Internet Standards/CD1.mdf/MISC/MERIT/1991/91_272.PS

Text File | 1991-09-12 | 33.8 KB | 1,499 lines

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%%Page: 1 1
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F1 sF
720 7524 M
2 39 1518 (Additional IDRP Comments) BWS
4755 7524 M
765 (X3S3.3/91-272) WS
720 7212 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F3 sF
720 6303 M
222 (Title:) WS
F0 sF
543 0 RM
5 33 1926 (Additional Comments on CD 10747 \(IDRP\)) BWS
F3 sF
720 6117 M
351 (Source:) WS
F0 sF
414 0 RM
3 33 1146 (IBM and Merit Computer) BWS
720 5931 M
2 51 180 ( 1. ) BWS
F4 sF
552 (Precedence) WS
33 0 RM
84 (of) WS
33 0 RM
285 (Match) WS
33 0 RM
195 (with) WS
33 0 RM
366 (Longest) WS
33 0 RM
267 (Prefix) WS
33 0 RM
180 (\(M\):) WS
-2127 0 RM
0 -15 RM
6 LW
cP /sY xdef /sX xdef
2127 0 rL
sX sY M
F0 sF
900 5745 M
16 33 4494 (In reviewing the text, it was discovered that there is no normative text in the Forwarding Process) BWS
900 5622 M
15 33 4470 (that explicitly states that an NPDU shall be forwarded based on the longest NSAP address prefix) BWS
900 5499 M
16 33 4326 (match, even though it is common knowledge that this is how the process is intended to work.) BWS
900 5313 M
11 33 3414 (Therefore, the first paragraph of clause 9.4 should be changed as follows:) BWS
1080 5127 M
8 33 3570 (...matches the NPDU-derived Distinguishing Attributes of the incoming NPDU.) BWS
F5 sF
66 0 RM
1 33 618 (The incoming) BWS
1080 5004 M
13 33 4056 (NPDU shall be forwarded based on the longest NSAP address prefix which matches \(see) BWS
1080 4881 M
8 33 2793 (8.1.2.2\) the destination NSAP address of the incoming NPDU:) BWS
F0 sF
720 4695 M
2 51 180 ( 2. ) BWS
F4 sF
408 (Handling) WS
33 0 RM
84 (of) WS
33 0 RM
561 (Overlapping) WS
33 0 RM
318 (Routes) WS
33 0 RM
180 (\(M\):) WS
-1683 0 RM
0 -15 RM
cP /sY xdef /sX xdef
1683 0 rL
sX sY M
F0 sF
900 4509 M
17 33 4329 (Within the framework of IDRP, it is possible for a BIS to advertise a set of overlapping routes.) BWS
66 0 RM
123 (All) WS
900 4386 M
15 33 4605 (routes in such a set have the same distinguishing attributes, and the respective NLRI contain desti-) BWS
900 4263 M
13 33 4329 (nations in common. Since NLRI depicts destinations by means of NSAP address prefixes, this) BWS
900 4140 M
11 33 3036 (means that some of the prefixes will be nested inside each other.) BWS
900 3954 M
15 33 4365 (Since the forwarding process selects a next hop for an NPDU based on longest NSAP address) BWS
900 3831 M
4 33 1368 (prefix that matches the NPDU) BWS
S0 sF
30 (\242) WS
F0 sF
12 33 3084 (s destination address field, there is no ambiguity even if a BIS has) BWS
900 3708 M
6 33 2466 (advertised several routes with nested NSAP prefixes.) BWS
66 0 RM
6 33 2076 (However, IDRP contains no normative text to) BWS
900 3585 M
14 33 4491 (insure that the Decision Process will handle overlapping routes in a way that accurately portrays) BWS
900 3462 M
9 33 2634 (the actions that will be taken by the Forwarding Process.) BWS
66 0 RM
6 33 1773 (For example, nothing in CD 10747 pre-) BWS
900 3339 M
16 33 4272 (vents a BIS from accepting from a given neighbor BIS only the route with the shortest NSAP) BWS
900 3216 M
13 33 4425 (address prefix, while rejecting routes from the same neighbor that have longer nested prefixes.) BWS
900 3030 M
11 33 3507 (Therefore, we recommend that normative text should be added to CD 10747) BWS
S0 sF
30 (\242) WS
F0 sF
3 33 888 (s description of the) BWS
900 2907 M
10 33 3198 (Decision Process to define how a BIS will handle overlapping routes.) BWS
66 0 RM
4 33 1158 (The following text is sug-) BWS
900 2784 M
336 (gested:) WS
F3 sF
1080 2598 M
2 33 1188 (8.15.3 Route Replacement) BWS
F0 sF
1080 2412 M
15 33 4224 (If an UPDATE PDU is received carrying a route that matches an earlier route received from) BWS
1080 2289 M
13 33 4188 (the same BIS \(identical NLRI and distinguishing attributes\), the new route replaces the old) BWS
1080 2166 M
13 33 4140 (route, which becomes unfeasible, and the old route shall be deleted from the appropriate) BWS
1080 2043 M
378 (Adj-RIB.) WS
F3 sF
1080 1857 M
2 33 1275 (8.17.2.1 Overlapping Routes) BWS
F0 sF
1080 1671 M
12 33 3969 (A BIS may transmit overlapping routes to another BIS \(routes with overlapping NLRI\).) BWS
66 0 RM
222 (NLRI) WS
1080 1548 M
13 33 4188 (overlaps when a set of destinations are identified in non-matching multiple routes with the) BWS
1080 1425 M
4 33 1707 (same set of distinguishing attributes.) BWS
66 0 RM
6 33 2328 (Since IDRP encodes NLRI using prefixes, overlaps) BWS
1080 1302 M
4 33 1836 (will always exhibit subset relationships.) BWS
66 0 RM
8 33 2325 (A route describing a smaller set of destinations \(a) BWS
1080 1179 M
5 33 1221 (longer prefix\) is said to be) BWS
F5 sF
2 33 642 ( more specific) BWS
F0 sF
9 33 2388 ( than a route describing a larger set of destinations) BWS
1080 1056 M
2 33 804 (\(a shorter prefix\).) BWS
720 528 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F2 sF
720 363 M
2 39 1086 (September 12, 1991) BWS
5457 363 M
63 (1) W1
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SS
F1 sF
720 7524 M
2 39 1518 (Additional IDRP Comments) BWS
4755 7524 M
765 (X3S3.3/91-272) WS
720 7212 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F0 sF
1080 6858 M
13 33 4227 (When overlapping routes are transmitted from one BIS to another, the more specific routes) BWS
1080 6735 M
10 33 3111 (shall take precedence, in order from most specific to least specific.) BWS
1080 6549 M
10 33 4068 (This precedence relationship effectively decomposes less specific routes into two parts:) BWS
S6 sF
1146 6372 M
36 (\267) WS
F0 sF
78 0 RM
0 -9 RM
11 33 3069 (a set of destinations described only by the less specific route, and) BWS
S6 sF
1146 6186 M
36 (\267) WS
F0 sF
78 0 RM
0 -9 RM
15 33 4047 (a set of destinations described by the overlap of the less specific and the more specific) BWS
1260 6054 M
291 (routes) WS
1080 5868 M
15 33 4059 (The set of destinations described by the overlap comprise a feasible route that is not in) BWS
1080 5745 M
192 (use.) WS
66 0 RM
14 33 3870 (If a more specific route is later advertised as being unreachable, the set of destina-) BWS
1080 5622 M
13 33 3825 (tions described by the overlap will then be reachable using the less specific route.) BWS
1080 5436 M
14 33 4161 (If a BIS receives overlapping routes, the Decision Process shall not alter the semantics of) BWS
1080 5313 M
2 33 1071 (the overlapping routes.) BWS
66 0 RM
11 33 2958 (In particular, a BIS shall not accept the less specific route while) BWS
1080 5190 M
12 33 4197 (rejecting the more specific route, because the destinations represented by the overlap will) BWS
1080 5067 M
5 33 1584 (not be forwarded along that route.) BWS
66 0 RM
6 33 1986 (Therefore, a BIS has the following choices:) BWS
1080 4881 M
2 51 456 ( 1. Install) BWS
33 0 RM
201 (both) WS
33 0 RM
144 (the) WS
33 0 RM
186 (less) WS
33 0 RM
171 (and) WS
33 0 RM
240 (more) WS
33 0 RM
348 (specific) WS
33 0 RM
291 (routes) WS
1080 4695 M
2 51 456 ( 2. Install) BWS
33 0 RM
144 (the) WS
33 0 RM
240 (more) WS
33 0 RM
348 (specific) WS
33 0 RM
240 (route) WS
33 0 RM
192 (only) WS
1080 4509 M
2 51 456 ( 3. Install) BWS
33 0 RM
144 (the) WS
33 0 RM
747 (non-overlapping) WS
33 0 RM
183 (part) WS
33 0 RM
84 (of) WS
33 0 RM
144 (the) WS
33 0 RM
186 (less) WS
33 0 RM
348 (specific) WS
33 0 RM
240 (route) WS
33 0 RM
192 (only) WS
1080 4323 M
2 51 660 ( 4. Aggregate) BWS
33 0 RM
144 (the) WS
33 0 RM
162 (two) WS
33 0 RM
291 (routes) WS
33 0 RM
171 (and) WS
33 0 RM
276 (install) WS
33 0 RM
144 (the) WS
33 0 RM
525 (aggregated) WS
33 0 RM
240 (route) WS
1080 4137 M
2 51 456 ( 5. Install) BWS
33 0 RM
324 (neither) WS
33 0 RM
240 (route) WS
720 3951 M
2 51 180 ( 3. ) BWS
F4 sF
519 (Elimination) WS
33 0 RM
84 (of) WS
33 0 RM
321 (Nested) WS
33 0 RM
264 (NSAP) WS
33 0 RM
375 (Address) WS
33 0 RM
372 (Prefixes) WS
33 0 RM
126 (\(E\)) WS
-2259 0 RM
0 -15 RM
6 LW
cP /sY xdef /sX xdef
2259 0 rL
sX sY M
F0 sF
900 3765 M
17 33 4599 (Since it is always possible to replace a set of routes having nested NSAP prefixes by an equivalent) BWS
900 3642 M
13 33 4503 (set without nested prefixes, IBM suggests that an informative annex describing such a procedure) BWS
900 3519 M
2 33 789 (would be helpful.) BWS
66 0 RM
14 33 3669 (To accomplish this, we suggest adding the following note at the end of the new) BWS
900 3396 M
15 33 4578 (suggested text for 8.17.2.1 \(above\), and then adding a new informative annex, using the text shown) BWS
900 3273 M
2 33 672 (in Appendix Z:) BWS
F3 sF
1080 3087 M
237 (Note:) WS
F0 sF
84 0 RM
12 33 3846 (Procedures exist to transform any set of routes with nested NSAP address prefixes) BWS
1401 2964 M
8 33 2634 (into an equivalent set of routes with non-nested prefixes.) BWS
66 0 RM
4 33 1182 (A description of one such) BWS
1401 2841 M
5 33 1407 (technique is given in Annex Z.) BWS
66 0 RM
12 33 2304 (A BIS is free to choose to do so as a local option,) BWS
1401 2718 M
13 33 3840 (should it feel that such an approach is preferable to explicit storage and advertise-) BWS
1401 2595 M
7 33 2361 (ment of routes with nested NSAP address prefixes.) BWS
720 2409 M
2 51 180 ( 4. ) BWS
F4 sF
228 (IDRP) WS
33 0 RM
333 (ERROR) WS
33 0 RM
201 (PDU) WS
33 0 RM
150 (\(m\)) WS
-1011 0 RM
0 -15 RM
cP /sY xdef /sX xdef
1011 0 rL
sX sY M
F0 sF
900 2223 M
16 33 4464 (The ERROR PDU is difficult to parse because the presence or absence of the Error Subcode and) BWS
900 2100 M
4 33 1464 (Data Fields is context sensitive.) BWS
66 0 RM
8 33 2904 (Therefore, the Error Subcode field should be made mandatory,) BWS
900 1977 M
7 33 1308 (with a value of 0 defined as ) BWS
S0 sF
42 (\262) WS
F0 sF
858 (No_Error_Subcode) WS
S0 sF
69 (\262.) WS
F0 sF
900 1791 M
9 33 2322 (An editorial correction is needed in 7.4 to change ) BWS
S0 sF
42 (\262) WS
F0 sF
675 (NOTIFICATION) WS
S0 sF
1 33 75 (\262 ) BWS
F0 sF
1 33 120 (to ) BWS
S0 sF
42 (\262) WS
F0 sF
2 33 834 (IDRP ERROR PDU) BWS
S0 sF
1 33 75 (\262 ) BWS
F0 sF
1 33 261 (in the) BWS
900 1668 M
2 33 876 (section describing ) BWS
S0 sF
42 (\262) WS
F0 sF
213 (Data) WS
S0 sF
69 (\262.) WS
F0 sF
720 1482 M
2 51 180 ( 5. ) BWS
F4 sF
405 (Attribute) WS
33 0 RM
504 (Numbering) WS
33 0 RM
123 (\(e\)) WS
-1098 0 RM
0 -15 RM
cP /sY xdef /sX xdef
1131 0 rL
sX sY M
F0 sF
900 1296 M
12 33 3420 (There is inconsistent numbering of path attribute types in 7.4 and Table 1.) BWS
66 0 RM
2 33 789 (The existing type) BWS
900 1173 M
11 33 4590 (numbers should be corrected as follows: SS SEC=17, DS SEC=18, CAPACITY=19, PRIORITY=20.) BWS
900 1050 M
14 33 4212 (The editor should also assure that the remainder of the text is also numbered consistently.) BWS
720 864 M
2 51 180 ( 6. ) BWS
F4 sF
213 (RDIs) WS
33 0 RM
123 (\(e\)) WS
-369 0 RM
0 -15 RM
cP /sY xdef /sX xdef
402 0 rL
sX sY M
720 528 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F2 sF
720 363 M
2 39 1086 (September 12, 1991) BWS
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SS
F1 sF
720 7524 M
2 39 1518 (Additional IDRP Comments) BWS
4755 7524 M
765 (X3S3.3/91-272) WS
720 7212 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F0 sF
900 6858 M
11 33 2865 (The use of length fields with respect to RDIs is not consistent.) BWS
66 0 RM
6 33 1632 (In particular, the OPEN PDU uses a) BWS
900 6735 M
10 33 4197 (length in octets, while the DIST_LIST_INCL and DIST_LIST_EXCL attributes use semioctets.) BWS
900 6549 M
11 33 3204 (Since RDIs must be valid NSAPs, they are always encoded as octets.) BWS
66 0 RM
4 33 1236 (Thus the description of the) BWS
900 6426 M
13 33 4368 (DIST_LIST_EXCL and DIST_LIST_INCL attributes on page 15 should be changed to say that the) BWS
900 6303 M
3 33 849 (length is in octets.) BWS
900 6117 M
3 33 1056 (Furthermore, the term ) BWS
S0 sF
42 (\262) WS
F0 sF
1 33 456 (RDI prefix) BWS
S0 sF
1 33 75 (\262 ) BWS
F0 sF
7 33 1923 (occurs at least in these same two places.) BWS
66 0 RM
3 33 846 (This term is incor-) BWS
900 5994 M
9 33 2685 (rect; RDIs are not prefixes, nor are they ever abbreviated.) BWS
66 0 RM
2 33 450 (The term ) BWS
S0 sF
42 (\262) WS
F0 sF
165 (RDI) WS
S0 sF
1 33 75 (\262 ) BWS
F0 sF
2 33 717 (should replace ) BWS
S0 sF
42 (\262) WS
F0 sF
165 (RDI) WS
900 5871 M
258 (prefix) WS
S0 sF
1 33 75 (\262 ) BWS
F0 sF
2 33 888 (wherever it occurs.) BWS
720 5685 M
2 51 180 ( 7. ) BWS
F4 sF
486 (Suggested) WS
33 0 RM
174 (text) WS
33 0 RM
87 (in) WS
33 0 RM
435 (Appendix) WS
33 0 RM
69 (A) W1
33 0 RM
84 (of) WS
33 0 RM
288 (91-223) WS
-1821 0 RM
0 -15 RM
6 LW
cP /sY xdef /sX xdef
1821 0 rL
sX sY M
F3 sF
900 5499 M
237 (Note:) WS
F0 sF
84 0 RM
17 33 4146 (This is not a comment on IDRP; it is a comment aimed at improving the text suggested in) BWS
1221 5376 M
5 33 1836 (prior IBM comment 91-223, Appendix A.) BWS
900 5190 M
10 33 3327 (The comparison process called out by the suggested replacement text \() BWS
S0 sF
42 (\262) WS
F0 sF
4 33 1131 (pick the NET with lowest) BWS
900 5067 M
249 (value) WS
S0 sF
1 33 108 (\262\) ) BWS
F0 sF
11 33 3681 (is underspecified, because encoded versions of NETs can be of variable length.) BWS
66 0 RM
1 33 459 (To handle) BWS
900 4944 M
13 33 4575 (such situations unambiguously, it is recommended that it be required, for purposes of comparison,) BWS
900 4821 M
17 33 4509 (to pad the NET with trailing semi-octets up to the maximum encoded length of an NET, namely 20) BWS
900 4698 M
303 (octets.) WS
720 528 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F2 sF
720 363 M
2 39 1086 (September 12, 1991) BWS
5457 363 M
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SS
F1 sF
720 7524 M
2 39 1518 (Additional IDRP Comments) BWS
4755 7524 M
765 (X3S3.3/91-272) WS
720 7212 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
720 6873 M
30 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F8 sF
720 6708 M
1 60 915 (Appendix Z.) BWS
120 0 RM
4 60 3231 (Transforming Nested Prefixes into Disjoint) BWS
720 6516 M
609 (Prefixes) WS
F3 sF
2826 6213 M
585 (\(Informative\)) WS
720 5958 M
6 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F9 sF
720 5817 M
204 (Z.1) WS
108 0 RM
3 54 2526 (Decomposition of Elementary Routes) BWS
F0 sF
720 5541 M
6 33 1584 (An NSAP address prefix of length ) BWS
F5 sF
69 (K) W1
F0 sF
10 33 2985 ( semi-octets can be decomposed into 16 prefixes, each of length) BWS
F5 sF
720 5418 M
1 24 93 (K ) BWS
S7 sF
1 24 102 (+ ) BWS
F0 sF
51 (1) W1
33 0 RM
108 (by) WS
33 0 RM
483 (appending) WS
33 0 RM
144 (the) WS
33 0 RM
585 (hexadecimal) WS
33 0 RM
300 (values) WS
33 0 RM
51 (0) W1
33 0 RM
354 (through) WS
33 0 RM
54 (F) W1
33 0 RM
87 (to) WS
33 0 RM
144 (the) WS
33 0 RM
171 (end) WS
33 0 RM
84 (of) WS
33 0 RM
144 (the) WS
33 0 RM
348 (original) WS
33 0 RM
285 (prefix.) WS
720 5172 M
15 33 4713 (Therefore, an elementary route can be decomposed into an equivalent set of 16 elementary routes by) BWS
720 5049 M
15 33 4449 (decomposing the NSAP address prefix of the original route and setting the path attributes of the) BWS
720 4926 M
10 33 3174 (decomposed routes equal to the path attributes of the original route.) BWS
720 4671 M
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F9 sF
720 4530 M
204 (Z.2) WS
108 0 RM
3 54 2367 (Composition of Elementary Routes) BWS
F0 sF
720 4254 M
10 33 2340 (A set of 16 NSAP address prefixes, each of length ) BWS
F5 sF
69 (K) W1
F0 sF
8 33 2181 (, can be composed into a single NSAP address) BWS
720 4131 M
4 33 1017 (prefix prefix of length ) BWS
F5 sF
69 (K) W1
S7 sF
24 0 RM
78 (-) W1
F0 sF
24 0 RM
16 33 3429 (1 if each semi-octet in the range 0 to F is present as the last semi-octet of) BWS
720 4008 M
6 33 1425 (one of the members of the set.) BWS
66 0 RM
13 33 3126 (If there is a set of 16 elementary routes with the same length NSAP) BWS
720 3885 M
14 33 4746 (prefixes, but possibly with different path attributes, and their NSAP address prefixes be composed into) BWS
720 3762 M
19 33 4647 (a single prefix, then the 16 original routes can be replaced by a smaller number of routes by the fol-) BWS
720 3639 M
1 33 831 (lowing procedure:) BWS
720 3453 M
2 51 375 ( 1. Find) BWS
33 0 RM
144 (the) WS
33 0 RM
318 (largest) WS
33 0 RM
303 (subset) WS
33 0 RM
210 (from) WS
33 0 RM
315 (among) WS
33 0 RM
144 (the) WS
33 0 RM
102 (16) WS
33 0 RM
291 (routes) WS
33 0 RM
297 (whose) WS
33 0 RM
435 (members) WS
33 0 RM
222 (have) WS
33 0 RM
144 (the) WS
33 0 RM
252 (same) WS
33 0 RM
201 (path) WS
33 0 RM
462 (attributes.) WS
720 3267 M
2 51 555 ( 2. Replace) BWS
33 0 RM
165 (this) WS
33 0 RM
303 (subset) WS
33 0 RM
189 (with) WS
33 0 RM
57 (a) W1
33 0 RM
276 (single) WS
33 0 RM
240 (route) WS
33 0 RM
297 (whose) WS
33 0 RM
264 (NSAP) WS
33 0 RM
369 (address) WS
33 0 RM
258 (prefix) WS
33 0 RM
78 (is) WS
33 0 RM
474 (composed) WS
33 0 RM
84 (of) WS
33 0 RM
144 (the) WS
33 0 RM
264 (NSAP) WS
900 3144 M
15 33 4473 (address prefixes of the 16 routes \(and thus is one semi-octet shorter\), and whose path attributes) BWS
900 3021 M
12 33 2910 (are the same as the path attributes of the routes in the subset.) BWS
720 2835 M
2 51 420 ( 3. Keep) BWS
33 0 RM
111 (all) WS
33 0 RM
144 (the) WS
33 0 RM
465 (remaining) WS
33 0 RM
291 (routes) WS
33 0 RM
279 (intact.) WS
720 2580 M
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F9 sF
720 2439 M
204 (Z.3) WS
108 0 RM
4 54 2895 (Constructing and Dismantling Prefix Trees) BWS
F0 sF
720 2163 M
9 33 2148 (Each node of an NSAP address prefix tree \(or ) BWS
F5 sF
1 33 468 (prefix tree) BWS
F0 sF
8 33 2121 (, for short\) has a single prefix associated with) BWS
720 2040 M
16 33 4557 (it; furthermore, every non-leaf node has the property that the prefixes of all its children are nested) BWS
720 1917 M
3 33 954 (within its own prefix.) BWS
720 1671 M
16 33 4791 (If there are several routes with nested NSAP address prefixes, the semantics of this information can be) BWS
720 1548 M
14 33 4665 (determined by constructing and then dismantling a prefix tree for the nested NSAP address prefixes.) BWS
720 1425 M
15 33 4533 (This recursive procedure replaces a set of routes whose NSAP address prefixes are nested by an) BWS
720 1302 M
10 33 3249 (equivalent set of routes whose NSAP address prefixes are not nested.) BWS
66 0 RM
4 33 1308 (The procedure is as follows:) BWS
720 1116 M
2 51 540 ( 1. Starting) BWS
33 0 RM
87 (at) WS
33 0 RM
144 (the) WS
33 0 RM
183 (root) WS
33 0 RM
84 (of) WS
33 0 RM
144 (the) WS
33 0 RM
210 (tree,) WS
33 0 RM
531 (decompose) WS
33 0 RM
57 (it) WS
33 0 RM
171 (into) WS
33 0 RM
57 (a) W1
33 0 RM
261 (forest) WS
33 0 RM
84 (of) WS
33 0 RM
102 (16) WS
33 0 RM
234 (trees) WS
33 0 RM
198 (\(see) WS
33 0 RM
201 (Z.1\).) WS
66 0 RM
252 (Make) WS
33 0 RM
144 (the) WS
33 0 RM
267 (newly) WS
900 993 M
18 33 4422 (created nodes the roots of 16 new trees, and attach the children of the original root node to the) BWS
900 870 M
16 33 3654 (proper roots of the 16 new trees, such that each new tree is a valid prefix tree.) BWS
720 528 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F2 sF
720 363 M
2 39 1086 (September 12, 1991) BWS
5457 363 M
63 (4) W1
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showpage
%%Page: 5 5
SS
F1 sF
720 7524 M
2 39 1518 (Additional IDRP Comments) BWS
4755 7524 M
765 (X3S3.3/91-272) WS
720 7212 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F0 sF
720 6858 M
2 51 234 ( 2. If) BWS
33 0 RM
57 (a) W1
33 0 RM
183 (root) WS
33 0 RM
84 (of) WS
33 0 RM
57 (a) W1
33 0 RM
189 (new) WS
33 0 RM
183 (tree) WS
33 0 RM
165 (has) WS
33 0 RM
192 (only) WS
33 0 RM
171 (one) WS
33 0 RM
219 (child) WS
33 0 RM
255 (node,) WS
33 0 RM
171 (and) WS
33 0 RM
174 (that) WS
33 0 RM
228 (node) WS
S0 sF
30 (\242) WS
F0 sF
51 (s) W1
33 0 RM
258 (prefix) WS
33 0 RM
78 (is) WS
33 0 RM
144 (the) WS
33 0 RM
252 (same) WS
33 0 RM
108 (as) WS
33 0 RM
144 (the) WS
33 0 RM
258 (prefix) WS
33 0 RM
84 (of) WS
900 6735 M
18 33 4425 (its parent, remove the root \(parent\) node from the tree, and make the child node the root of the) BWS
900 6612 M
210 (tree.) WS
720 6426 M
2 51 261 ( 3. If,) BWS
33 0 RM
210 (after) WS
33 0 RM
390 (applying) WS
33 0 RM
246 (steps) WS
S0 sF
33 0 RM
135 (\2621\262) WS
F0 sF
33 0 RM
171 (and) WS
S0 sF
33 0 RM
162 (\2622\262,) WS
F0 sF
33 0 RM
240 (there) WS
33 0 RM
153 (are) WS
33 0 RM
234 (trees) WS
33 0 RM
84 (in) WS
33 0 RM
144 (the) WS
33 0 RM
261 (forest) WS
33 0 RM
174 (that) WS
33 0 RM
222 (have) WS
33 0 RM
240 (more) WS
33 0 RM
201 (than) WS
33 0 RM
51 (1) W1
33 0 RM
219 (child) WS
33 0 RM
255 (node,) WS
900 6303 M
8 33 2139 (arbitrarily select one of them and apply steps ) BWS
S0 sF
1 33 168 (\2621\262 ) BWS
F0 sF
1 33 204 (and ) BWS
S0 sF
1 33 168 (\2622\262 ) BWS
F0 sF
1 33 204 (to it.) BWS
720 6117 M
2 51 648 ( 4. Terminate) BWS
33 0 RM
435 (recursion) WS
33 0 RM
246 (when) WS
33 0 RM
144 (the) WS
33 0 RM
261 (forest) WS
33 0 RM
387 (contains) WS
33 0 RM
192 (only) WS
33 0 RM
363 (isolated) WS
33 0 RM
306 (nodes.) WS
720 5871 M
16 33 4734 (This procedure is similar to a depth-first search exploration of the tree, since only nodes with children) BWS
720 5748 M
14 33 4776 (are decomposed, while leaf nodes are not. Repeated application of the procedure replaces the original) BWS
720 5625 M
2 33 696 (prefix tree with) BWS
66 0 RM
16 33 3726 (a forest of isolated nodes. That is, it provides a means to replace a set of routes) BWS
720 5502 M
13 33 4017 (having nested NSAP address prefixes by a set of routes having disjoint NSAP prefixes.) BWS
66 0 RM
1 33 570 (Even though) BWS
720 5379 M
14 33 4329 (the disjoint prefixes may have different lengths, no two prefixes are nested within each other.) BWS
720 5133 M
9 33 2082 (To select a next hop for a particular NPDU, it) BWS
9 33 2427 (is sufficient to find a route whose prefix matches the) BWS
720 5010 M
13 33 4626 (destination NSAP address of the NPDU. Because the procedure above produces routes with disjoint) BWS
720 4887 M
14 33 4221 (NSAP address prefixes, at most one prefix can match the destination address of the NPDU.) BWS
66 0 RM
1 33 426 (Thus, the) BWS
720 4764 M
15 33 4593 (semantics achieved as a result of these procedures is equivalent to the semantics of longest prefix) BWS
720 4641 M
450 (matching.) WS
720 4386 M
6 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F9 sF
720 4245 M
204 (Z.4) WS
108 0 RM
7 54 4074 (Application of Construction and Dismantling of Prefix Trees) BWS
F0 sF
720 3969 M
15 33 4572 (It is possible to have routes with nested NSAP address prefixes in the following information bases:) BWS
S6 sF
786 3792 M
36 (\267) WS
F0 sF
78 0 RM
0 -9 RM
11 33 3312 (in Adj-RIBs-In \(either within a single RIB, across multiple RIBs, or both\)) BWS
S6 sF
786 3669 M
36 (\267) WS
F0 sF
78 0 RM
0 -9 RM
5 33 1599 (in Loc-RIBs or the associated FIBs) BWS
S6 sF
786 3546 M
36 (\267) WS
F0 sF
78 0 RM
0 -9 RM
1 33 714 (in Adj-RIBs-Out) BWS
720 3351 M
7 33 2130 (These cases can be handled as shown below.) BWS
F10 sF
720 3051 M
285 (Z.4.1) WS
96 0 RM
3 48 1818 (Nested Prefixes in Adj-RIBs-In) BWS
F0 sF
720 2805 M
17 33 4740 (For each Adj-RIB-In, apply the procedures of Z.3 in order to replace any nested NSAP prefixes with an) BWS
720 2682 M
4 33 1557 (equivalent set of disjoint prefixes.) BWS
66 0 RM
12 33 3009 (If a tree whose root has only one child is encountered during the) BWS
720 2559 M
17 33 4701 (dismantling phase, and the NSAP address prefix of that child is the same as the NSAP address prefix) BWS
720 2436 M
5 33 969 (of the root \(see step ) BWS
S0 sF
1 33 168 (\2622\262 ) BWS
F0 sF
15 33 3507 (of Z.3\), and the route associated with the child node can not be used by the) BWS
720 2313 M
19 33 4461 (local BIS \(this may happen if the local RDI or one of the RDCIs is already in the RD_PATH\), then) BWS
720 2190 M
9 33 2217 (replace this tree by a forest of trees, as follows:) BWS
66 0 RM
10 33 2490 (remove both the root and its only child, and make the) BWS
720 2067 M
12 33 3228 (children of that child \(grandchildren of the root\) the roots of the trees.) BWS
66 0 RM
5 33 1443 (At the completion of this phase) BWS
720 1944 M
13 33 4008 (for a single Adj-RIB-In, that Adj-RIB-In has no routes with nested NSAP address prefix.) BWS
720 1698 M
2 33 954 (After the procedures) BWS
66 0 RM
14 33 3648 (of Z.3 are applied individually to all of the Adj-RIB-Ins, they are then applied to) BWS
720 1575 M
21 33 4797 (all the routes with nested NRLI that are present in all Adj-RIB-Ins. As a result of this, a BIS will have no) BWS
720 1452 M
15 33 4743 (routes with nested NSAP address prefixes, and the decision process can be applied to each individual) BWS
720 1329 M
267 (route.) WS
66 0 RM
16 33 4296 (The decision process may, as a matter of local routing policy, take into account the length of) BWS
720 1206 M
5 33 1410 (the prefix of the original route.) BWS
720 528 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F2 sF
720 363 M
2 39 1086 (September 12, 1991) BWS
5457 363 M
63 (5) W1
setup R
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%%Page: 6 6
SS
F1 sF
720 7524 M
2 39 1518 (Additional IDRP Comments) BWS
4755 7524 M
765 (X3S3.3/91-272) WS
720 7212 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F10 sF
720 6816 M
285 (Z.4.2) WS
96 0 RM
5 48 2259 (Nested Prefixes in Loc-RIBs and FIBs) BWS
F0 sF
720 6570 M
14 33 4719 (Once decision process is completed, the selected routes can be installed in Loc-RIB/FIB. To conserve) BWS
720 6447 M
17 33 4485 (space it may be desirable to compose the routes that are about to be installed in Loc-RIB/FIB by) BWS
720 6324 M
14 33 4644 (applying the route composition procedure. If such procedure is performed, then the Loc-RIB and FIB) BWS
720 6201 M
9 33 2721 (are going to have routes with nested NSAP address prefix.) BWS
F10 sF
720 5901 M
285 (Z.4.3) WS
96 0 RM
3 48 1914 (Nested Prefixes in Adj-RIBs-Out) BWS
F0 sF
720 5655 M
19 33 4797 (If either all of the routes in the Loc-RIB whose NSAP address prefixes are nested, or none of the routes) BWS
720 5532 M
15 33 4200 (whose in the Loc-RIB whose NSAP address prefix are nested can be placed in a particular) BWS
720 5409 M
6 33 2373 (Adj-RIB-Out, then no further actions are necessary.) BWS
720 5163 M
17 33 4605 (Otherwise, the procedure of Z.3 should be applied to the sets of routes that have nested NSAP pre-) BWS
720 5040 M
240 (fixes.) WS
66 0 RM
3 33 432 (If in step ) BWS
S0 sF
1 33 195 (\2622\262, ) BWS
F0 sF
14 33 3684 (the sole child of the root can not be installed in the particular Adj-RIB-Out, then) BWS
720 4917 M
20 33 4731 (remove both the root and its child, and replace the tree with a forest of trees, where the root nodes of) BWS
720 4794 M
11 33 3408 (these trees are composed of the grandchildren nodes of the original root.) BWS
66 0 RM
3 33 1170 (After applying this proce-) BWS
720 4671 M
16 33 4779 (dure, all the routes that can not be installed in that particular Adj-RIB-Out are removed. The cardinality) BWS
720 4548 M
16 33 4698 (of the remaining set of routes can be reduced by applying the route composition procedure \(see Z.2\).) BWS
720 4425 M
17 33 4743 (This can reduce the amount of information to be exchanged between the adjacent BISs, as well as the) BWS
720 4302 M
6 33 1887 (amount to be stored in the Adj-RIBs-Out.) BWS
720 4047 M
6 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F9 sF
720 3906 M
204 (Z.5) WS
108 0 RM
6 54 3861 (Aggregating Routes with Nested NSAP Address Prefixes) BWS
F0 sF
720 3630 M
17 33 4401 (If a BIS desires to aggregate a set of routes \(either before installing them in Loc-RIB, or before) BWS
720 3507 M
15 33 4749 (installing them in Adj-RIB-Out\), then it must check whether any of these routes were originally present) BWS
720 3384 M
19 33 4608 (in any of the Adj-RIB-Ins, or were created as a result of applying the procedures of Z.3. In the latter) BWS
720 3261 M
15 33 4494 (case, it is necessary to find the original route \(from one of the Adj-RIBs-In\) whose decomposition) BWS
720 3138 M
14 33 4509 (created the route to be aggregated. Then, after constructing the path attributes of the aggregated) BWS
720 3015 M
16 33 4749 (route, path attributes of all other routes that were created from the decomposition of the original route) BWS
720 2892 M
10 33 3141 (should be replaced with the path attributes of the aggregated route.) BWS
720 2637 M
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F9 sF
720 2496 M
204 (Z.6) WS
108 0 RM
8 54 4362 (Routes with Identical Path Attributes and Nested NSAP prefixes) BWS
F0 sF
720 2220 M
16 33 4653 (If a BIS receives from an adjacent BIS an UPDATE BISPDU that contains an elementary route whose) BWS
720 2097 M
16 33 4731 (NSAP address prefix is nested within a route previously advertised by the same adjacent BIS, and the) BWS
720 1974 M
16 33 4512 (path attributes of both routes are identical, then the newly advertised route shall be placed in the) BWS
720 1851 M
8 33 2982 (appropriate Adj-RIB-In, and no further actions will be necessary.) BWS
720 528 M
18 LW
cP /sY xdef /sX xdef
4800 0 rL
sX sY M
F2 sF
720 363 M
2 39 1086 (September 12, 1991) BWS
5457 363 M
63 (6) W1
setup R
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end   %End the ibmafpds dictionary
%%Trailer