me the significance of the router ID setting in EIGRP for IPv4 vs IPv6? In the show I watched Don seemed to ignore this setting when configuring IPv4 vs with the IPv6 show he was careful to set it. Was there a reason? What role in EIGRP does the router ID play?

I am pretty comfortable with the use of the router ID for OSPF at this point in determining DR/BDR if the priorities are the same.. I don't think I am confusing the two routing technologies, but let me know. Thanks.

Regards,
Adam Tyler

@Adam-Tyler said in Router ID with EIGRP for IPv4 vs IPv6?:

Hey ITPro! Can you guys clarify for me the significance of the router ID setting in EIGRP for IPv4 vs IPv6? In the show I watched Don seemed to ignore this setting when configuring IPv4 vs with the IPv6 show he was careful to set it. Was there a reason? What role in EIGRP does the router ID play?

I am pretty comfortable with the use of the router ID for OSPF at this point in determining DR/BDR if the priorities are the same.. I don't think I am confusing the two routing technologies, but let me know. Thanks.

Regards,
Adam Tyler

With EIGRP for IPv6, the Router ID continues to be represented by a 32 bit binary number. As a Router ID, it is not technically an IP Address.

Yes, but what is it for? Does it have some role like the Router-ID in OSPF where it helps determine DR/BDR (I realize these are OSPF specific roles.)? Why would it be important for IPv6 and not IPv4 implementations of IEGRP.

Regards,
Adam Tyler

@Adam-Tyler,

it is primarily for identification and differentiation of devices within the same EIGRP AS, as networks get larger it really is help. Also like OSPF, the router ID usually is tied to a loopback address so that when EIGRP starts up the first active interfaces (loopbacks) are ready to help establish all that EIGRP needs.There probably other uses for it too for example in the following article:
http://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/18685-eigrp-dup-id.html

Got it.. For identification and it is determined a lot like the OSPF router ID unless you hard code it.

-Adam

@Adam-Tyler,

If I remember correctly, exactly like OSPF does. First active-interface when the router process is turned on. Usually to keep the same one, we normally use a loopback address and assign them manually. When I worked with multiple routers ("Back in the Day, as we say here") I would always set a loopback ip of 1.1.1.1 255.255.255.255 for OSPF to the DR and 2.2.2.2 for the BDR. It's not that matters so much for EIGRP but if you want to easily identify which one to work on or which router had EIGRP configuration problems, the router-id was the easiest way to spot it.