Hi
An issue came up when we were discussing optimizing the L1VPN auto
discovery information and also an implication if we move to multiple
domains.
For reference the current the L1VPN basic mode draft has:
(Client realm)
+----+ +----+
| |<Port Index> <Port Index> | |
| |CPI VPN-PPI | |
---| CE |-----------------------------| PE |---
| | <Port Index> | |
| | PPI | |
+----+ +----+
(Provider realm)
And the auto discovery information is documented as:
+---------------------------------------+
| Length (1 octet) |
+---------------------------------------+
| PPI Length (1 octet) |
+---------------------------------------+
| PPI (variable) |
+---------------------------------------+
| CPI AFI (2 octets) |
+---------------------------------------+
| CPI (length) |
+---------------------------------------+
| CPI (variable) |
+---------------------------------------+
When Signaling the procedure is to look up the remote CPI a the near end
PE and translates to a PPI for signaling purposes. If we were to extend
this information to multiple domains the PPI-CPI mapping would carry the
Provider address PPI outside the provider.
One way to optimize this is to carry only the CPI with a Route
Distinguisher, which is an 8 byte globally unique value.
Like this:
+---------------------------------------+
| Length (2 octets) |
+---------------------------------------+
| RD (8 octets) |
~ ~
+---------------------------------------+
| CPI1 (length 1 octet) |
+---------------------------------------+
| CPI1 (variable) |
+---------------------------------------+
| CPI2 (length 1 octet) |
+---------------------------------------+
| CPI2 (variable) |
+---------------------------------------+
| etc |
While the RD is larger the actual space for carrying multiple CPIs will
be reduced. The remote PE is inferred from the BGP Next Hop carried in
the auto-discovery routes. The information in these records is all
globally unique addressing information and independent of provider
attachment. This aligns with the other auto discovery schemes.
Note the PPI and VPN-PPI remain but are local information only.
This also implies a signaling change. The changes would include look up
CPI for a given RD, Signal to the destination associated PE and include
the RD and CPI in signaling to allow the destination PE to resolve the
customer port information.
We would like to solicit comments on these changes.
Thanks,
Don
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