EVPN Constructing Ethernet Segment Identifier (ESI)

[nkarpysh]

Hi All,

In scaled EVPN deployments it can be wise to name ESI that way to represent the site/physical port/etc it is attached to. Thus on some remote location you can easily verify where particular route/MAC is coming from. Similar to phone numbers, where you can locate the country/area/possibly a company of the caller. Thus we identified couple of ideas for it. That should ease support and structure deployments or new site integrations.

Q.
What is the best practice creating ESI?

A.
That is flexible however we can propose choosing smth like:

Variant 1:

aa.aa.aa.XX.XX.YY.YY.ZZ.ZZ

• ZZ.ZZ = Bundle ID 7777
• YY.YY = rack number
• XX.XX = Site ID

Example:

evpn

interface Bundle-Ether1177

  ethernet-segment

   identifier type 0 aa.aa.aa.03.33.11.22.11.77

Variant 2:

10.00.00.XX.YY.00.00.ZZ.ZZ

Where:

XX = REGION

YY = DC Number from Router Target in VRF Identifier

ZZ.ZZ = Bundle-Ethernet ID

Example:

10.00.00.12.01.00.00.77.77

P.S. Let us know your thoughts and ideas on how to do it better.

[RogerLienert15023]

I run multi-homed EVPN across a WAN and use the loopback IP address in the ESI to identify the PE routers connecting the ESI.

00.10.100.01.41.01.42.00.01

In this case, the ESI connects via 2 x PE's with loopback IP's of 10.100.1.41 and 10.100.1.42.

The rightmost .01 in the ESI represents the first ESI on this particular PE. If I configure a second ESI for another multi-homed network on this PE the last digits will be .02.

[nkarpysh]

Hi Roger,

If both PE are subject for same Multi-Homing domain then ESI should match, otherwise they will be considered as remote peers and wont be able to sync MAC/ARP (in case of IRB).

If you plan to embed IP into ESI then better it be an Anycast IP from BVI (IRB) if no IRB being used then posibly you can just drop the last octet from the IP.

Niko

[RogerLienert15023]

Hi Niko,

Yes these PEs are configured for multi-homing, I'm actually running single-flow-active across these as I have a ring of ethernet switches on the Access side.

I'm not using IRB, can you advise why you suggest to drop the last octet in teh ESI, do you see a problem with the format I am using?

I am using this format since it makes it easier to identify the PE's involved in the multi-homed EVPN.

Regards,

Roger

[nkarpysh]

If your IPs are unique then your ESI will be unique as well and it will make both PEs not to be peers. It will affect MAC sync and for SFA solution wont really work as it relies on same ESI id between peers