Is anyone else looking at using this feature?
I have been simply trying to work a simple example of how it
could be used for an exchange point LSR (crazy me, heh?)
In practice, it feels wierd to build multiple LSPs to the same
adjacent "stitching LSR", each handling a different static
("installed") route; but this is necessary since the stitching
binds each LSP to a different destination.
The only nice thing is that the BR's only would have to do RSVP with
the Exchange LSR, not with each other, right?
However, what happens to LSP up/down state? Does the stitching router
make sure both sides of the stitch know if either side goes inactive?
Operationally, this approach requires the exchange to explicitly
configure each peer pair, ala ATM exchange points. For the open
peering of GigE-type exchange points, an Exchange LSR wouldn't
use CCC, BR's could RSVP signal thru a relatively passive exchange LSR
to each other, and set up their own peering LSPs on the fly. This
seems to have inter-domain RSVP policy issues.
So for a simple example:
Consider a border router AS10 that wants to talk to two other
BRs (AS20, AS30) across an exchange LSR:
/-----------AS20
.6 / x.x.x.5/30
AS10 -----------ExchangeLSR
x.x.x.1/30 .2 .10 \
\-----------AS30
x.x.x.9/30
Physical Links:
AS10<->ExLSR: x.x.x.1/30-x.x.x.2/30
AS20<->ExLSR: x.x.x.5/30-x.x.x.6/30
AS30<->ExLSR: x.x.x.9/30-x.x.x.10/30
AS10:
# to talk to AS20
label-switched-path LSP-1 {
to x.x.x.2;
install x.x.x.5 active;
no-decrement-ttl;
nocspf;
}
# to talk to AS30
label-switched-path LSP-2 {
to x.x.x.2;
install x.x.x.9 active;
no-decrement-ttl;
nocspf;
}
AS20:
# to talk to AS10
label-switched-path LSP-3 {
to x.x.x.6;
install x.x.x.1 active;
no-decrement-ttl;
nocspf;
}
AS30:
# to talk to AS10
label-switched-path LSP-4 {
to x.x.x.10;
install x.x.x.1 active;
no-decrement-ttl;
nocspf;
}
Exchange LSR:
# LSPs req'd: one for each lsp-switch, in pseudocode:
# note the need for two LSP's to .1
LSP-5 to .1
LSP-6 to .1
LSP-7 to .5
LSP-8 to .9
# stitch AS10<->AS20
lsp-switch as20->as10 {
transmit-lsp LSP-5;
receive-lsp LSP-3;
}
lsp-switch as10->as20 {
transmit-lsp LSP-7;
receive-lsp LSP-1;
}
# stitch AS10<->AS30
lsp-switch as30->as10 {
transmit-lsp LSP-6;
receive-lsp LSP-4;
}
lsp-switch as10->as30 {
transmit-lsp LSP-8;
receive-lsp LSP-2;
}
Lane Patterson <lane@equinix.com>
Member Research Staff
Equinix, Inc.
(650) 316-6012
This archive was generated by hypermail 2b29 : Mon Aug 05 2002 - 10:42:43 EDT