APPN Configurations: Recommendations & Limitations. Johnathan Harter z/os CommServer Development

Transcription

1 Configurations: Recommendations & Limitations Johnathan Harter z/os CommServer Development 1

2 Agenda Node Types Central Directory Servers (CDServers) Connection Networks (VRNs) Session Services Extensions (SSE) Dependent LU Requesters/Servers (DLUR/DLUS) Branch Extenders (BEX) Extended Border Nodes (EBN) 2

3 Node Types Defines Only Two Types Of Nodes End Nodes (s) - Session endpoints only (no intermediate routing) CP-CP sessions with one adjacent NN at a time (Network Node Server or NNS) Network Nodes (NNs) - Session endpoints or intermediate nodes CP-CP sessions with any adjacent NN and served s Specialized End Nodes (VTAM Only) Migration Data Hosts (MDHs) - Support both and Subarea (CP and CDRM) Specialized Network Nodes (Most Are VTAM Only) Composite Network Nodes (CNNs) - Activates and/or owns NCPs Interchange Nodes (ICNs) - Support both and Subarea (CP and CDRM) Central Directory Servers (CDServer) - version of "CMC" (resource directory) Dependent LU Servers (DLUSs) - version of "CMC" (resource ownership) Extended Border Nodes (EBNs) - version of SNI Gateway Virtual Routing Nodes (VRNs) - Used to represent Connection Networks NNs That Can Act Like s Branch Extenders (BEXs) Peripheral and Extended Border Nodes (PBNs and EBNs) 3

4 Node Type Examples V R N CNN, ICN Subarea MDH CDS, EBN Subarea BEX EBN 4

5 Node Type Recommendations Define As Many Nodes As s As Possible s do not participate in "network-wide" functions Maintaining network topology Searching for resources (LUs) s can dedicate more resources (storage, CPU) to production work Define As Few NNs As Possible Network topology database is smaller Easier to optimize session routes Network search overhead is reduced Use Specialized NNs As Needed CNNs are needed as long as there are NCPs ICNs are needed if sessions span /Subarea boundaries CDServers are recommended for all but the smallest networks DLUSs are used when dependent LUs are moved from NCPs to DLURs BEXs are used to minimize network topology in Branch Office environments EBNs are needed for multi-subnetwork connectivity VRNs provide meshed connectivity between nodes without meshed defintions 5

6 Interchange Node HPR Limitations Legend ER/VR Subarea (FID4) (FID2) (FID2) HPR Pure Session One RTP pipe can be used for the entire path ICN Session RTP pipe out of ICN is always only one-hop Remainder of session path can use a single RTP pipe 6

7 Agenda Node Types Central Directory Servers (CDServers) Connection Networks (VRNs) Session Services Extensions (SSE) Dependent LU Requesters/Servers (DLUR/DLUS) Branch Extenders (BEX) Extended Border Nodes (EBN) 7

8 Central Directory Servers FIND(LUB) NN2 L LUA A NN1 CDS NN4 LUB B NN3 Used To Minimize Broadcast Searching Network Topology DB identifies which NNs are CDServers Non-CDServer NNs query a CDServer instead of broadcasting CDServers query other CDServers before broadcasting Other Searches That Can Also Occur Broadcast Search (if no CDServers have current information) Serial ICN Search of attached subarea networks Too Many CDServers Can Mean Too Much Searching 8

9 Central Directory Server Recommendations FIND(LUB) NN2 L LUA A NN1 CDS NN4 LUB B NN3 Choose Number Of CDServers Based On Network Size 3 or fewer NNs - No CDServers are needed 4 or more NNs - At least 1 CDServer is recommended Second CDServer is also okay (in case of failure) 6 or more NNs - At least 2 CDServers are recommended More than 4 CDServers is probably too many (not recommended) 9

10 Central Directory Server Placement A NN1 CDS CPSVCMG Weight = 60 NN3 C CPSVCMG Weight = 30 CPSVCMG Weight = 30 B NN2 CPSVCMG Weight = 60 NN4 CDS D Choose CDServers Based On Network Geography (Assumes no subnetwork boundaries) Define a CDServer in each physical data center (location) Define links and CPSVCMG COS to prefer local CDServer Most NNs choose a CDServer based on weight of Locate path Define links between local NNs to resolve to a lower weight Define links between remote NNs to resolve to a higher weight Non-CDServer NNs will choose local CDServer Remote CDServers are used as backup (assuming a path exists) Data Center 1 Data Center 2 10

11 Agenda Node Types Central Directory Servers (CDServers) Connection Networks (VRNs) Session Services Extensions (SSE) Dependent LU Requesters/Servers (DLUR/DLUS) Branch Extenders (BEX) Extended Border Nodes (EBN) 11

12 Connection Networks (Virtual Routing Nodes) Why Are VRNs Important? To minimze link definitions between nodes that share a common transport Token Ring, X25, ATM, EE To simplify adding new nodes b Without VRNs Links must be defined between each pair of nodes for optimal routing 4 nodes, 12 links (4x3) 5 nodes, 20 links (5x4) 'n' nodes, n*(n-1) links NNa d b c With VRNs Links are defined to CP-CP partners and to Virtual Routing Node only 4 nodes, 8 links (4x2) 5 nodes, 10 links (5x2) 'n' nodes, nx2 links Direct links between other nodes are created dynamically NNa VRN d c 12

13 Interchange Node HPR Limitations For VRNs Legend ER/VR Subarea (FID4) (FID2) (FID2) HPR VRN Pure Session One RTP pipe can be used for the entire path ICN Session RTP pipe out of ICN is always only one-hop Remainder of session path can use a single RTP pipe 13

14 Connection Network Recommendations Use Connection Networks Whenever Possible To: Minimize link definitions Achieve optimal session paths Simplify adding new nodes On NNs, s and MDHs: Any type of Connection Network can be defined Independent of z/os CS release On Interchange Nodes (ICNs): Any type of Connection Network can be defined on all releases that have not yet reached End Of Service If you are still running pre-v1r4 z/os CS nodes as Interchange Nodes Define ISR-capable Connection Networks only! (TR & X25) Predefine HPR-only (EE) links from ICNs to all adjacent nodes (instead of defining HPR-only Connection Networks on ICNs) 14

15 Agenda Node Types Central Directory Servers (CDServers) Connection Networks (VRNs) Session Services Extensions (SSE) Dependent LU Requesters/Servers (DLUR/DLUS) Branch Extenders (BEX) Extended Border Nodes (EBN) 15

16 Session Services Extensions Was Originally Designed For LU 6.2 Sessions Only All sessions were initiated by the Primary LU (PLU-Initiated) No SLU-Initiated sessions (REQSESS, LOGAPPL or SLU logons) No Third-party Initiated sessions (CLSDST PASS) All LUs were multi-session capable. No requirement for: Session queuing (SIMLOGON Q) Printer Sharing (RELREQ) Session Services Extensions (SSE) Created by Architecture and VTAM for VTAM V4R1 (first release) Optional "tower" on top of base or NN function Extended the Architecture to support existing subarea functions Provided seamless migration path from subarea to networking No impact to existing applications or external customers Unsupported by most products Co-exists very well with non-sse capable nodes 16

17 Session Services Extensions Exploitation L AS/400 NN2 VTAM A VTAM NN1 VTAM NN4 VTAM B AS/400 NN3 SSE Exploitation Requirements Owning CP and NNS of both the OLU and DLU must support SSE Intermediate NNs do not have to support SSE On Locate path or BIND (session) path Sessions between A, NN1, NN4, B can use SSE 17

18 Agenda Node Types Central Directory Servers (CDServers) Connection Networks (VRNs) Session Services Extensions (SSE) Dependent LU Requesters/Servers (DLUR/DLUS) Branch Extenders (BEX) Extended Border Nodes (EBN) 18

19 Dependent LU Requester/Server (With SSE) Supports Dependent LUs Without DLUR! Dependent LUs attach as usual Must appear adjacent to VTAM/NCP Session path must include owning VTAM Possibly through owned NCPs only HPR is only possible to VTAM (NCP cannot be an RTP endppoint) DLUR Extends This Support To: Remove VTAM/NCP adjacency requirement DLURs can be located in remote sites More fully exploit HPR RTPs can extend out to the DLUR Route traffic more intelligently Session paths need not include the owning VTAM (but owning VTAM maintains session awareness) DLUS DLUR Control flows Session path Boundary Function Control flows Session path Boundary Function 19

20 Dependent LU Requester Placement DLUS DLUS DLUR Cisco SNASw CS/NT DLURs CS/Linux DLUR In Gateway No hit to downstream devices Fewer control sessions and RTPs More resources used by gateway Gateway is single point of failure DLUR In End Stations Best performance and availability HPR routes around failing gateway Fewer resources used by gateway More control sessions and RTPs 20

21 Agenda Node Types Central Directory Servers (CDServers) Connection Networks (VRNs) Session Services Extensions (SSE) Dependent LU Requesters/Servers (DLUR/DLUS) Branch Extenders (BEX) Extended Border Nodes (EBN) 21

22 Branch Extenders Data Center Data Center NN Branch... Branch NN BEX Branch... BEX Branch NN Common Configuration Central data center supporting many remote branches Topology updates and searches can overwhelm branch network nodes Branch Extender Objectives Reduce TDUs & searches to branches Eliminate trial-and-error searching of branches for branch resources Intended for single-enterprise networks How BEX Node Works Acts like to data center (uplinks) Acts like NN to branch s (downlinks) NNs are not allowed below a BEX! L nodes are allowed below a BEX Resource Registration is forwarded into data center by BEX More efficient than EBN searching HPR to BEX and downstream s DLUR on BEX (but not below) 22

23 Cascaded and Parallel Branch Extenders BEX BEX Branch NN NN BEX or NN? Branch BEX NN Cascaded BEX Nodes Resource Registration requests are forwarded through each BEX node Can be used in "regional data center" configurations to reduce the number of DLURs Parallel BEX Nodes Divide ownership and backup, or Use duplicate TICs for high availability What about BEX-to-BEX link? Predefined link does not work If needed, define branch VRN instead 23

24 Branch Extender Limitations SSE Suppport BEX Is Not Required To Support SSE SSE is not supported below a BEX node! Downstream VTAMs are not recommended Limited to LU 6.2 (PLU-Init) Sessions Traffic can overload BEX node(s) BEX NN DLUR Support BEX nodes can be DLURs DLURs are not supported below a BEX node! If cascasded BEX nodes are used, highest level BEX node must be the DLUR Dependent LU passthrough function may be needed on lower level BEX nodes BEX Branch NN Connection Network (VRN) Support VRNs can be exploited within the branch VRNs cannot be used to route around a BEX BEX node acting as NNS will always be on the path of sessions into the data center 24

25 Agenda Node Types Central Directory Servers (CDServers) Connection Networks (VRNs) Session Services Extensions (SSE) Dependent LU Requesters/Servers (DLUR/DLUS) Branch Extenders (BEX) Extended Border Nodes (EBN) 25

26 Extended Border Nodes NN NN EBN EBN EBN NETA NETB NETC Peripheral Boundary Extended Boundary EBNs Provide "Multi-Subnetwork Connectivity" (" SNI") Optional "tower" on top of "base NN function plus SSE" Restricts Topology flows over subnetwork boundaries, but... Allows searches ( Locates) and sessions to cross subnetwork boundaries (user-controlled, dynamic, or combination of both) EBNs Support Two Types Of Subnetwork Boundary Peripheral boundary (EBN on only one side of boundary) EBN acts like an to adjacent non-native NN Not the same as Peripheral Border Node (AS/400 version) Extended boundary (EBN on both sides of boundary; recommended) 26

27 Peripheral Boundary Limitations EBN NN NN EBN EBN EBN Peripheral Boundary Peripheral Boundary Extended Boundary Peripheral Boundary Must Be First And/Or Last Network Boundaries On The Session Path All intermediate subnetwork boundaries on session path must be Extended If used with two or more subnetwork boundaries: EBNs must be on the "inside" of the peripheral boundaries Peripheral Boundary Must Be The ONLY Connection To The Adjacent Subnetwork (Direct or Indirect!) No other Extended or Peripheral subnetwork boundaries No Subarea or SNI connections No L connections Parallel links (between the same two nodes) are allowed 27

28 Peripheral Boundary Examples Does this configuration look OK? NO! BN3 has TWO links into the same peripheral network Can cause routing loops that are not detectable NN7 NETC BN6 NETA 9 BN1 BN3 NN2 NN5 BN4 NETA 8 NETB How about this configuration? NO AGAIN! Although BN3 does not have two links to the same peripheral network, there is still more than one path into the subnetworks containing NN2 and NN5 The same undetectable routing loops can occur NN7 NETC BN6 NETA 9 BN1 BN3 NN2 NN5 NETB NETB BN4 NETA 8 28

29 Extended Border Nodes And SSE OLU NN NN EBN EBN EBN NN DLU NETA NETB NETC CP(OLU) NNS(OLU) NNS(DLU) NNS(OLU) NNS(DLU) NNS(OLU) NNS(DLU) CP(DLU) SSE Are Supported Across Subnetwork Boundaries Which nodes must be SSE Capable? Owning CP and NNS of both the OLU and DLU in each subnetwork Intermediate NNs in each subnetwork do not have to support SSE All Extended Boundaries provide full SSE support SSE support is a prerequisite for EBN functions Not all Peripheral Boundaries provide SSE support Depends on the capabilities of the non-native NN 29

30 Extended Border Nodes And DLUR/DLUS NETA 9 BN1 DLUS BN3 NN7 PLU1 NETC BN6 BN4 NETA 8 PLU2 BN2 DLUR1 NETB NN5 DLUR2 NETB DLUR, DLUS And PLU Can Each Be In Different Subnetworks What types of boundaries are allowed? All Three "Paths" Must Be Considered: DLUS-To-DLUR: CPSVRMGR session path One Peripheral Boundary is allowed: Border Node must be on DLUS-side DLUS-To-PLU: Locate path Extended Boundaries only (even if SSE is supported by adjacent NN) PLU-To-DLUR: End-user session path One Peripheral Boundary is allowed: Border Node must be on PLU-side 30

31 Global Connection Networks (GVRNs) NETA 9 BN1 BN3 NN7 NETC VRN BN6 GVRN BN4 NETA 8 BN2 NETB NN5 NETB Local VRNs (TR, X25, ATM and EE): Connection Network (VRN) can only be used natively (within a subnetwork) Cross-subnetwork sessions must traverse the EBNs on Locate path Global VRNs (EE only): Connection Network (VRN) can be used across subnetwork boundaries Allows cross-subnetwork sessions to use a direct (dynamically created) link Can be used to eliminate EBNs as a potential performance bottle-neck 31

32 Global Connection Network Limitations NETA 9 BN1 BN3 NN7 NETC VRN BN6 GVRN BN4 NETA 8 BN2 NETB NN5 NETB Global Connection Networks: Require "Extended Boundaries" along the entire Locate path Are only used between OLU and DLU subnetworks Not used to or from intermediate subnetworks on Locate path Are not used when the OLU or DLU are "in subarea". However... Once RTPs are established, they can be path switched over GVRNs Can be exploited by Branch Extenders, but not by downstream nodes Multiple EE (G)VRNs, IPv6 (G)VRNs and Firewalls are supported 32

33 For More Information... URL Content IBM eserver zseries Mainframe Servers Networking: IBM zseries Servers IBM Enterprise Servers: Networking Technologies Communications Server product overview z/os Communications Server Communications Server for Linux on zseries Communication Controller for Linux on zseries Communications Server products - white papers, product documentation, etc. ITSO redbooks Communications Server technical Support Technical support documentation (techdocs, flashes, presentations, white papers, etc.) Request For Comments (RFC) IBM Education Assistant 33