Common addresses

There are about a dozen MAC addresses and a dozen multicast addresses one should recognize. A good example are the multicast IP addresses used by RIP, IGRP, EIGRP, PIM, and OSPF.. or the multicast MAC addresses used by IS-IS, LACP, STP, etc. Many of these are etched in my brain because I work with them often. Some, less so, especially if I haven't troubleshot them lately.

Do you have any good tricks or mnemonics for memorizing these?

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Comments

gorebrush

I just remember them...

I think I'm up to about 6 of them. The really nice thing is, the kinds folks who designed IPv6 kept the same numbers, so

224.0.0.5 and 224.0.0.6 = OSPF
FF02::5 and 6 = OSPF

I quite like that.

NetworkVeteran

gorebrush wrote:

The really nice thing is, the kinds folks who designed IPv6 kept the same numbers, so

Yup! The IPv6 part I don't worry about, besides its unique address ranges (e.g., 6to4, NAT64, etc.).

down77

There is no secret trick to memorizing this other than practice practice practice! I wish I could give a better answer.

NetworkVeteran

My favorite is IS-IS with its four common MAC addresses!

09-00-2B-00-00-04, 09-00-2B-00-00-05, 01-80-C2-00-00-14, & 01-80-C2-00-00-15.

NetworkVeteran

Protocol Addresses

L2 - 01-80-C2-00-00-xx

00 STP*
01 Flow Control*
03 802.1X*
07 E-LMI
0E LLDP*
14 IS-IS L1 IS
15 IS-IS L2 IS

L2 - 09-00-2B-00-00-xx

04 IS-IS All ES
05 IS-IS All IS

L3 - 224.0.0.x

01 All Systems*
02 All Routers*
05 OSPF All Routers*
06 OSPF Designated Routers*
09 RIP*
10 IGRP/EIGRP*
13 PIM*
18 VRRP*
22 IGMPv3*

* = Relevant to CCIE.

NetworkVeteran

Alright! Sounds like not much to do here but to prioritize and double-up my flash cards (solve forward and reverse).

I will get this down.

powmia

In addition to MACs and Multicast addresses, I highly recommend adding ethertypes to your flash cards. Most important are the values 0x806, 0x800, 0x86DD, 0x8100, and the not really 'ether' ethertypes 0x4242, 0x010B and 0xAAAA. Regarding the IPv6 Multicast, you probably won't need these for your CCIE, but they're good reads anyways - RFC 4291 section 2.7.1 ; RFC 3306 ; RFC 3956 (those are the T, P, and R flags, respectively. Sorry if that's a distraction from the relevant.

NetworkVeteran

Great tip! The only etherTypes I had in my cards were 0x8847 & 0x8848. I've now incorporated the others in.