LISP RLOCのPriorityとWeight

今回はLISPのRLOCのPriorityとWeightと呼ばれるパラメータについて説明します。

概要

RLOCのPriorityとWeight

以下の様に特定のEID-Prefixに対して、複数のRLOC経由で到達可能な場合、ITRがどのような基準に基づいて、転送先のRLOCを決定するか疑問が生じると思います。

この際に使用するパラメータがRLOCのPriorityとWeightであり、Priorityが最小のRLOCに対してITRはパケットを転送します。

もし、Priorityが同じ場合は、Weightの比率を基に、パケットをバランシングして転送します。

ITRがEID-Prefixに対応する複数のRLOCを学習できるように、各ETRでは自身のMapping Databaseに同じ拠点に属する他のETRのRLOCとEID-Prefixのマッピング情報を登録しておく必要があります。
これにより、MSからMap Requestメッセージを受信した際に、同じ拠点の全ETRのRLOCをITRに返信できます。

検証の基本設定

基本設定の内容

R1をMR/MS、R2とR3をxTRとして動作させます。
R2はEID-Prefixが10.1.1.0/24、RLOCが172.16.1.2のマッピング情報をR1に登録します。
R3はEID-Prefixが10.2.2.0/24、RLOCが172.16.3.3と172.16.4.3のマッピング情報をR1に登録します。

そして、R3のRLOCのPriorityやWeightを変更して、動作を確認します。

基本設定

R1の設定


interface GigabitEthernet2
 ip address 172.16.1.1 255.255.255.0
!
router lisp
 service ipv4
  map-server
  map-resolver
  exit-service-ipv4
 !
 site Site_1
  authentication-key Zaq12wsx!@
  eid-record 10.1.1.0/24
  eid-record 10.2.2.0/24
  exit-site
 !
 exit-router-lisp
!
ip route 0.0.0.0 0.0.0.0 172.16.1.6

R2の設定


interface GigabitEthernet2
 ip address 172.16.2.2 255.255.255.0
!
interface GigabitEthernet3
 ip address 10.1.1.2 255.255.255.0
!
router lisp
 service ipv4
  itr map-resolver 172.16.1.1
  itr
  etr map-server 172.16.1.1 key Zaq12wsx!@
  etr
  exit-service-ipv4
 !
 instance-id 0
  service ipv4
   eid-table default
   database-mapping 10.1.1.0/24 172.16.2.2 priority 1 weight 50
   exit-service-ipv4
  !
  exit-instance-id
 !
 exit-router-lisp
!
ip route 0.0.0.0 0.0.0.0 172.16.2.6

R3の設定


interface GigabitEthernet2
 ip address 172.16.3.3 255.255.255.0
!
interface GigabitEthernet3
 ip address 172.16.4.3 255.255.255.0
!
interface GigabitEthernet4
 ip address 10.2.2.3 255.255.255.0
!
router lisp
 service ipv4
  itr map-resolver 172.16.1.1
  itr
  etr map-server 172.16.1.1 key Zaq12wsx!@
  etr
  exit-service-ipv4
 !
 instance-id 0
  service ipv4
   eid-table default
   database-mapping 10.2.2.0/24 172.16.3.3 priority 10 weight 50
   database-mapping 10.2.2.0/24 172.16.4.3 priority 10 weight 50
   exit-service-ipv4
  !
  exit-instance-id
 !
 exit-router-lisp
!
ip route 0.0.0.0 0.0.0.0 172.16.3.6
ip route 0.0.0.0 0.0.0.0 172.16.4.6

R4の設定


interface GigabitEthernet2
 ip address 10.1.1.4 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 10.1.1.2

R5の設定


interface GigabitEthernet2
 ip address 10.2.2.5 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 10.2.2.3

R6の設定


interface GigabitEthernet2
 ip address 172.16.1.6 255.255.255.0
!
interface GigabitEthernet3
 ip address 172.16.2.6 255.255.255.0
!
interface GigabitEthernet4
 ip address 172.16.3.6 255.255.255.0
!
interface GigabitEthernet5
 ip address 172.16.4.6 255.255.255.0

設定内容と状態の確認(PriorityとWeightが等しいケース)

検証内容

R3の2個のRLOCのPriorityとWeightが等しい場合の動作を確認します。

ETRであるR3の設定と状態確認

R3では、EID-Prefixを2個のRLOCにマッピングさせるために、database-mappingコマンドを2回設定します。Priorityには10、Weightには50を設定します。


router lisp
 instance-id 0
  service ipv4
   database-mapping 10.2.2.0/24 172.16.3.3 priority 10 weight 50
   database-mapping 10.2.2.0/24 172.16.4.3 priority 10 weight 50
   exit-service-ipv4
  !
  exit-instance-id
 !
 exit-router-lisp

R3のMapping Databaseでは、EID-Prefixの10.2.2.0/24に、RLOCとして172.16.3.3と172.16.4.3が登録されていることが確認できます。また、PriorityをWeightが等しいことが確認できます。


R3#show ip lisp database
LISP ETR IPv4 Mapping Database for EID-table default (IID 0), LSBs: 0x3
Entries total 1, no-route 0, inactive 0

10.2.2.0/24
  Uptime: 19:55:23, Last-change: 19:55:23
  Domain-ID: unset
  Locator     Pri/Wgt  Source     State
  172.16.3.3   10/50   cfg-addr   site-self, reachable
  172.16.4.3   10/50   cfg-addr   site-self, reachable

MR/MSであるR1の状態確認

EID-Prefixである10.2.2.0/24に172.16.3.3と172.16.4.3の2個のRLOCが関連付けられていることが確認できます。
また、PriorityとWeightは等しいことが確認できます。


R1#show lisp site detail
LISP Site Registration Information

Site name: Site_1
Allowed configured locators: any
Allowed EID-prefixes:

  EID-prefix: 10.1.1.0/24
    First registered:     19:55:06
    Last registered:      19:55:02
    Routing table tag:    0
    Origin:               Configuration
    Merge active:         No
    Proxy reply:          No
    Skip Publication:     No
    Force Withdraw:       No
    TTL:                  1d00h
    State:                complete
    Registration errors:
      Authentication failures:   0
      Allowed locators mismatch: 0
    ETR 172.16.2.2:28538, last registered 19:55:02, no proxy-reply, map-notify
                          TTL 1d00h, no merge, hash-function sha1, nonce 0xE0C350C9-0x90A7389C
                          state complete, no security-capability
                          xTR-ID 0xF180E005-0x7DEB7B41-0x6FFC3231-0xCD92F0F5
                          site-ID unspecified
                          Domain-ID unspecified
                          Multihoming-ID unspecified
                          sourced by reliable transport
      Locator     Local  State      Pri/Wgt  Scope
      172.16.2.2  yes    up           1/50   IPv4 none

  EID-prefix: 10.2.2.0/24
    First registered:     19:54:40
    Last registered:      19:54:36
    Routing table tag:    0
    Origin:               Configuration
    Merge active:         No
    Proxy reply:          No
    Skip Publication:     No
    Force Withdraw:       No
    TTL:                  1d00h
    State:                complete
    Registration errors:
      Authentication failures:   0
      Allowed locators mismatch: 0
    ETR 172.16.4.3:39547, last registered 19:54:36, no proxy-reply, map-notify
                          TTL 1d00h, no merge, hash-function sha1, nonce 0x9B83FB8F-0x889A67B2
                          state complete, no security-capability
                          xTR-ID 0xF3560DA6-0x58A122AE-0x156B8B9A-0xD124C412
                          site-ID unspecified
                          Domain-ID unspecified
                          Multihoming-ID unspecified
                          sourced by reliable transport
      Locator     Local  State      Pri/Wgt  Scope
      172.16.3.3  yes    up          10/50   IPv4 none
      172.16.4.3  yes    up          10/50   IPv4 none

ITRであるR2の状態確認

R2はEID-Prefixの10.2.2.0/24のRLOCとして172.16.3.3と172.16.4.3を学習していることが確認できます。
また、PriorityとWeightが等しいことが確認できます。


R2#show ip lisp map-cache
LISP IPv4 Mapping Cache for EID-table default (IID 0), 2 entries

0.0.0.0/0, uptime: 00:00:43, expires: 00:00:16, via static-send-map-request
  Negative cache entry, action: send-map-request
10.2.2.0/24, uptime: 00:01:47, expires: 23:58:13, via map-reply, complete
  Locator     Uptime    State  Pri/Wgt     Encap-IID
  172.16.3.3  00:01:47  up      10/50        -
  172.16.4.3  00:01:47  up      10/50        -

今回、PriorityとWeightが等しいため、R2は10.2.2.0/24宛のパケットを、172.16.3.3.と172.16.4.3に1:1の割合でバランシングして転送します。
どのような比率でバランシングして転送するかはshow ip lisp forwarding eid remote detailコマンドで確認できます。
16個のhash bucketsが172.16.3.3と172.16.4.3に1:1の比率で割り当てられていることが確認できます。


R2#show ip lisp forwarding eid remote detail
Prefix                 Fwd action  Locator status bits   encap_iid
0.0.0.0/0              signal      0x00000000            N/A
  packets/bytes       1/114
  path list 7FC0E7721868, 3 locks, per-destination, flags 0x49 [shble, rif, hwcn]
    ifnums:
      LISP0(43)
    1 path
      path 7FC0E77B4190, share 1/1, type attached prefix, for IPv4
        attached to LISP0, glean for LISP0
    1 output chain
      chain[0]: glean for LISP0
10.2.2.0/24            encap       0x00000003            N/A
  packets/bytes       4/456
  path list 7FC0E77217C0, 3 locks, per-destination, flags 0x49 [shble, rif, hwcn]
    ifnums:
      LISP0(43): 172.16.3.3, 172.16.4.3
    2 paths
      path 7FC0E77B4740, share 50/50, type attached nexthop, for IPv4
        nexthop 172.16.3.3 LISP0, IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
      path 7FC0E77B4260, share 50/50, type attached nexthop, for IPv4
        nexthop 172.16.4.3 LISP0, IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
    1 output chain
      chain[0]: loadinfo 80007FC0DE66F1D0, per-session, 2 choices, flags 0003, 5 locks
                  flags [Per-session, for-rx-IPv4]
                  16 hash buckets
                    < 0 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 1 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 2 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 3 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 4 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 5 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 6 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 7 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 8 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 9 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <10 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <11 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <12 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <13 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <14 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <15 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                  Subblocks:
                    None

R2のCEFの10.2.2.0/24のネクストホップには172.16.3.3と172.16.4.3が登録されていることが確認できます。


R2#show ip cef 10.2.2.0/24 detail
10.2.2.0/24, epoch 2, flags [subtree context, check lisp eligibility, default route]
  SC owned,sourced: LISP remote EID - locator status bits 0x00000003
  LISP remote EID: 4 packets 456 bytes fwd action encap, cfg as EID space
  LISP source path list
    nexthop 172.16.3.3 LISP0
    nexthop 172.16.4.3 LISP0
  2 IPL sources [active source]
    Dependent covered prefix type inherit, cover 0.0.0.0/0
  recursive via 0.0.0.0/0
    recursive via 172.16.2.6
      attached to GigabitEthernet2

設定内容と状態の確認(Weightが異なるケース)

検証内容

R3のRLOCの172.16.3.3のWeightを50を100に変更した場合の動作を確認します。

ETRであるR3の設定と状態確認

RLOCの172.16.3.3のWeightを50から100に変更します。


router lisp
 instance-id 0
  service ipv4
   database-mapping 10.2.2.0/24 172.16.3.3 priority 10 weight 100
   database-mapping 10.2.2.0/24 172.16.4.3 priority 10 weight 50
   exit-service-ipv4
  !
  exit-instance-id
 !
 exit-router-lisp

R3のMapping Database内の172.16.3.3のWeightが50から100に変化したことが確認できます。


R3#show ip lisp database
LISP ETR IPv4 Mapping Database for EID-table default (IID 0), LSBs: 0x3
Entries total 1, no-route 0, inactive 0

10.2.2.0/24
  Uptime: 20:23:22, Last-change: 00:00:19
  Domain-ID: unset
  Locator     Pri/Wgt  Source     State
  172.16.3.3   10/100  cfg-addr   site-self, reachable
  172.16.4.3   10/50   cfg-addr   site-self, reachable

MR/MSであるR1の状態確認

R3がR1に登録した172.16.3.3のWeightが50から100に変化したことが確認できます。


R1#show lisp site detail
LISP Site Registration Information

Site name: Site_1
Allowed configured locators: any
Allowed EID-prefixes:

  EID-prefix: 10.1.1.0/24
    First registered:     20:23:59
    Last registered:      20:23:55
    Routing table tag:    0
    Origin:               Configuration
    Merge active:         No
    Proxy reply:          No
    Skip Publication:     No
    Force Withdraw:       No
    TTL:                  1d00h
    State:                complete
    Registration errors:
      Authentication failures:   0
      Allowed locators mismatch: 0
    ETR 172.16.2.2:28538, last registered 20:23:55, no proxy-reply, map-notify
                          TTL 1d00h, no merge, hash-function sha1, nonce 0xE0C350C9-0x90A7389C
                          state complete, no security-capability
                          xTR-ID 0xF180E005-0x7DEB7B41-0x6FFC3231-0xCD92F0F5
                          site-ID unspecified
                          Domain-ID unspecified
                          Multihoming-ID unspecified
                          sourced by reliable transport
      Locator     Local  State      Pri/Wgt  Scope
      172.16.2.2  yes    up           1/50   IPv4 none

  EID-prefix: 10.2.2.0/24
    First registered:     20:23:33
    Last registered:      00:00:31
    Routing table tag:    0
    Origin:               Configuration
    Merge active:         No
    Proxy reply:          No
    Skip Publication:     No
    Force Withdraw:       No
    TTL:                  1d00h
    State:                complete
    Registration errors:
      Authentication failures:   0
      Allowed locators mismatch: 0
    ETR 172.16.4.3:39547, last registered 00:00:31, no proxy-reply, map-notify
                          TTL 1d00h, no merge, hash-function sha1, nonce 0x9B83FB8F-0x889A67B2
                          state complete, no security-capability
                          xTR-ID 0xF3560DA6-0x58A122AE-0x156B8B9A-0xD124C412
                          site-ID unspecified
                          Domain-ID unspecified
                          Multihoming-ID unspecified
                          sourced by reliable transport
      Locator     Local  State      Pri/Wgt  Scope
      172.16.3.3  yes    up          10/100  IPv4 none
      172.16.4.3  yes    up          10/50   IPv4 none

ITRであるR2の状態確認

R2がR3から学習した172.16.3.3のWeightが50から100に変化したことが確認できます。


R2#show ip lisp map-cache
LISP ETR IPv4 Mapping Database for EID-table default (IID 0), LSBs: 0x3
Entries total 1, no-route 0, inactive 0

10.2.2.0/24
  Uptime: 20:23:22, Last-change: 00:00:19
  Domain-ID: unset
  Locator     Pri/Wgt  Source     State
  172.16.3.3   10/100  cfg-addr   site-self, reachable
  172.16.4.3   10/50   cfg-addr   site-self, reachable

16個のhash bucketsが172.16.3.3と172.16.4.3に2:1の比率で割り当てられていることが確認できます。


R2#show ip lisp forwarding eid remote detail
Prefix                 Fwd action  Locator status bits   encap_iid
0.0.0.0/0              signal      0x00000000            N/A
  packets/bytes       1/114
  path list 7FC0E7721868, 3 locks, per-destination, flags 0x49 [shble, rif, hwcn]
    ifnums:
      LISP0(43)
    1 path
      path 7FC0E77B4740, share 1/1, type attached prefix, for IPv4
        attached to LISP0, glean for LISP0
    1 output chain
      chain[0]: glean for LISP0
10.2.2.0/24            encap       0x00000003            N/A
  packets/bytes       4/456
  path list 7FC0E77217C0, 3 locks, per-destination, flags 0x49 [shble, rif, hwcn]
    ifnums:
      LISP0(43): 172.16.3.3, 172.16.4.3
    2 paths
      path 7FC0E77B4260, share 100/100, type attached nexthop, for IPv4
        nexthop 172.16.3.3 LISP0, IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
      path 7FC0E77B3E50, share 50/50, type attached nexthop, for IPv4
        nexthop 172.16.4.3 LISP0, IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
    1 output chain
      chain[0]: loadinfo 80007FC0DE66F1D0, per-session, 2 choices, flags 0003, 5 locks
                  flags [Per-session, for-rx-IPv4]
                  15 hash buckets
                    < 0 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 1 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 2 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 3 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 4 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 5 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 6 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 7 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 8 > IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    < 9 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <10 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <11 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <12 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <13 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                    <14 > IP midchain out of LISP0, addr 172.16.3.3 7FC0E31E2518
                          IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748
                  Subblocks:
                    None

R2のCEFの10.2.2.0/24のネクストホップには172.16.3.3と172.16.4.3が登録されたままです。


R2#show ip cef 10.2.2.0/24 detail
10.2.2.0/24, epoch 2, flags [subtree context, check lisp eligibility, default route]
  SC owned,sourced: LISP remote EID - locator status bits 0x00000003
  LISP remote EID: 4 packets 456 bytes fwd action encap, cfg as EID space
  LISP source path list
    nexthop 172.16.3.3 LISP0
    nexthop 172.16.4.3 LISP0
  2 IPL sources [active source]
    Dependent covered prefix type inherit, cover 0.0.0.0/0
  recursive via 0.0.0.0/0
    recursive via 172.16.2.6
      attached to GigabitEthernet2

設定内容と状態の確認(Priorityが異なるケース)

検証内容

R3のRLOCの172.16.3.3のPriorityを10から20に変更した場合の動作を確認します。

ETRであるR3の設定と状態確認

RLOCの172.16.3.3のPriorityを10から20に変更します。


router lisp
 instance-id 0
  service ipv4
   database-mapping 10.2.2.0/24 172.16.3.3 priority 20 weight 50
   database-mapping 10.2.2.0/24 172.16.4.3 priority 10 weight 50
   exit-service-ipv4
  !
  exit-instance-id
 !
 exit-router-lisp

R3のMapping Database内の172.16.3.3のPriorityが10から20に変化したことが確認できます。


R3#show ip lisp database
LISP ETR IPv4 Mapping Database for EID-table default (IID 0), LSBs: 0x3
Entries total 1, no-route 0, inactive 0

10.2.2.0/24
  Uptime: 20:15:17, Last-change: 00:00:23
  Domain-ID: unset
  Locator     Pri/Wgt  Source     State
  172.16.3.3   20/50   cfg-addr   site-self, reachable
  172.16.4.3   10/50   cfg-addr   site-self, reachable

MR/MSであるR1の状態確認

R3がR1に登録した172.16.3.3のPriorityが10から20に変化したことが確認できます。


R1#show lisp site detail
LISP Site Registration Information

Site name: Site_1
Allowed configured locators: any
Allowed EID-prefixes:

  EID-prefix: 10.1.1.0/24
    First registered:     20:16:07
    Last registered:      20:16:02
    Routing table tag:    0
    Origin:               Configuration
    Merge active:         No
    Proxy reply:          No
    Skip Publication:     No
    Force Withdraw:       No
    TTL:                  1d00h
    State:                complete
    Registration errors:
      Authentication failures:   0
      Allowed locators mismatch: 0
    ETR 172.16.2.2:28538, last registered 20:16:02, no proxy-reply, map-notify
                          TTL 1d00h, no merge, hash-function sha1, nonce 0xE0C350C9-0x90A7389C
                          state complete, no security-capability
                          xTR-ID 0xF180E005-0x7DEB7B41-0x6FFC3231-0xCD92F0F5
                          site-ID unspecified
                          Domain-ID unspecified
                          Multihoming-ID unspecified
                          sourced by reliable transport
      Locator     Local  State      Pri/Wgt  Scope
      172.16.2.2  yes    up           1/50   IPv4 none

  EID-prefix: 10.2.2.0/24
    First registered:     20:15:40
    Last registered:      00:00:47
    Routing table tag:    0
    Origin:               Configuration
    Merge active:         No
    Proxy reply:          No
    Skip Publication:     No
    Force Withdraw:       No
    TTL:                  1d00h
    State:                complete
    Registration errors:
      Authentication failures:   0
      Allowed locators mismatch: 0
    ETR 172.16.4.3:39547, last registered 00:00:47, no proxy-reply, map-notify
                          TTL 1d00h, no merge, hash-function sha1, nonce 0x9B83FB8F-0x889A67B2
                          state complete, no security-capability
                          xTR-ID 0xF3560DA6-0x58A122AE-0x156B8B9A-0xD124C412
                          site-ID unspecified
                          Domain-ID unspecified
                          Multihoming-ID unspecified
                          sourced by reliable transport
      Locator     Local  State      Pri/Wgt  Scope
      172.16.3.3  yes    up          20/50   IPv4 none
      172.16.4.3  yes    up          10/50   IPv4 none

ITRであるR2の状態確認

R2がR3から学習した172.16.3.3のPriorityが10から20に変化したことが確認できます。


R2#show ip lisp map-cache
LISP IPv4 Mapping Cache for EID-table default (IID 0), 2 entries

0.0.0.0/0, uptime: 00:00:03, expires: 00:00:56, via static-send-map-request
  Negative cache entry, action: send-map-request
10.2.2.0/24, uptime: 00:00:59, expires: 23:59:21, via map-reply, complete
  Locator     Uptime    State  Pri/Wgt     Encap-IID
  172.16.3.3  00:00:59  up      20/50        -
  172.16.4.3  00:00:59  up      10/50        -

10.2.2.0/24の転送先としてPriorityの小さい172.16.4.3のみ登録されていることが確認できます。


R2#show ip lisp forwarding eid remote detail
Prefix                 Fwd action  Locator status bits   encap_iid
0.0.0.0/0              signal      0x00000000            N/A
  packets/bytes       1/114
  path list 7FC0E77217C0, 3 locks, per-destination, flags 0x49 [shble, rif, hwcn]
    ifnums:
      LISP0(43)
    1 path
      path 7FC0E77B4260, share 1/1, type attached prefix, for IPv4
        attached to LISP0, glean for LISP0
    1 output chain
      chain[0]: glean for LISP0
10.2.2.0/24            encap       0x00000003            N/A
  packets/bytes       4/456
  path list 7FC0E7721328, 3 locks, per-destination, flags 0x49 [shble, rif, hwcn]
    ifnums:
      LISP0(43): 172.16.4.3
    1 path
      path 7FC0E77B3FF0, share 50/50, type attached nexthop, for IPv4
        nexthop 172.16.4.3 LISP0, IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
    1 output chain
      chain[0]: IP midchain out of LISP0, addr 172.16.4.3 7FC0E31E15C8
                IP adj out of GigabitEthernet2, addr 172.16.2.6 7FC0E31E2748

R2のCEFの10.2.2.0/24のネクストホップにはPriorityの小さい172.16.4.3のみ登録されていることが確認できます。


R2#show ip cef 10.2.2.0/24 detail
10.2.2.0/24, epoch 2, flags [subtree context, check lisp eligibility, default route]
  SC owned,sourced: LISP remote EID - locator status bits 0x00000003
  LISP remote EID: 4 packets 456 bytes fwd action encap, cfg as EID space
  LISP source path list
    nexthop 172.16.4.3 LISP0
  2 IPL sources [active source]
    Dependent covered prefix type inherit, cover 0.0.0.0/0
  recursive via 0.0.0.0/0
    recursive via 172.16.2.6
      attached to GigabitEthernet2